The Biotic Associations of Cockroaches

by Louis M. Roth; Edwin R. Willis

PREDATORS AND PARASITES OF COCKROACH EGGS

Wasps from at least six families of Hymenoptera have been recorded as developing on cockroach eggs. All the Evaniidae are presumed to be parasitic in the egg capsules of cockroaches (Clausen, 1940; Townes, 1951), although hosts for many of the described species have yet to be discovered. The presence of evaniids in dwellings indicates the presence of cockroaches (Gross, 1950). At times these wasps may become a nuisance; a family in Worthington, Ohio, complained of the evaniid wasps that they found on the windows and in other areas of their home, but they were apparently not annoyed by the oriental cockroaches in the basement (Edmunds, 1953).

The known parasites of cockroach eggs are listed below with summaries of their biology.

Family EVANIIDAE

Acanthinevania princeps (Westwood)

Synonymy.—Evania princeps [Dr. H. Townes, personal communication, 1956].

Natural host.—Cockroach eggs, Australia (Froggatt, 1906).

Brachygaster minutus (Olivier)

Synonymy.—Evania minuta Olivier [Kieffer, 1920].

Natural hosts.—Blattella germanica, Europe? (Schletterer, 1889; Kiefer, 1912; Crosskey, 1951).

Ectobius lapponicus, Europe? (Schletterer, 1889; Kieffer, 1912; Crosskey, 1951).

Ectobius panzeri var. nigripes? Great Britain (Blair, 1952): This is a presumptive record. The wasp was collected at Niton and Headon Hill, Isle of Wight, an area in which this variety of E. panzeri was the only species of cockroach known to occur.

Ectobius sp., England (Cameron, 1955, 1957): Natural History Museum records.

Adult wasps have been collected on Asparagus officinalis Linnaeus (Schmiedeknecht in Schletterer, 1889; Crosskey, 1951). Thompson's (1951) citation of records of B. minutus and Evania appendigaster from Blatta orientalis and Blattella germanica, and Cameron's (1957) citation of these records and one from Ectobius lapponicus, all attributed to Kadocsa (1921), are almost certainly in error. Kadocsa (1921, p. [33]) listed these wasps as egg parasites of cockroaches but not necessarily in Hungary and did not name specific cockroach hosts.

The present writers have found no information, other than host reports, on the biology of Brachygaster minutus. The records of this wasp parasitizing B. germanica may trace back to Schletterer, but his listing may not have been an original observation. Since the female of B. germanica carries its oötheca attached to the abdomen until or just before the eggs hatch, it would seem that the female of B. minutus (if the host records are valid) must oviposit into the oötheca of this species while it is still being carried by the female; this would not necessarily be true for the other hosts which drop the egg case long before the eggs hatch.

Distribution.—Europe: Sweden, Russia, England, France, Germany, Austria, Hungary, Switzerland, Italy (Kieffer, 1920).

Evania appendigaster (Linnaeus)

Synonymy.—Evania desjardinsii Bordage, Evania laevigata Latreille [Dalla Torre, 1901-1902].

Natural hosts.—Blatta, "exotic species" (Westwood, 1854, 1954a).

Blatta orientalis, Europe? (Schletterer, 1886; Howard, 1888, Kieffer, 1912); Egypt? (Alfieri, 1914; Adair, 1923). [Girault (1907, 1914) erroneously attributed another record to Marlatt (1902);[6] . See also notes under Brachygaster minutus with respect to Kadocsa.]

Blattella germanica? (Girault 1907, 1914). [This record is obviously an error. Girault attributed the record to Marlatt (1902); see footnote 6.]

Cutilia soror, Hawaii (Swezey, 1929; Zimmerman, 1948).

Leucophaea maderae (Schletterer, 1889; Bordage, 1896; Kieffer, 1912): These records are probably erroneous inasmuch as this cockroach incubates its eggs internally (Roth and Willis, 1954). Later, after finding that L. maderae is ovoviviparous, Bordage (1913) admitted having misidentified a parasitized oötheca from some other species; he concluded that the developing eggs of this species are protected against egg parasites because they are carried within the female. Clausen (1940), in classifying the placement of parasitic wasp eggs in relation to the host, erected the category: Egg placed in the embryo while the latter is still within the parent. He stated that although this behavior was not definitely known to occur, it probably could occur. However, the records cited above do not indicate that the alleged parasitization followed this pattern.

Neostylopyga rhombifolia, Hawaii (Swezey, 1929).

Periplaneta americana, Europe (Schletterer, 1889; Bordage, 1896; Kieffer, 1912); Réunion Island (Bordage, 1913); Puerto Rico (Seín, 1923); Jamaica (Gowdey, 1925); Hawaii (Swezey, 1929); Palestine (Bodenheimer, 1930); U.S.A., Florida (Ashmead, 1900); Maryland (Piquett and Fales, 1952); Saudi Arabia, Jedda (Cameron, 1957); Canton Island and Samoa (Dumbleton, 1957).

Periplaneta americana or P. australasiae, Formosa (Sonan, 1924).

Periplaneta australasiae, U.S.A., Florida (Ashmead, 1900); Hawaii (Swezey, 1929; Zimmerman, 1948). [Girault (1914) erroneously attributed another record to Marlatt (1902); see footnote 6, above.]

Experimental host.—Blatta orientalis, U.S.A. (Haber, 1920).

