DAMAGE TO PLANTS BY COCKROACHES
Cockroaches characteristically feed on dead plant and animal material. Damage to living plants occurs principally in the Tropics or under subtropical conditions in greenhouses in temperate regions. Among the depredations attributed to cockroaches in text books, damage to plants is seldom emphasized. This is surprising in view of the many records cited below.
Capt. William Bligh (1792), while collecting breadfruit trees in Tahiti to take to the West Indies, wrote in his log during January 1789: "This morning, I ordered all the chests to be taken on shore, and the inside of the ship to be washed with boiling water, to kill the cockroaches. We were constantly obliged to be at great pains to keep the ship clear of vermin, on account of the plants."
Westwood (1869) stated that Pycnoscelus surinamensis was very destructive in orchid houses feeding on buds and young shoots. Later Westwood (1876) exhibited the bulb of an orchid from Ecuador which contained six species of cockroaches: Blatta orientalis, [Periplaneta?] americana, [Nauphoeta?] cinerea, [Leucophaea?] maderae, and two others unknown to him. Fullaway (1938) stated that cockroaches damage root tips, buds, and flowers of orchids. Periplaneta americana has been said to eat the root tips and blossoms of orchids (Taschenberg, 1884) and to devour the open flower petals of Cattleya orchids as well as the aerial roots and flower spikes of Vanda orchids (Rau, 1940a). Wainwright (1898) stated that Periplaneta australasiae had been observed in an orchid house in Perthshire where over a period of three years it had caused a good deal of damage. Skinner (1905) reported that P. australasiae in greenhouses in Pennsylvania showed no preference for any one plant but ate both plants and flowers of orchids, roses, and carnations. Lucas (1918) received specimens of P. australasiae which had played havoc with orchids especially Cattleya and Vanda. Morse (1920) reported that both P. australasiae and Pycnoscelus surinamensis were obnoxious in a conservatory in Massachusetts where they gnawed the tips of the aerial roots of orchids. Swezey (1945) in Hawaii stated that the following cockroaches have been reported as occasional minor pests on orchids: Blatta orientalis, Blaberus discoidalis, P. americana, and P. surinamensis; he further stated that Graptoblatta notulata had been intercepted at Honolulu on orchids from India.
Watson (1907) stated that Blatta orientalis, Periplaneta americana, and Periplaneta australasiae were injurious in the tropical plant houses at Kew: "at night they come out and run or fly about among the plants, devouring flowers and leaves like rabbits. Such plants as Eucharis, Crinum and Alpinia, when in flower, have little chance in the palm house, where the cockroaches are most abundant; they also find out the ripening bananas and soon devour them." Raffill (1910) stated that in plant houses in England B. orientalis, P. americana, and P. australasiae commonly, and Nauphoeta cinerea, Nauphoeta flexivitta, and Pycnoscelus surinamensis more rarely, are extremely destructive to plants. Flowers having a strong perfume, such as orchids, Eucharis, Crinum, and Hedychium, were often attacked while other flowers nearby were left uninjured.
Plank and Winters (1949) reported that in Puerto Rico the species of Orthoptera most injurious under greenhouse conditions was Periplaneta americana. Large nymphs destroyed 25 to 30 percent of freshly planted seed of Cinchona pubescens. In Hawaii the host plants of P. americana are blossoms of Canna and Tribulus, and the host plants of Periplaneta australasiae are Pritchardia and Sida (Zimmerman, 1948). On St. Kitts, B.W.I., young cotton plants were severely attacked by P. australasiae; this caused loss of the stand on a considerable area and necessitated replanting (Ballou, 1916). P. australasiae was reported damaging the Polystichum aristatum Presl [= Lastrea aristata variegata] in a greenhouse (Thilow and Riley, 1891). Laing (1946; British Museum [Natural History], 1951) stated that P. australasiae abounds in greenhouses and forcing pits where it may do considerable damage to the plants. Periplaneta fuliginosa is also troublesome in greenhouses because of its tendency to feed on seedlings and succulent plants (Dodge and Rickett, 1943).
Ectobius lapponicus has been observed feeding in galleries in the thick skin of young aspen in 25 percent of the trees examined (Stark in Bei-Bienko, 1950). The aquatic cockroach Epilampra abdomen nigrum fed on the leaves of Jussiaea natans in an aquarium (Crowell, 1946). Ischnoptera deropeltiformis has been taken while it was feeding on a fleshy fungus (Agaricus sp.) in dense woods in Indiana (Blatchley, 1920).
