FAMILIAL ASSOCIATIONS
The females of many species of cockroaches insure varying degrees of protection to the developing young in their ways of disposing of the oötheca after it has been formed. The extent of this association between the mother and her developing progeny varies from the minimum amount of time spent by oviparous females in concealing their oöthecae, to the duration of embryogenesis in the so-called viviparous species, a period of over a month or more.
Haber (1920a) observed a female of Periplaneta americana chew a groove in a piece of pasteboard into which she attempted to deposit her oötheca. The oötheca failed to adhere to the shallow hole and fell to the floor. After several futile attempts to replace the oötheca in the hole, the female finally left the egg case on the floor of the cage and coated it with an oral secretion to which she attached bits of trash. During this operation she chased other females away when they ventured near the site. Qadri (1938) described the behavior of the female of Blatta orientalis in concealing her oötheca in a hole that she dug in sand; she deposited the egg case in the hole, coated it with saliva and sand, and then refilled the pit. Rau (1943) described in detail how females of P. americana and B. orientalis covered their oöthecae with wood dust or sand in holes they had prepared in the substrate. Both species placed a sticky oral secretion in the holes and then deposited their oöthecae therein. After coating the oöthecae with more sticky secretion, the females adjusted the oöthecae so that the keels were uppermost and then carefully concealed the oöthecae with the excavated debris. Both females spent over an hour in the act. Rau (1924) previously reported that of 90 oöthecae deposited by B. orientalis in jars containing earth and trash, 36 were placed in crevices or excavated holes, and 38 were hidden by being covered with dirt stuck to them with saliva; only 16 were left uncovered.
Edmunds (1957) described oviposition by Periplaneta brunnea. Some females spent from 30 to 40 minutes secreting from the mouth a frothy substance that was smeared on the substrate; the egg capsule was deposited in the secretion and covered with additional froth, which hardened into a very strong cement. Some females spent as long as two hours coating the capsule after it was deposited. It was not stated whether the oötheca was otherwise concealed. The female remained with her body over the oötheca for several hours and drove away other cockroaches which approached.
Sonan (1924) observed that Periplaneta americana and Periplaneta australasiae spent from 40 minutes to an hour covering their oöthecae, and that if the females were frightened away from this activity, they returned again to complete it. As well as excavating holes in the substrate in which to deposit its oöthecae, P. americana also avails itself of readymade crevices of appropriate size (Ehrlich, 1943). Species of Epilampra in Malaya were said by Annandale (1900) to deposit their oöthecae in crevices in floating logs just above the water line. However, Shelford (1906) stated that four genera (including Epilampra) of the subfamily Epilamprinae are "viviparous," in which event the females would carry their oöthecae within their bodies during embryogenesis and would not place the oöthecae in crevices in logs.
The female of Cryptocercus punctulatus was observed to make a groove in a piece of wood, then carry her oötheca 6 inches from where she had dropped it and place it in the groove; she covered the oötheca so that only a portion was visible (Cleveland in Cleveland et al., 1934). Dr. W. L. Nutting (personal communication, 1954) collected a number of oöthecae of C. punctulatus in the field and found each one almost completely sealed off with bits of wood in a deep groove in the roof of a chamber in a log. The keel of the oötheca was visible but the rest was well camouflaged. He stated that "The adult pair usually frequents the chamber at this time, while their broods of previous years occupy neighboring galleries."
Berland (1924) observed a female of Loboptera decipiens filling a hole (the abandoned nest of a hymenopteron) with earth that she carried in her mouth; he later found her oötheca behind the earthen barricade which she had erected.
In summary, the following species of oviparous cockroaches have been observed concealing their oöthecae (only those references not previously cited are given): Blatta orientalis; Cryptocercus punctulatus; Ectobius sylvester (Harz, 1956, 1957); Epilampra sp.; Eurycotis floridana (Roth and Willis, 1954a); Loboptera decipiens; Balta scripta, Methana curvigera, Methana marginalis, and Methana caneae (Pope, 1953a); Pelmatosilpha marginalis, Pelmatosilpha purpurascens, and Nauclidas nigra (Bunting, 1956); Periplaneta americana (Haber, 1919; Adair, 1923; Seín, 1923; Nigam, 1933; Gould and Deay, 1938; Rau, 1940a); Periplaneta australasiae (Girault, 1915b; Spencer, 1943; Pope, 1953); Periplaneta brunnea (Roth and Willis, unpublished data, 1958); Periplaneta fuliginosa (Gould and Deay, 1940); Periplaneta ignota (Pope, 1953); Supella supellectilium (Flock, 1941). Undoubtedly other oviparous species that drop their oöthecae long before the eggs hatch also make some attempt to conceal the oöthecae by placing them in crevices or covering them with debris.