Relatively little detailed information was known about this wasp (fig. 5), one of the earliest parasites of cockroach eggs to be discovered, until Cameron (1957) studied its biology. Arnold (Kirby and Spence, 1826) discovered that the genus Evania parasitized Blatta, but did not know whether the wasp developed on the cockroach eggs or in the nymphs. MacLeay (Westwood, 1843) determined that Evania developed within the oöthecae of cockroaches. Westwood (1854a) found the larvae, pupae, and adults of E. appendigaster in egg cases of an unidentified species of cockroach found on orchids received from Calcutta.

Adult behavior.—Adult wasps visited flowers of parsley, Petroselium crispum, and fennel, Foeniculum vulgare (Margretti in Schletterer, 1886; Crosskey, 1951). In Hawaii the adult wasps have been seen resting on leaves coated with honey dew (Williams et al., 1931); Evania sp. were attracted to the honey dew secreted by a diaspine scale insect (Williams, 1931). Adults lived two to three weeks in captivity with ample food and water (Cameron, 1957).

Oviposition.—Shelford (1912, 1916) erroneously supposed that Evania, by means of her cleaverlike abdomen, opened the oötheca at the crista and then deposited her egg or eggs on the eggs of the cockroach. Haber (1920) observed and described oviposition. The female wasp crawled over the surface of the oötheca, actively vibrating her antennae, and settled with the axis of her body parallel to the axis of the egg case as it lay upon its right side. Lying on her right side, the wasp extended her ovipositor and punctured the oötheca in the fifth cell on the left side; she remained in this position for about 15 minutes. Cameron (1957) described similar oviposition behavior that lasted about half an hour. Kieffer (1912) and Crosskey (1951) stated that the female deposits her eggs before the walls of the oötheca harden.

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Fig. 5.—Evania appendigaster. Left, dorsal view, X 8. Right, side view, X 5. (Reproduced with permission. British Museum [Natural History], 1951, figs. 1A and 1B).

Development.—Kieffer (1912) stated that the larvae in this family eat the cockroach eggs and pupate in the oötheca without forming a cocoon. Smith (1945) stated that the larva feeds on one cockroach egg after another until all are destroyed; by that time it is full grown and it pupates within the oötheca. Cameron (1957) found that there are five larval instars and that in material from Saudi Arabia there are three or possibly four generations a year.

Distribution.—Tropical and subtropical parts of the world as far north as New York City, and all of Europe except the northern part (Kieffer, 1920; Townes, 1949). The wide distribution of Evania has been attributed to the abundance of host cockroaches on ships between the Tropics (Haldeman, 1847). Kieffer (1903) appears to have shown some correlation between the numbers of species of cockroaches found in various geographical regions and the numbers of species of evaniids found in similar regions. However, the number of blattids he listed is small.

Evania dimidiata Fabricius

Synonymy.—Evania abyssinica Westwood [Schletterer, 1889].

Natural host.—Blatta orientalis, Egypt? (Alfieri, 1914).

Evania subspinosa Kieffer

Natural host.—Periplaneta sp., Fiji (Lever, 1946): Although Lever (1946) listed this species as a cockroach-egg parasite, he did not state that he actually reared it from Periplaneta oöthecae.

Hyptia dorsalis of Ashmead

Synonymy.—Dr. H. Townes, (personal communication, 1956) believes that this wasp was probably either H. reticulata, H. harpyoides, or H. thoracica; it is not possible to tell which without reexamining Ashmead's specimens; these apparently have been lost.

Natural host.—Parcoblatta pensylvanica, U.S.A., Mississippi (Ashmead, 1900).

Hyptia harpyoides Bradley

Natural hosts.—Parcoblatta virginica, U.S.A., Ohio (Edmunds, 1952a, 1953a, 1954).

Parcoblatta pensylvanica, U.S.A. (Muesebeck, 1958).

Parcoblatta uhleriana, U.S.A., Natick, Mass.: Oötheca collected by L. Roth, May 17, 1956; wasp emerged June 12, 1956 (pl. [33], B); determined by Dr. H. Townes. The keel region of the oötheca of P. uhleriana (pl. [18], B) is different from that of any other species of Parcoblatta (Hebard, 1917; Lawson, 1954) so there can be no doubt as to the species of cockroach parasitized by this wasp.

Development.—The last instar larva overwinters inside the cockroach oötheca (Edmunds, 1954). Five oöthecae yielded one parasite each (Edmunds, 1953a).

Distribution.—Canada, Ontario. U.S.A.: New Hampshire and Minnesota to South Carolina, Mississippi, Texas, and Kansas. Upper and Lower Austral Zones (Townes, 1951).

Hyptia reticulata Say

Natural host.—Parcoblatta pensylvanica, U.S.A., Missouri (Rau, 1940).

Adult wasps have been taken on parsnip, Pastinaca sativa (Robertson, 1928).

Distribution.—U.S.A.: Pennsylvania to Florida and Louisiana. Mexico. Upper Austral to Tropical Zones (Townes, 1951).

Hyptia thoracica (Blanchard)

Natural host.—Parcoblatta pensylvanica, U.S.A., Ohio (Edmunds, 1952a, 1953a, 1954).

Adult behavior.—Copulation was rapid, lasting only a few seconds. Blooms of Asmorrhiza longistylis were placed in a cage with adult wasps. The insects were attracted to and fed on the flowers (Edmunds, 1954).

Development.—Entire contents of oötheca are eaten by the single larva. Last instar larva overwinters inside the oötheca. Emergence in Ohio was around the middle of June. The emergence hole made by this genus was about 2 mm. in diameter. The hole was made at the top side of the oötheca near one end. Adult took about 65 minutes to emerge from the time its mandibles first broke through the oöthecal wall. (Edmunds, 1954.)

Distribution.—Canada, Ontario, U.S.A.: Connecticut to Wisconsin, south to Florida and Texas. Upper Austral to Tropical Zones. (Townes, 1951.)

