THE HYMENOPTERA 



341 



intermediate larval instars the green color of the body is modified by the 

 presence of many black spots. After feeding from 2 to 3 weeks the larvae 

 crawl down to the ground and pupate, the cocoons resembling those al- 

 ready described. Adults from these pupse appear in late June or July 

 and lay eggs for a second generation, and in some cases a few of the 

 insects have a third generation before winter. The second and third 

 generations (when present) do not attract much attention generally, as 

 interest in the currants in most cases ceases for the season with the 

 gathering of the crop. 



Control. — Spray the currants as soon as the leaves have developed 

 or as soon as the "worms" appear, with arsenate of lead, standard 

 formula or a little weaker. If treatment is necessary after the fruit 

 has begun to turn red, dust fresh hellebore over the plants, using 1 lb. of 

 hellebore thoroughly mixed with about 5 lb. of air-slaked lime or flour. 

 The great difficulty in controlling 

 these pests is that the adults ap- 

 pear and lay their eggs during a 

 rather long period and it is often 

 necessary to spray for those larvae 

 which appear early, before all the 

 leaves are fully developed. Ac- 

 cordingly, those leaves which come 

 out after the spray has been applied 

 are not protected and larvae ap- 

 pearing afterwards can feed on 

 them without being poisoned, and 

 a second spray is often needed on 

 this account. 



Fig. 356. — Pear Slug {Caiiroa cerasi L.) : 

 a, adult; b, larva with slime removed; c, 

 larva from above, coveredby its slime; d, 

 leaf showing work of the insect and with 

 larvae present: a, b and c much enlarged; 

 d, somewhat reduced. {From Berlese, 



modified from U. S. D. A. Div. Ent. 



Circ. 26.) 



The Pear Slug {laliroa cerasi .L). 

 — This insect feedson the leaves 

 of the pear, plum and cherry, and 

 though a native of Europe is now 

 found almost everywhere in this 

 country (Fig. 356). 



The adult is a saw-fly about a fifth of an inch long, with a black body. It 

 appears after the leaves develop in spring and lays its eggs in slits sawed in the 

 leaves, forming a sort of blister at each place. The larvse soon produce a dark- 

 brown glossy shme which covers them and conceals their true outline, making 

 them somewhat similar to soft snails in appearance. They feed on the leaf tissue, 

 skeletonizing it, and molt four times. After the fourth molt the slime disappears 

 and the larva is orange-yellow and does not feed. It now passes to the ground in 

 which it pupates. A second generation follows, but a few of the pupse remain 

 unchanged in the ground until the following spring. In the South there are three 

 generations, at least in some cases. 