Sometimes the oöthecae are deposited but not concealed. Hafez and Afifi (1956) reported that in Egypt Supella supellectilium attaches its oötheca to a suitable substrate with a gummy oral secretion but leaves the egg capsule otherwise exposed. We (1954) have noticed similar behavior in laboratory colonies of this species and of Blatta orientalis, as have Gould and Deay (1940). Cornelius (1853) stated that the female of B. orientalis takes care of the safety of her offspring to the extent of usually dropping her oöthecae in places which are dry and raised above the ground, although rarely one also may find some oöthecae scattered on the ground. For lack of suitable material females of Periplaneta americana sometimes did not conceal their oöthecae (Nigam, 1933). Frequently in laboratory colonies P. americana merely drops the oöthecae loosely in sand or food "in contrast to P. australasiae, which almost always went to considerable trouble to fasten their eggs securely and to conceal them with debris" (Pope, 1953). If conditions under which Nauclidas nigra is kept are not suitable, the female will drop her oötheca anywhere (Bunting, 1956). Rau (1940) stated that the female of Parcoblatta pensylvanica does not conceal her oötheca. However, Gould and Deay (1940) stated that this species deposits its oöthecae loosely behind bark. Ellipsidion affine and Ellipsidion australe attach their oöthecae to bark or the underside of leaves but apparently make no attempt to conceal them (Pope, 1953a).
The females of most of the above species have no further familial association with their offspring. The eggs hatch with no attention from the mother who is probably not even in the vicinity at that time. The young apparently do not react to the presence of the parent, as such, after hatching. This is not unexpected, as several additional oöthecae may have been deposited by these oviparous females before the eggs of the first oöthecae hatch. However, a different behavior is encountered among species that do not form a second oötheca until after the eggs of the first have hatched (see below) and in the so-called colonial species.
Shaw (1925) reported that in Australia both Panesthia australis and Panesthia laevicollis appear to live in families, and that one usually finds a pair of adults associated with from 12 to 20 nymphs in different stages of development; he continued, "it is only where the molts are very abundant that one loses sight of this familial habit." Tillyard (1926) also stated that the Australian species of Panesthia live in burrows in soil in strict family communities of a pair of adults and 10 to 20 nymphs. A related colonial species, Cryptocercus punctulatus, lives in both sound and rotten logs in colonies consisting of a pair of adults and 15 or 20 nymphs, probably representing two or three broods (Cleveland et al., 1934; Cleveland, 1948). Chopard (1938) has cited this association as an example of gregariousness, which it may well be; however, the presence of only one pair of adults in each colony suggests a more intimate relationship.
Among species of Blattella and certain other genera with similar reproductive habits the female carries her oötheca clasped in her genital cavity with the posterior portion projecting behind her. Each normal oötheca is carried for approximately the duration of embryogenesis and is not dropped until, or shortly before, hatching. We have seen (1954, fig. 65) newly hatched nymphs of Blattella vaga crawl over the body of the mother who stood quietly near the dropped oötheca; this female raised her wings and some of the nymphs crawled under them onto the dorsal surface of her abdomen. The nymphs seemed to feed on the grease covering the mother's body. The association was short-lived, however, and soon the nymphs scattered. Pettit (1940) stated that when hatching of Blattella germanica occurs in the open (on a table top), the nymphs may remain near the capsule only a few minutes. Ledoux (1945) found that newly hatched nymphs of B. germanica remained together without shelter in a single, sparse group. If the nymphs were separated by blowing on them, the group quickly reassembled, usually in the same spot. Ledoux showed that this gregarious grouping of first-instar nymphs was not necessarily a familial association by placing nymphs from two oöthecae together. In groups of 8 to 12 nymphs there was a perfect intermingling of the offspring from the two different females.