Hyptia sp.

Natural host.—Cariblatta delicatula, Cuba (Hebard, 1916a); Parasite identified by Ashmead.

Hyptia sp. (undescribed)

Natural host.—Parcoblatta sp., U.S.A., Ohio (Edmunds, 1952a).

Prosevania punctata (Brullé)

Synonymy.—Evania punctata Brullé [Townes, 1949].

Natural and experimental hosts.—Blatta orientalis, Istrian Peninsula (Fahringer, 1922); Algeria (Cros, 1942); U.S.A., Ohio (Edmunds, 1954).

Blattella germanica? Europe? (Girault 1907, 1914); Europe (Fahringer, 1922). [The records on this host are extremely doubtful. Girault erroneously cited Marlatt (1902) as the source of this record; see footnote 6, page 236. Fahringer, however, claimed that he obtained seven female parasites from oöthecae of Blattella germanica. He placed female parasites with adults of B. germanica in a glass cage. As soon as oöthecae could be seen between folds of a woolen rag, he removed all the larger cockroaches and held the oöthecae until the parasites emerged. Fahringer may have been dealing with a different species of cockroach, because placing oöthecae in crevices (or between folds of rag) is a habit foreign to B. germanica, the female of which usually carries her oötheca until hatching or until about a day before. Edmunds (1953b) could not induce this wasp to parasitize eggs of B. germanica.]

Periplaneta americana, Istrian Peninsula (Fahringer, 1922); Palestine (Bodenheimer, 1930); U.S.A., Ohio (Edmunds, 1952, 1953b, 1954).

Adult behavior.—The wasps (pl. [33], A) are very active; they walk about a great deal and fly short distances. They are often found in abundance in buildings infested with the larger domiciliary cockroaches where they may reproduce for many generations without leaving the premises. Specimens have also been collected outdoors. (Edmunds, 1953, 1954.) As the adult walks about, the laterally compressed abdomen moves up and down like a waving flag; because of this behavior, these insects are commonly known as ensign-flies. Cros (1942) maintained adults 17 days without food. Edmunds (1954) fed adults on unidentified flowers in the laboratory. He also maintained them for 20 days after capture on a 5-percent honey solution.

Oviposition.—A female P. punctata selected oöthecae of P. americana for oviposition and ignored those of B. orientalis and Parcoblatta pensylvanica in the same cage. Oviposition was accomplished as described for Evania appendigaster. One oötheca was turned over onto its right side by the wasp before she oviposited. (Edmunds, 1952.) Although there seemed to be a "preferred" position for oviposition, it was not obligatory. The usual position was for the female to face the keel of the oötheca, but she also oviposited from the opposite side or, rarely, directly down into the side of the oötheca. The average time spent by females in 10 ovipositions was 29 minutes (range 16-62 minutes). The wasp apparently could not determine whether the eggs had been previously parasitized. The wasp laid her egg between the cockroach eggs rather than in them and she oviposited into oöthecae that had just been dropped and those two weeks old or older. On three occasions nymphal cockroaches emerged within a few hours after the wasp had oviposited. (Edmunds, 1954.) Apparently, for successful parasitization the wasp must oviposit before the cockroaches have reached the final stages of preemergence development. Edmunds (1954) placed females of Periplaneta americana that were carrying oöthecae, into cages with Prosevania; some of the female wasps showed considerable interest in the attached oöthecae, but he observed oviposition only into egg cases that had been dropped by the cockroaches.

Cros (1942) described an interesting reaction that he called "instinctive hostility" of the oriental cockroach toward Prosevania. A wasp was placed in a jar in which a cockroach had just deposited its oötheca. The wasp tried to oviposit into the egg case but was upset and pursued by the cockroach. The cockroach placed herself over the oötheca, standing high on her legs, and remained there motionless. The wasp then approached from the rear, slipped under the cockroach, and, unnoticed by the cockroach, climbed on the oötheca and oviposited successfully.

Development.—In Blatta orientalis: The developmental period was completed in 40-57 days in summer and fall (Cros, 1942). Time from oviposition to emergence of adult varied from 45-177 days; three parthenotes from an oviposition by an unfertilized female wasp developed in 45-53 days (Edmunds, 1954). In Blattella germanica: Almost 4 weeks spent in development (Fahringer, 1922). In Periplaneta americana: Three wasps developed in 127 days (Edmunds, 1952). Only one parasite develops in each oötheca. There were three generations a year in Ohio. (Edmunds, 1954.) In Algeria there were two to three generations per year. The adult emerged from the oötheca through a hole 4 mm. in diameter. (Cros, 1942.) Parthenogenesis exists; the unfertilized eggs produced only males (Edmunds, 1954).

Distribution.—Eastern U.S.A., from New York and Ohio south to Georgia (Townes, 1949). Europe, Syria, Palestine (Kieffer, 1920).

Szepligetella sericea (Cameron)

Synonymy.—Evania sericea Cameron [Townes, 1949, personal communication, 1956]. Evania impressa Schletterer [Townes, p. c., 1956].

Natural hosts.—Cutilia soror and Neostylopyga rhombifolia, Hawaii (Swezey, 1929).

Periplaneta americana and Periplaneta australasiae, Hawaii (Swezey, 1929; Zimmerman, 1948).

Periplaneta sp., Fiji (Lever, 1943, 1946).

Adults are sometimes found resting on leaves covered with honey dew (Williams et al., 1931).

Zeuxevania splendidula Costa

Natural hosts.—Loboptera decipiens, France (Lavagne, 1914; Genieys, 1924).