Diploptera punctata, the cypress roach or beetle roach, has been found in Hawaii feeding on ripening mangoes and papayas, oranges on the tree, and the outer covering of the pods of Acacia farnesiana (Bridwell and Swezey, 1915). Pemberton (1934) stated that D. punctata "disfigures our cypress trees by eating the bark from the young branches, often giving them a dead appearance over much of their leaf area." Fullaway and Krauss (1945) added, "This injury [to cypress] is so severe that sometimes areas of leaves die and turn brown. The Japanese cedar, ironwood, citrus and algaroba (kiawe) trees are attacked in a similar manner." Similar injury to cypress was described by Hebard (1922). In addition to girdling Cupressus, D. punctata injures Cryptomeria in the same fashion and also attacks algaroba, lime, and other plants (Pemberton and Williams, 1938). Zimmerman (1948) cited the following host plants for D. punctata in Hawaii: "Cupressus macrocarpa, Casuarina, Cryptomeria, Citrus, geraniums, Acacia farnesiana pods, mango fruits, orange fruits, papaya fruits."
In the reports of damage to plants by cockroaches, Pycnoscelus surinamensis has been implicated most often. This species is undoubtedly one of the economically most important cockroaches, being the vector of the chicken eyeworm as well as feeding on plants. In addition to the few reports of damage caused by this species that have already been mentioned, P. surinamensis has been reported to be very destructive in New Orleans to palms and ferns, attacking large alsophilas avidly, eating out the hearts (Anonymous, 1893). Zappe (1918) in Connecticut reported damage in a greenhouse to roses valued, at that time, at several hundred dollars; P. surinamensis had girdled the rose bushes, done much damage to Easter lilies, and in another greenhouse had eaten the bark from the stems of poinsettias. In Germany this species bit off the tips of the aerial roots and ate the petals of orchids (Zacher, 1920). Lucas (1923) reported damage to cucumber plants in a greenhouse in Surrey. Damage by P. surinamensis to the stems of rose bushes has been reported in Rhode Island and Pennsylvania; the canes were attacked both under and above ground (Caudell, 1925). Doucette and Smith (1926) reported a heavy infestation of P. surinamensis in a range of greenhouses in Philadelphia: "The roaches were present literally by the millions.... Although the roaches had been observed in cabinets and trash barrels for several months, it was not until the manager had occasion to go through the house one evening that he discovered that roaches were the cause of the troubles previously attributed to soil condition, watering, fungus, and other agencies.... About 30,000 to 35,000 rose plants from a total of 200,000 in the three more heavily infested houses were so badly injured by the gnawing off of the bark, young buds, and shoots of the main stems, that they were not in condition to be kept in the beds for another season."
In Haiti Pycnoscelus surinamensis damaged the tubers of growing potatoes (Hoffman, 1927). Illingworth (1927, 1929) reported that in Hawaii P. surinamensis was a minor pest of pineapples, feeding on the roots. This species was very plentiful in a propagating pit in England where it did much damage to various seeds and seedlings (Lucas, 1930). Roeser (1940) summarized some of the above-mentioned damage caused by P. surinamensis and added damage to chrysanthemums in Hawaii and tobacco in Sumatra where this cockroach destroyed 300,000 plants in a few days. Roeser was of the opinion that living plants were eaten only as a substitute when the earth became poor in food material. Zimmerman (1948) listed as host plants of P. surinamensis in Hawaii: "blossoms of Tribulus; reported feeding at roots of pineapples, and unconfirmed reports of damage to underground parts of some other plants." Goodliffe (1958) reported damage by this species to banana plants in a conservatory in northern England. Cohic (1956) implied that in New Caledonia "Racines de légumes" were attacked by P. surinamensis and that Zea mays Linnaeus was attacked by Supella supellectilium. Wolcott (1924a) reported that P. surinamensis damaged transplanted tobacco plants in Puerto Rico by eating the interior of the stalks. Tobacco planters in Cuba consider P. surinamensis injurious to the roots of tobacco plants (Bruner and Scaramuzza, 1936); this belief was confirmed in the laboratory, where adults and nymphs destroyed the roots and stems of tobacco plants two inches high and ate into the edges of the leaves. Dammerman (1929) reported that in Malaya this species often appeared in large numbers in gardens where it gnawed at the underground parts of vegetables and ornamental plants. Lever (1947) listed it as a pest on the leaves of pineapple.
Blattella vaga may occasionally damage seedlings in the laboratory (Flock, 1941a), but no damage has been reported in the field (Ball et al., 1942). Heer (1864) reported receiving a shipment of cycads from Cuba with all stages of Periplaneta americana living in holes in the branches, apparently subsisting on the starchy tissues. Goldenberg (1877) stated that sago trees provide cockroaches with their favorite nourishment. Scudder (1879) found Eurycotis floridana living in the tops of the cabbage palmetto, on which he presumed it fed. Parcoblatta americana has been observed feeding on an apple 6 feet above ground (Fulton, 1930).
[X. PROTOZOA ASSOCIATED WITH COCKROACHES]
The classification of the Protozoa follows that of Kudo (1954). The use of the asterisk (*) is explained in footnote [3], page [4].
Phylum PROTOZOA
Class MASTIGOPHORA
Order EUGLENOIDINA
Family EUGLENIDAE