HEMIPTEROUS INSECTS ON ORANGE. 159 



fills, the larva of the parasite, a little, white, footless grub, lies concealed, 

 curled up, with its head touching its tail. In a few days it becomes a 

 pupa, and six or seven days later it emerges tiirough a large hole eaten 

 in the dry shell of the Aphis, as a slender, black, wasp-like liy, with 

 yellow legs. This fly is, of course, very minute, beiug j^^ inch in length. 

 It is Trioxys testaceipes Cresson.* (Plate XIII, Fig. 4.) 



Its work can always be seen where the Orange Aphis has been colo- 

 nized for a week or more, in the numerous bloated remains of the Aphis, 

 some of which may still contain the parasite, and others exhibit the 

 round hole through which it has made its exit. (Plate XII f. Fig. 3, c 

 and (L) 



Although only a single fly is bred from each individual of the plant- 

 louse, the numbers of the parasite increase more rapidly than those of 

 its victim, and as every Aphis is in time parasitized, no colony long es- 

 capes extermination. Were it not for the facility with which new colo- 

 nies can be started at a distance, through the flight of the winged females, 

 this species of Aphis and some others which are similarly attacked 

 would suffer complete extinction in a single season. t 



Other enemies. — Numerous other enemies combine to thin the numbers 

 of Plant-lice. Those which have fallen under observation as destroying 

 the Orange Aphis are discussed in the chapter on Predatory Insects. 

 Among the number are three species of two-winged flies {Diptera), 

 whose larvae subsist exclusively upon Plant-lice, and several species of 

 Lady birds (Coccinelliclcv) which, both as larvae and as perfect beetles, 

 rely to a very great extent upon this source for their food supply. 



Remedies for Aphis. — Moderatelj' strong applications of whale-oil soap, 

 or the kerosene washes recommended for Scale-insect, are perfectly 

 efl'ective in killing the Orange Aphis, and will not injure the young 

 growth upon which they are found. 



THE GKEEN SOLDIER- BUG. 



(Raphigaster hilar is. Fitch.) 



[Fig. 74.] 



A large green Plant-bug is sometimes observed to suck tender shoots 

 of Orange, causing them to wither and die. The same insect is, to a 

 certain extent, ])redaceous, and has been reported as sucking Cotton 

 "Worms and other insects, for which reason it has usually been classed 

 among beneficial insects. The full-grown bug is bright green in color, 

 with a very tine yellowish line around the entire margin of the insect, 

 and a black dot at the outer angles of each abdominal joint. The form 



* Described in Report of the Commissioner of Agricnlture for 1879, p. 208. 



tMr. Aslimead has described another minute, black parasite, wliich ho bred from 

 the Orange Aphis, and to which he gives the name Stenomtsius (?) aphidicola. (Orange 

 Insects, p. 67.) Three of the flies issued from the body of a single Aphis, and it may 

 be a secondary parasite, preying upon the Trioxys. 