Picard (1913) believed that Z. splendidula parasitized L. decipiens and not its eggs; however, Lavagne (1914) explained the true relationship by dissecting two specimens of Z. splendidula from oöthecae of L. decipiens.

The following information is taken from Genieys (1924): Oviposition.—Wasp egg is introduced into the still-soft oötheca before the wall hardens. Some oöthecae had four oviposition scars but never contained more than two parasite eggs. Development.—Larva commences development in July or August. Only one larva completes development, but it eats all the eggs in the oötheca. The wasp passes the winter as a last instar larva and pupates in the spring; the adult emerges during the spring or in June. Hyperparasitism.—About 10 percent of the oöthecae of Loboptera decipiens that were parasitized by Z. splendidula were also hyperparasitized by an eulophid (see Syntomosphyrum ischnopterae, p. [249]).

Family CLEONYMIDAE

Agamerion metallica Girault

Natural hosts.—Ellipsidion australe, Australia, Queensland (Dodd, 1917): "the parasite when ready to emerge fully occupies the whole space of the destroyed eggs."

Cockroach, Australia, New South Wales (Dr. B. D. Girault, 1915a).

Family ENCYRTIDAE

Blatticida pulchra Ashmead

Natural host.—Cockroach eggs on orange leaves, Australia, New South Wales (Gahan and Peck, 1946). According to Dr. A. B. Gurney the oötheca associated with the type specimens of the wasps in the United States National Museum is possibly Balta sp. (Burks, personal communication, 1956).

Blatticidella ashmeadi (Girault)

Synonymy.—Blatticida ashmeadi. Blatticida Girault, 1915, is preoccupied by Blatticida Ashmead, 1904. In 1923 Gahan and Fagan renamed Blatticida Girault, Blatticidella. [Burks, p. c., 1956.]

Natural host.—Cockroach, Australia, Queensland (Girault, 1915).

Cheiloneurus viridiscutum (Girault)

Synonymy.—Cristatithorax Girault = Cheiloneurus Westwood [Mercet, 1921].

Natural host.—Ellipsidion australe, Australia, Queensland (Dodd, 1917).

Comperia merceti (Compere)

Synonymy.—Comperia merceti var. falsicornis Gomes [Peck, 1951].

Natural hosts.—Blattella germanica, Brazil, Distrito Federal (Gomes, 1941): In the English summary of his paper, Gomes states that C. merceti var. falsicornis was reared from B. germanica. However, in the body of the paper, he states that the supposed origin of the parasite was the oötheca of B. germanica. Burks (personal communication, 1956) does not believe that this wasp parasitizes the eggs of B. germanica. We (unpublished data, 1957) exposed six oöthecae of B. germanica to C. merceti. In order to retard water loss the oöthecae were removed from the females by cutting the insects in two so that each oötheca remained attached to the posterior part of the abdomen. No wasps developed in these oöthecae.

Supella supellectilium, U.S.A., Kansas (Lawson, 1954a); Hawaii (Zimmerman, 1944; Compere, 1946; Keck, 1951).

Adult behavior.—Males and nonovipositing females showed a flea-like jumping tendency. Adults were attracted to light and were found near windows. Both sexes pursued an erratic course in walking and continually touched the surface with their antennae. (Lawson, 1954a.)

Oviposition.—The wasp (pl. [34], B) selected a site on an oötheca with the sheath of her ovipositor; it was uncertain whether there was a definite preference for oviposition sites. Wasp tended to choose a nearly horizontal position for oviposition. She preferred to oviposit into eggs about 2 weeks old, although she would place eggs in oöthecae less than a week old and in embryos in the green band stage. There were 1-50 oviposition punctures per oötheca. (Lawson, 1954a.)

Development.—If enough wasp larvae were present, they ate all eggs in an oötheca. Occasionally wasps developed in one end of an oötheca while cockroaches developed in the other; when this occurred, the cockroach nymphs always emerged last. The developmental period was 30-41 days at room temperature. There were 5-25 parasites per oötheca. The single exit hole in the oötheca varied from 0.6 to 0.9 mm. in diameter. (Lawson, 1954a.)

Distribution.—U.S.A.: New Jersey south to Florida, west to Illinois, Kansas, and Arizona. West Indies; Central and South America; Hawaii. (Burks, personal communication, 1956.)

Dicarnosis alfierii Mercet

Natural hosts.—"Phyllodromia" sp., Egypt (Mercet, 1930): According to Mercet, Dr. Alfieri claimed that this wasp parasitized one of the species of "Phyllodromia" found in Egypt, namely, Phyllodromia [= Blattella] germanica, Phyllodromia [= Supella] supellectilium and/or Phyllodromia treitliana. We do not know to which modern genus the host of this wasp belonged.

Cockroach, Egypt? (Mercet in Compere, 1938.)

Eutrichosomella blattophaga Girault

Natural host.—Cockroach, Australia, Queensland (Girault, 1915).

Family EUPELMIDAE[7]

Anastatus blattidifurax Girault

Natural host.—Cockroach, Australia, Queensland (Girault, 1915).

Anastatus floridanus Roth and Willis

Natural host.—Eurycotis floridana, U.S.A., Florida (Roth and Willis, 1954a).

Experimental hosts.—Blatta orientalis, Eurycotis floridana, and Periplaneta americana, U.S.A. (Roth and Willis, 1954a).

Adult behavior.—Female wasps are sexually receptive almost immediately on leaving the oötheca. Mating takes 3-4 seconds. Males mate repeatedly and may fertilize several females; females may also mate more than once. At about 80° F. the female wasps lived 2-4 days, males one day.

