Helianthus sp.
Associate.—Pseudomops septentrionalis, Texas (Hebard, 1917).
Scorzonera acanthoclada Franch.
Associate.—Phyllodromica tartara nigrescens, Southern Uzbekistan (Bei-Bienko, 1950): On the flowers.
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).