[35] 



Report of the State Entomologist. 



177 



Usually Destroyed by a Parasite. 

 No effectual method is known by which to protect the grapevine 

 from these caterpillars, and resort must therefore usually be had to hand- 

 picking. But in collecting and destroying them care should be taken 

 to save from destruction those which have attached to their body a 

 large number of small oval white objects re- 

 sembling eggs (see Fig. 6) and generally 

 mistaken for them. They are not eggs but 

 the pupal-cases of the parasite — the natural fig. 6— Caterpillar of Dar- 



enemy of this caterpillar. So faithful is it APSA Myeon bearing the co- 

 . . .« , <. n j -n coons of the Microgaster 



to its mission that very tew ol the caterpillars parasite. 



escape its persistent search and reach maturity. Perhaps nine out of 

 ten are destroyed by it. The parasite is a small four-winged fly, 

 belonging to the parasitic family of Braconidce, and is probably 

 Apanteles congregatus (Say).* Having discovered one of the cater- 

 pillars, it pierces its body in numerous places, depositing an 

 egg in each wound. These in due time hatch out into grubs 

 within the caterpillar, where they feed upon its interior, 

 instinctively avoiding the consumption of the vital parts that their food 

 may continue to be suitable for them. Usually after the last molting 

 of their host, while to all outward appearance it is uninjured and 

 thriving, although careful observation may have shown it to have 

 refrained from feeding for several days, all at once a host of little 

 heads may be seen eating their way through the skin of its back 

 and sides. Within an hour's time the entire brood of grubs — a hun- 

 dred or more it may be in number, have wriggled outwardly, and 

 with their terminal segment fastened to the body by a few silken 

 threads spun for the purpose, commence building about them their 

 small firm, egg-like, snow-white cocoons, which, securely attached 

 and standing on end are usually so numerous as to cover all of the 

 upper part of the body and the sides of their victim. In two or three 

 hours, they are all inclosed.f In about a week, the grubs have com- 

 pleted their rapid transformations, when a neatly fitted lid is pushed 

 open at the top of each little cocoon, pressed to one side, and the 



* I have had the same parasite from larvae of Thyreus Abbotii, Philampelus Pandorus, 

 and Sphiiix kalmice— the last not a grapevine feeder. 



tFor an interesting account and graphic illustration of the peculiar manner in which 

 these Microgaster cocoons are spun on the body of Philampelus (and probably on D. 

 Myron also), see an article in the American Naturalist for 1878, vol. xii, pp. 558-560, by Mr. 

 J. P. Marshall. 



23 