Oviposition.—The female wasp first probes the oötheca with her sheathed ovipositor until she finds an acceptable spot; she then drills through the wall of the oötheca with her ovipositor. One female oviposited for 5 hours, but briefer periods were more usual. We have seen six or more females ovipositing simultaneously into an oötheca of Eurycotis floridana. One female was seen to feed on material that oozed from the oviposition puncture. The wasp (pl. [34], A) may oviposit into the oötheca of E. floridana while it is still being carried by the female, as well as in oöthecae that have been dropped and which have hard walls. Eggs 36 days old were successfully parasitized.

Development.—In Eurycotis floridana: In the laboratory, development was completed in 34-36 days at about 85° F. This time was regulated to some extent by the number of parasites in the oötheca.

There is evidence that larvae eat unhatched wasp eggs or other larvae. In 34 oöthecae exposed to many female wasps, the maximum number of parasites to emerge was 306; yet an average of 601 wasp larvae were dissected from four oöthecae that had each been exposed to 50 female wasps one week earlier. The larvae usually eat all the host eggs. Cockroach eggs that were not eaten by the wasp larvae sometimes developed but usually failed to hatch. Adult wasps made one to six emergence holes in the oötheca; the average number in 42 oöthecae was two holes.

Number of parasites per oötheca.—In Blatta orientalis: One of 111 oöthecae exposed to female wasps yielded 48 parasites. In Eurycotis floridana: One oötheca parasitized in the field yielded 68 parasites; 8 oöthecae exposed to single wasps for their entire lifespan yielded an average of 50 ± 6 parasites (range 23-81); 34 oöthecae exposed to many wasps for their entire lifespan yielded an average of 198 ± 8 parasites (range 93-306). In Periplaneta americana: Nine oöthecae of 152 exposed to the wasps were found to be parasitized when dissected; 11 adults emerged from one oötheca; no parasites emerged from the other 8 oöthecae.

Sex ratio.—4 ♀♀:1 ♂ from ovipositions by isolated females. In the one oötheca collected in the field, the ratio was 21.6 ♀♀:1 ♂. Parthenogenesis exists; the unfertilized eggs produced only males.

Anastatus tenuipes Bolívar y Pieltain

Synonymy.—Anastatus blattidarum Ferrière. Dr. C. Ferrière (personal communication, 1957) is of the opinion that his A. blattidarum is a synonym of A. tenuipes. He stated "I have never been able to see the unique type of A. tenuipes B. y P., which is in Madrid, but the description agrees with A. blattidarum. I had not yet knowledge of Bolívar's description, when describing my species. The parasite of cockroaches eggs [Supella supellectilium] should be called A. tenuipes Bol." Mani (1938) synonymized Solindenia blattiphagus Mani with Anastatus blattidarum.

Natural hosts.—Supella supellectilium, Anglo-Egyptian Sudan (Ferrière, 1930, 1935); U.S.A., Arizona (Flock, 1941); Egypt (Alfieri, in Hafez and Afifi, 1956). Ohio (Hull and Davidson, 1958).

Periplaneta americana, India (Burks in Roth and Willis, 1954a).

Cockroach, Hawaii (Weber, 1951); India (Mani, 1936).

The following is based on parasites that developed on eggs of Supella supellectilium (Flock, 1941): Adult behavior.—Wasp may be seen running rapidly on walls in buildings infested with the cockroach host. The wasp rarely flies but hops proficiently; when disturbed it can hop from several inches to several feet. The female licks up the drop of fluid that oozes from the oviposition puncture. Females die in a few days, but if fed honey and water may live two weeks. Oviposition.—The female selects an oötheca by feeling with her antennae. Flock stated, without citing experimental evidence, that the age of the egg case was apparently the chief factor determining choice. The wasp took 15-45 minutes to oviposit. Three females oviposited simultaneously into a single oötheca; a single female repeatedly oviposited into one oötheca at intervals. Development.—Completed in an average of 32.6 days at a constant temperature of 82° F.

Number of parasites per oötheca.—Average about 10.7 (range 4-16) (Flock, 1941); 15 (Ferrière, 1935).

Sex ratio.—4 ♀♀:1 ♂ (Ferrière, 1935); average of 6 ♀♀:1 ♂ (Flock, 1941). Parthenogenesis occurs; the unfertilized eggs produced only males (Flock, 1941).

Distribution.—U.S.A.: Maryland, south to Florida, west to Illinois, Kansas, and Arizona. Guatemala; Hawaii; India; Egypt; Sudan. (Burks, personal communication, 1956).

Eupelmus atriflagellum Girault

Natural host.—Blattella germanica, Australia, Queensland (Girault, 1924).

Eupelmus sp.

Natural host.—"Tree cockroach," U.S.A., Florida (Howard, 1892).

Solindenia picticornis Cameron

Natural hosts.—Allacta similis, Hawaii (Perkins, 1906, 1913; Timberlake, 1924; Swezey, 1929; Zimmerman, 1948).

Other species of cockroaches, Hawaii (Perkins, 1913).

Family PTEROMALIDAE

Pteromalus sp.?

Natural host.—Leucophaea maderae?, Jamaica (Westwood, 1839; Sells, 1842). [This host is undoubtedly an error. Sells stated that the oötheca which contained 96 unidentified chalcids had 16 dentations at the edge; the description fits the oötheca of an oviparous cockroach and not that of L. maderae (see Roth and Willis, 1954). Westwood (1839, footnote p. [423]) stated that at the meeting of the Entomological Society in 1838 Mr. Sells exhibited 94 specimens of a small Pteromalus (apparently identified by Westwood) obtained from one cockroach oötheca. This same record of Sells was published posthumously in 1842, although in this paper he identified the host oötheca as "Blaberus" maderae. Cameron (1955) lists a European record of Pteromalus sp. from Periplaneta americana citing Girault (1914) as the source of the record. Girault's record was apparently taken from Westwood's footnote mentioned above.]