It is among the so-called viviparous cockroaches that the greatest number of observations have been made of postparturient associations between female cockroaches and their offspring. The females of these species carry their oöthecae in brood sacs within their bodies until embryogenesis has been completed. This behavior ensures protection of the young from desiccation and attack by parasites (Roth and Willis, 1955a). (See Roth and Willis, 1958a, for an analysis of oviparity and viviparity in the Blattaria.) Shelford (1906, 1916) reported that he had captured a female of Pseudophoraspis nebulosa in Borneo with numerous young nymphs clinging to the undersurface of her abdomen. He also recalled that there was in the Hope Museum (Oxford) a female of Phlebonotus pallens to which the following label was attached: "'Ceylon ... carries its young beneath its wing covers. 1878.'" Pruthi (1933) found in South India another female of P. pallens which was carrying over a dozen young nymphs on her back beneath her wings. In his paper Pruthi reproduced a photograph of this specimen with the light-colored nymphs in place on the back of the female. Hanitsch (1933) reported having seen a museum specimen from Luzon, Philippine Islands, of the apterous female of Perisphaerus glomeriformis with nymphs still clinging to her undersurface; he also reported having seen a museum specimen of a female of Ellipsidion variegatum from Australia with four young clinging to the upper side of the apex of her tegmina and six to the oötheca which projected beyond her body. Presumably this specimen was giving birth when captured. Gurney (1954; personal communication, 1958) stated that specimens of Perisphaerus sp. from Mindanao and Luzon have been found with young nymphs clinging to the middle and hind coxae. The first-instar nymph has an elongate face and specialized galeae. Karny (1925) also observed that at the slightest alarm the young of some species of Phoraspidinae creep under the dome-shaped front wings of the mother.
The newly hatched young of Leucophaea maderae have also been seen congregated under the mother on several occasions. Seín (1923) stated that after being born, the nymphs of this species gather under the mother and accompany her at night in her excursions in search of food. Pessôa and Corrêa (1928) reported that "During the first days the free larvae hide under the adult cockroach which becomes restless and active in contrast to its usual slow gait." Wolcott (1950) stated that "They are not only gregarious, but the mother broods over her young, and together they sally forth at night in search for food, until they are of such a size as to mingle with their elders."
The African mountain cockroach Aptera fusca has been observed during late summer and early winter in familial groups beneath loose bark, under stones, and in dead leaves (Skaife, 1954): "Each party consists of a number of black young ones, together with one, two or more adult females and perhaps a winged male or two. Later on they scatter and live more or less solitary lives." In Malaya Karny (1924) often found phoraspidine females between leaves surrounded by about 20 young nymphs. He stated that one also often found females of Perisphaerus armadillo surrounded by pale, yellowish-white young; similarly he had observed that Archiblatta hoevenii was found mostly in colonies made up of mothers and their young. The duration of these associations is not known.
Saupe (1928) noticed that the newly hatched nymphs of Blaberus craniifer (see footnote [12], p. [322]) collected together under the body of their mother and stated that this is as pronounced a case of brood care as Zacher had observed with Pycnoscelus surinamensis. Nutting (1953) stated that "A degree of maternal solicitude is exhibited by this roach [B. craniifer], for many times I have observed the female to remain motionless for an hour or more with her unpigmented brood clustered around and beneath her body." We, too, have observed similar behavior in laboratory colonies of B. craniifer and Leucophaea maderae.
Chopard (1950) noted that after hatching the young of Gromphadorhina laevigata remained grouped around the female for some time; the mother stood motionless, high on her legs, with her thorax curved up to make room for the brood which hid under her body. We (unpublished data, 1958) have seen young nymphs of Gromphadorhina portentosa also stay near their mother for some time after birth; the mother at this time produced a characteristic hissing sound when she was only slightly disturbed by the movement of our hand near her and her brood. The sound is produced as air is expelled through the second abdominal spiracle. We have seen recently hatched nymphs of Nauphoeta cinerea crawl beneath the mother, even under her wings, where they remained about an hour (Willis et al., 1958). Bunting (1956) observed a female of Blaberus discoidalis collect a mound of debris into which she inserted the tip of her abdomen; he found young in the mound later the same day. This female showed no maternal care for the young after birth. Whole families of cockroaches may be found in bromeliads in Brazil (Ohaus, 1900). Hebard (1920) observed a colony of adults and young of Dendroblatta sobrina on a tree trunk in the Panama Canal Zone.
Whether any of the above associations exemplify maternal care for the newly hatched young is questionable. The behavior of the mother, beyond placing her eggs in a suitable location, seems to be entirely passive. The first-instar nymphs are the active partners in these associations, and they may merely be seeking shelter under the nearest convenient object rather than under the mother as such. More extensive studies of some of these relationships will be needed before claims for maternal care, as suggested by Scott (1929), can be substantiated.