OF WASHINGTON, VOLUME XI, 1909 (,5 



method for removing the parasitized aphids was adopted 

 that of cutting off the inhabited portion of the plant without 

 molesting the aphid skin or enclosed parasite. 



hi order to study the development of the Lysiphlebus larva 

 after the skin of the aphid turns brown, full-grown aphids 

 containing a full-grown Lysiphlebus larva were placed on glass 

 slides with the ventral side next to the slide. For a short time 

 before death, and four to six hours after death of the para- 

 sitized aphid, the yellowish parasitic larva can be seen through 

 the thin semitransparent skin of the host; thus the revolutions 

 of the parasitic larva, while shaping the aphid body into tin; 

 globular form as observed by Professor Webster (Proceedings 

 Ent. Soc. Washington, vol. ix. p. 110), can be seen until the 

 skin begins to change its color. The aphid becomes very feeble 

 just before death, but tenaciously grasps the leaf and dies 

 thereon with a rigid death grip. This tends to hold it to the 

 leaf temporarily while the parasitic larva is shaping the host 

 body into a globular form. When the parasitic larva finishes 

 shaping and partially drying the aphid skin it pushes its head 

 through the ventral side, and, by working its body into the 

 opening, makes a slit the entire length of the abdomen, and by 

 pushing, twisting, and revolving converts it into an irregular 

 oval-shaped opening. It then begins to fasten the aphid to t he- 

 leaf or other object upon which the host insect happened to 

 make its last stand, by spinning silken threads and spitting out 

 a glutinous fluid, attaching one end of the thread to the leaf or 

 other object, and the other to the inside wall of the aphid skin. 

 The larva moves its head back and forth from leaf to aphid, 

 progressing forward with each stroke, thus forming a zigzag 

 strand of silk around and around the opening until the aphid 

 skin is made fast. The larva continues spinning and shaping a 

 cocoon on the inside wall of the aphid skin for 20 to 26 hours, 

 when the cocoon is finished. The silken film formed over the 

 ventral opening is not transparent or but faintly so in speci- 

 mens removed from plants, but it is quite transparent when 

 attached to the glass slide and by careful focusing and adjust- 

 ment of light the insect can be readily observed. 



After finishing the cocoon, the larva folds itself and becomes 

 quiet ; wing pads, legs, and antenna? become apparent in 60 to 

 75 hours from the time the larva began making its cocoon; it 

 changes color from yellow to black in 100 to 120 hours, and 

 becomes adult in 7 to 8 days (the length of these different 

 stages depends upon the temperature I. 