Systellogaster ovivora Gahan

Natural hosts.—Blatta orientalis, U.S.A., Illinois (Gahan, 1917).

Parcoblatta pensylvanica, Canada, Ontario (Judd, 1955).

Parcoblatta sp., U.S.A., Ohio (Edmunds, 1952a, 1953a).

"Blattid," U.S.A., Maryland (Gahan, 1917).

One oötheca of P. pensylvanica yielded 14 parasites with a sex ratio of 2.5 ♀♀: 1♂ (Judd, 1955). The average number of parasites in 11 oöthecae of Parcoblatta sp. collected in 1950-51 was 27 wasps (Edmunds, 1952a, 1953a). The adults made two to three emergence holes in the oötheca (Edmunds, 1953a; Judd, 1955).

Family EULOPHIDAE

Melittobia chalybii Ashmead

Natural host.—Periplaneta americana, U.S.A., Missouri (Rau, 1940a): M. chalybii is normally a parasite of Coleoptera and Hymenoptera (Peck, 1951). This is the only record from cockroach eggs. Burks (personal communication, 1956) stated that this species will attack any insect to which it is exposed and can be a serious pest in insect cultures of practically any insect order. In nature it seems to prefer the nests of aculeate Hymenoptera; Rau suggested that the parasites were probably brought into his laboratory with mud nests of Sceliphron caementarium (Drury).

Mestocharomyia oophaga Dodd

Natural host.—Ellipsidion australe, Australia, Queensland (Dodd, 1917).

Syntomosphyrum blattae Burks

Natural hosts.—Parcoblatta sp., U.S.A., Ohio (Burks, 1952; Edmunds, 1952a, 1953a): Ten oöthecae yielded an average of 92 wasps (Edmunds, 1952a). Five oöthecae, collected a year later, yielded an average of 74 wasps; adults sometimes made two to three exit holes in the oötheca (Edmunds, 1953a).

Cockroach, U.S.A., West Virginia (Burks, 1952).

Syntomosphyrum ischnopterae (Girault)

Synonymy.—Epomphaloides ischnopterae Girault [Peck, 1951].

Parker and Thompson (1928) called their hyperparasite Tetrastichus sp. However, Dr. B. D. Burks (personal communication, 1955) has examined the teneral specimens which Parker and Thompson deposited in the U.S. National Museum; he stated that the species is apparently Syntomosphyrum ischnopterae. In view of the experimental work by Parker and Thompson (see below), this wasp may prove to be a hyperparasite on evaniids in cockroach oöthecae rather than a primary parasite on cockroach eggs. (See Zeuxevania splendidula, p. [243].)

Natural hosts.—Ischnoptera sp. [probably Parcoblatta sp. (Rehn, personal communication, 1958)]. U.S.A., Maryland (Girault, 1917).

Zeuxevania splendidula Costa (an evaniid in the oöthecae of Loboptera decipiens), France (Parker, 1924; Parker and Thompson, 1928).

The following information is from Parker and Thompson (1928): Adult behavior.—Courtship and mating were accomplished as soon as adults emerged, and in a manner similar to that in other chalcids. The females oviposited only into oöthecae that were parasitized by Zeuxevania, never into normal, nonparasitized oöthecae. Oviposition.—Oviposition occurred two days after mating. The female wasp stroked the oötheca with her antennae, selected a site, and bored into the oötheca with her ovipositor. She inserted the ovipositor deeply and oviposited for 10-30 minutes. The eggs were deposited randomly on the evaniid larva, some upright and others lying down. Development.—Eggs of the hyperparasite hatched within 3 days and the larvae commenced feeding on the host larva. There were 30 and 50 hyper-parasites in two oöthecae. Sex ratio.—5 ♀♀:1 ♂ (from 3 oöthecae).

Distribution.—U.S.A., District of Columbia, Maryland (Burks, 1952).

Tetrastichus australasiae Gahan

Natural host.—Periplaneta australasiae, Sumatra (Gahan, 1923).

Tetrastichus hagenowii (Ratzeburg)

Synonymy.—Entedon hagenowii Ratzeburg, Blattotetrastichus hagenowii (Ratzeburg) [Burks, 1943]. Tetrastichodes asthenogmus Waterston. G. J. Kerrich (personal communication, 1957) compared the type of Tetrastichodes asthenogmus Waterston with authentically determined material of Tetrastichus hagenowii and concluded that T. asthenogmus is only a weakly developed specimen of T. hagenowii. He stated, "The longitudinal dorsal grooves of the scutellum, which are strongly developed in normal hagenowii, are only rather faintly developed in Waterston's type and also the second specimen, which was dissected and mounted on a series of ten microscope slides. No doubt it was this faint development that caused Waterston to describe the species in Tetrastichodes, a segregate that has since been recognized by Dr. Burks (Proc. U. S. Nat. Mus., 1943) as being not truly generically distinct from Tetrastichus."

Natural hosts.—Blatta orientalis, Seychelles (Ratzeburg, 1852); India (Usman, 1949).

Blatta sp., U.S.A., Louisiana (Gahan, 1914).

Blattella germanica (Burks, 1943; Peck, 1951). [In personal communications, Burks and Peck cite Howard (1892) and Marlatt (1902, and the 1908 revision of 1902) as sources for this host record. However, B. germanica is not mentioned specifically as a host of T. hagenowii in the sources cited nor in the 1915 revision of Marlatt's 1902 paper cited by Burks (1943); see footnote 6, p. [236].]

