130 Bulletin 76 



it would be pleasant to find that the Pimpla bad especial predilection for 



female cocoons. 



Whether in this respect or not, in others the parasite does certainly 

 exercise discrimination as to the place where she deposits her eggs. It is 

 very interesting to watch one of these Pimplas when placing her eggs in the 

 cocoons. She is so intent upon her task that one has no diflBculty in ob- 

 serving her closely. She is quite brisk even to nervousness in her move- 

 ments, flying quickly from one cocoon to another, hastily, but sharply, in- 

 specting each. If the larva inside has not finished the spinning and its last 

 molt she does not leave an egg, but flies off to the next cocoon. If the 

 cocoon is done and the chrysalis formed, she then places herself over one 

 end and strongly arching the abdomen thrusts her ovipositor into the 

 chrysalis. Then by two or three successive thrusts she works the egg deeply 

 into the unfortunate victim, withdraws the ovipositor and flies away. 

 Sometimes she will examine and leave several cocoons before she finds one 

 that she considers a fit place for an egg, but often the eggs are deposited 

 rapidly. I have seen five cocoons thus parasitized in less than as many 

 minutes. In rare instances, both moth and parasite come from the same 

 cocoon both apparently well developed. 



DISEASE OF THE LARVAE 



Forbes' writes : "The forest tent caterpillar, an outbreak of which 

 species occurred last year in southern Illinois, was again seen in the same 

 region this season, but in number so greatly reduced as to inflict little, if 

 any damage. The condition and fate of examples collected by us in south- 

 ern Illinois this year and kept in breeding cages till they perished, con- 

 firmed my supposition of a destructive contagious disease among them, 

 apparently the principal cause of their disappearance last year. This was 

 one of the diseases know as rauscardine, similar to that of the silk worm 

 occasioned by the well known fungus Bolrylis bassiana." I have seen a 

 number of caterpillars that seemed to be affected by the disease mentioned 

 above and Weed'^ apparently thinks that it has existed in New Hampshire. 

 There is also a bacterial disease which has attacked the caterpillar in several 

 states and this also is found here. Most probably it is one or both of these 

 diseases which have attracted the notice of several correspondents who 

 have written of "sick caterpillars." On some of the trees which I exam- 

 ined last season there were many diseased caterpillars. Thus we may 



I S. A, Forbes, Insects of Illinois, State Entomol. 111. Rpt. 3, p. 13, (1885), 

 1 Loc. cit. p. 93 



