28 



THE LOCUST SAW FLY. 

 Pteronous trilineatus Norton. 

 Order Hymenoptera; Family Tentherinidae. ■ 



In some portions of the United States this saw fly does considerable 

 damage, but no serious results from its attacks have been recorded 

 from Ohio. 



The white, irregularly semi-ellipsoidal eggs are laid in a crescent- 

 shaped slit on the under side of the leaf and generally away from the 

 mid-rib. The larva hatches in a few days and immediately begins to 

 feed upon the leaf from the under side, eating a hole in it. When the 

 , hole becomes large enough the larva works within the opening, and con- 

 tinues feeding until the leaf is destroyed. A single larva will consume 

 several leaves before it reaches maturity. 



The larva when full grown measures about two-fifths of an inch in 

 length, green in color, has twenty legs and a brownish head. When 

 mature, it drops to the ground and spins a tough, oval, dark-brown 

 cpcoon. In this it^ remains several days before transforming to 

 the pupa state. The adult emerges, in about three weeks. It has a gen- 

 eral dirty yellow color, with black markings on the head and segments 

 of the thorax and abdomen. The wings expand a trifle over half an inch.. 



In the vicinity of Washington, D. C, there are two or possibly three 

 broods in a season. In Ohio there is probably but one, although a second 

 brood may appear in the southern portion. 



It is not known whether the winter is passed in the pupa or adult 

 stage. In some breeding experiments, carried on by Prof. Comstock, 

 part of them issued in the fall and part remained in the pupa state 

 until spring. 



remedies. 



As the larvae of this insect are leaf feeders and very voracious eaters, 

 it follows that an arsenical poison should be effective against them, but 

 here, as in all other cases where poisons are applied, to be most effective 

 they must be put on while the worms are very small. 



BIBLIOGRAPHY. 



-'ISGT, Norton, Trans. Am. Ent. Soc, 1:215. 

 1879, Norton, Rept. U. S. Commr. Agri., pp. 222-224. 

 1884, Forbes, 14th Rept. 111. State Ent., p. 116. 

 1890, Packard, 5th Rept. U. S. Ent. Comm., p. 369. 

 1893, Bruner, Ann. Rept. Neb. State Hort. Soc, pp. 213-214. 



' Original description. 