Neostylopyga rhombifolia, Hawaii (Pemberton, 1941): This record is based on one parasitized oötheca. We have exposed, at three different times, groups of 10 to 20 oöthecae of N. rhombifolia to many newly emerged T. hagenowii, but none of the eggs was parasitized (Roth and Willis, unpublished data, 1957).

Parcoblatta sp., U.S.A., Ohio (Edmunds, 1953a).

Periplaneta americana, Africa (Crawford, 1910; Nash, 1955): Nash's record was incorrectly attributed to Syntomosphyrum glossinae Wtstn., a parasite of tse-tse fly pupae (Jordan, 1956), Formosa (Takahashi, 1924; Sonan, 1924); Palestine (Bodenheimer, 1930); Puerto Rico (Seín, 1923; Plank, 1947, 1950; Wolcott, 1951); St. Croix, Virgin Islands (Beatty, 1944); Hawaii (Schmidt, 1937); U.S.A.: Missouri (Rau, 1940a); Ohio (Edmunds, 1955); Florida (parasitized oöthecae were collected near Orlando by members of the Orlando Laboratory, Entomology Research Branch, U.S. Department of Agriculture; the parasites were identified by Burks, personal communication, 1955). Fiji (Lever, 1943); India (Mani, 1936; Usman, 1949); Trinidad and Saudi Arabia (Cameron, 1955). Westwood (1839) stated that 70 parasites belonging to the genus Eulophus emerged from an oötheca of P. americana collected on shipboard. Burks (personal communication, 1955) stated that the wasp was probably T. hagenowii.

Periplaneta australasiae, Australia (Shaw, 1925); India (Usman, 1949); Saudi Arabia, Trinidad (Cameron, 1955); Formosa (Sonan, 1924).

Periplaneta brunnea, U.S.A., Florida (parasitized oöthecae were collected near Orlando, by members of the Orlando Laboratory, Entomology Research Branch, U.S. Department of Agriculture. The parasites were identified by Burks, p. c., 1955).

Cockroach eggs, Formosa (Maki, 1937); Ceylon (Waterston, 1914): Taken on an oötheca.

"Domestic cockroaches," U.S.A., Louisiana (Girault, 1917).

"Roach egg cases," Panama Canal Zone (Rau, 1933).

Evania sp., Hawaii (Ashmead, 1901; Perkins, 1913); Guam (Fullaway, 1912); Fiji (Lever, 1946); Europe, Cuba, Florida (Marlatt, 1902, 1915).

Experimental hosts.—Blatta orientalis, Eurycotis floridana, and Periplaneta americana, U.S.A. (Roth and Willis, 1954b): We have maintained T. hagenowii for over two years through more than 30 generations on eggs of both B. orientalis and P. americana.

Periplaneta fuliginosa, U.S.A., Pennsylvania (Roth and Willis, 1954b); Massachusetts (Roth and Willis, unpublished data, 1957).

Schmidt (1937) deduced that T. hagenowii was a primary parasite of eggs of P. americana because the parasitized oötheca was obtained from a cage covered with screen too fine to permit entry of a larger parasite, such as an evaniid. As noted above, we have reared T. hagenowii for more than 30 generations on cockroach eggs, none of which was ever exposed to parasitization by an evaniid. If T. hagenowii were ever hyperparasitic on Evania, this relationship would be accidental, the eulophid happening to oviposit into an oötheca already containing an evaniid, or vice versa.

Adult behavior.—The male mates soon after becoming adult; he mounts the female from behind, grasps her antennae with his own antennae, and vibrates his wings during copulation. Mating is accomplished in from "several" to 20 seconds (Takahashi, 1924; Edmunds, 1955). The adults are positively phototactic and are capable of hopping for some distance (Edmunds, 1955). The females feed on material that oozes through the oviposition puncture (Roth and Willis, 1954b). Females lived 10 days (Seín, 1923). Without food, females lived 7.8 days and males 3.4 days, but when fed dilute honey females lived 12.5 days (Usman, 1949). Females lived 5-11 days (Roth and Willis, 1954b). Fed water and sugar, the wasps lived 2-6 weeks at 65°F. (Cameron, 1955). Without food, 9 females lived an average of 3.5 days and 9 males an average of 1.7 days, but when fed on raisins, 9 females lived an average of 25 days and 9 males 15 days (Edmunds, 1955). In Formosa there were six generations from April to December (Maki, 1937).

In Hawaii, Severin and Severin (1915) caught 571 T. hagenowii in 10 kerosene traps that were set up to sample populations of Mediterranean fruitfly. Apparently the parasite is attracted by the odor of kerosene.

Oviposition.—The female wasp explores the surface of the oötheca with vibrating antennae (Edmunds, 1955). She bends her abdomen ventrad and repeatedly touches the surface of the oötheca with her valvae; when she finds an acceptable oviposition site, the wasp unsheathes her ovipositor and bores through the wall of the oötheca (Roth and Willis, 1954b). The wasp deposited her eggs in 2-5 minutes (Edmunds, 1955). Wasps oviposited (pl. [34], C) into young or old eggs of P. americana (Roth and Willis, 1954b). A single wasp parasitized more than one oötheca and more than one wasp oviposited into the same oötheca (Roth and Willis, 1954b; Edmunds, 1955). We found freshly laid wasp eggs in 34 empty but previously parasitized oöthecae from which the wasps had emerged (Roth and Willis, 1954b).

