364 ENTOMOLOGICAL NEWS. [Oct., 'l/ 



Notes on the Construction of the Cocoon of Praon 



(Hym., Braconidae). 



By C. N. AINSLIE, U. S. Dept. Agriculture, Bureau of Ento- 

 mology, Cereal and Forage Insects.* 



The parasites of various aphids have been receiving much 

 attention during recent years and their widely differing habits 

 have proved most interesting to the students of their life his- 

 tories. 



In a short sketch in Entomological Nezi's of March, 1909, 

 pp. 110-112, the writer described briefly a discovery he had 

 recently made of the process by which the bodies of aphids, 

 killed by the attack of their Aphidiine enemies, are fastened by 

 the larvae of the parasite to a firm base, thus affording the 

 larvae a reasonably secure shelter during the period of pupa- 

 tion. This discovery was made by using the exceedingly simple 

 device of inverting upon the stage of a microscope a slide on 

 which the aphid was being glued after the larva had split ven- 

 trally the abdomen of its dead host. Through the slide thus 

 placed the movements of- the larva could be readily watched 

 as it smeared the torn edges of the aphid's body-wall to the 

 glass with a generous supply of a viscous fluid. Previous to 

 ihis observation, made nearly nine years ago, no one seems to 

 have been able to solve the mystery of this attachment of the 

 dead body, although the entire operation had frequently been 

 carefully watched, from above. The process as then detailed 

 has been since confirmed by Mr. E. O. G. Kelly, of the Bureau 

 of Entomology, and by other observers as well. It appears 

 to be a well established fact that nearly all the braconid para- 

 sites of aphids fasten their former hosts to a base in much the 

 same manner. 



On the other hand the Aphelinu ^-parasitized bodies of aphids 

 are anchored without the abdominal rent. Just how this is ac- 

 complished is not yet definitely known since it can be learned 

 only by means of circumstantial evidence. It seems likely that 

 a certain amount of an adhesive fluid is in some manner forced 

 through the stomata or other pores in the body-wall and thus 



* Published with the permission of the Secretary of Agriculture. 