Development.—In Periplaneta americana: Development is completed in an average of 36 days (range 29-58 days) (Maki, 1937); 29-40 days (Lever, 1943); average of 23.6 days (range 22-26 days) at 62°-85° F. (Usman, 1949); about 3 months at 60°-65° F. (Cameron, 1955); 31-60 days at 70°-80° F. (Edmunds, 1955). We found that the wasps completed development in 23-56 days at about 85° F., but the period depended on the number of wasps in the oötheca; the larger the number of wasps (up to an average of about 70 wasps per oötheca), the shorter the time required to complete development. Wasps in oöthecae containing 70 or more parasites developed in an average of about 32 days (Roth and Willis, 1954b). Wasp larvae eat the contents of the cockroach egg in which they start development, then rupture the chorion and attack adjoining eggs (Cameron, 1955; Edmunds, 1955). All eggs are consumed when the parasite density is high, but if too few larvae develop per oötheca, some cockroach eggs survive and the embryos complete development (Roth and Willis, 1954b). However, a certain number of cockroach nymphs must complete development to enable the survivors to force open the crista and emerge from the oötheca; fewer than this number of surviving nymphs will be trapped and killed as effectively as if they had been eaten by the parasite. The adult parasites emerge from one to three holes cut through the wall of the oötheca (Usman, 1949; Roth and Willis, 1954b).

Number of offspring per female.—In Blatta orientalis: In the laboratory, 5 oöthecae were left with each of 25 female wasps for their entire lifespans; of the 125 oöthecae, 32 were parasitized. The average number of offspring per female was 66 (range 5-164) (Roth and Willis, 1954b). In Periplaneta americana: Each of 206 oöthecae was exposed to a single female wasp for 24 hours; the average number of offspring per female was 103 (range 50-139). Five oöthecae were left with each of 38 females for their entire lifespans; of the 190 oöthecae, 81 were parasitized. The average number of offspring per female was 94 (range 45-168 [from original data]) (Roth and Willis, 1954b).

Number of parasites per oötheca.—In Eurycotis floridana: In the laboratory, 3 oöthecae that had been exposed to 20 female wasps yielded an average of 648 parasites (range 606 [from original data] to 685) (Roth and Willis, 1954b). In Neostylopyga rhombifolia: One oötheca yielded 73 parasites (Pemberton, 1941). In Parcoblatta sp.: Two oöthecae yielded an average of 100 parasites (Edmunds, 1953a). In Periplaneta americana: 100 parasites per oötheca (Seín, 1923); 140 (Schmidt, 1937); 25 (Rau, 1940a); 7-38, average 33 (Usman, 1949); 71 (Wolcott, 1951); 4 oöthecae exposed to 20 female wasps yielded an average of 204 wasps (range 164 [from original data] to 261) (Roth and Willis, 1954b); average of 30-40 (Cameron, 1955); 39 oöthecae yielded an average of 93 parasites (range 12-187) (Edmunds, 1955). In Periplaneta australasiae: Oöthecae yielded an average of 40-50 adult parasites (Cameron, 1955); about 50 (Shaw, 1925).

Sex ratio.—3 ♀♀:1 ♂ (Usman, 1949); 4 ♀♀:1 ♂ (Cameron, 1955); 2-8 ♀♀:1 ♂ (Roth and Willis, 1954b); 1.2 ♀♀:1 ♂ (Edmunds, 1955). Parthenogenesis exists; the unfertilized eggs produced only males (Roth and Willis, 1954b; Edmunds, 1955).

Distribution.—Probably worldwide. Eastern and southern U.S.A.; Central and South America; Europe; Arabia; Africa; India; Formosa; Hawaii.

Tetrastichus periplanetae Crawford

Natural hosts.—Periplaneta americana, Mozambique (Crawford, 1910); Union of South Africa (parasites reared from oöthecae collected in Durban, Natal, by the City Health Department): The parasites were identified by Burks (personal communication, 1956). Jamaica (Gowdey, 1925); Réunion Island (Bordage, 1913).

"Domestic cockroach," Puerto Rico (Wolcott, 1951).

Tetrastichus sp. I

Taxonomy.—Burks (personal communication, 1956) stated that this species (specimens of which are in the U.S. National Museum) is very close to T. hagenowii.

Natural hosts.—Periplaneta americana, Union of South Africa (parasites reared from oöthecae collected in Durban, Natal, by the City Health Department [Burks, p. c., 1956]).

Periplaneta australasiae, Manila, Philippine Islands (Burks, p. c., 1956).

Tetrastichus sp. II

Synonymy.—Because of the war, Cros (1942) could not determine this insect specifically. He designated it provisionally and with reserve under the name Eulophus sp. However, Burks (p. c., 1956) stated that the species is most certainly a Tetrastichus from the description given; but, it is apparently not T. hagenowii because of its brilliant steel-blue color.

Natural host.—Blatta orientalis, Algeria (Cros, 1942): Adult behavior.—Mating began as soon as wasps emerged from an oötheca. Males mated repeatedly. Adults lived up to 5 days in summer and up to 12 days in fall. There were up to four generations per year in the laboratory. Oviposition.—Wasps oviposited into oöthecae 6, 22, 40, and 43 days old, and the parasites developed successfully. More than one female oviposited into the same oötheca. Oviposition was of long duration. Development.—From egg to eclosion took an average of 34 days in summer (range: 30-38 days, 5 oöthecae), and an average of 67 days in fall (range: 58-73 days, 3 oöthecae). An average of 55 parasites developed per oötheca (range 21-105, 5 oöthecae); over 130 wasps emerged from a sixth oötheca. Sex ratio.—10-20 ♀♀:1 ♂.