THE FALL WEB-WORM. 



In the earth of the jar were found 28 pupae of Tachina flies, leaving 

 7G caterpillars and 3 pupae killed by fungus, or 63 per cent. 



In both experiments it has been assumed that each Tachina fly had 

 killed one caterpillar. 



On Xovember 15, 188G, the jars were again investigated, and it was 

 found that a number of the pupae had been killed by the fungus since 

 October 18, 1886, and that in fact all the remaining ones did not look 

 healthy. The percentage of death by the fungus in the two experi- 

 ments was thus increased to G3 per cent, in Experiment I and to G7 

 per cent, in Experiment II. 



TRUE PAIiASITES OF THE WEB-WORM. 



Up to the present time no parasites of this insect have ever been re- 

 corded. On August 18, 18S3, we bred a number of egg-parasites from 

 a batch of eggs found upon a willow leaf at Washington, but unfortu- 

 nately no description was made of them at the time, and, as they be- 

 longed to the soft-bodied genus Trichogramma, the specimens have 

 now become so much shriveled and altered that they are unfit for de- 

 scriptive purposes. We noticed after our return from Europe in Sep- 

 tember of this year that, at a number of points in New England, the 

 worms were quite commonly attacked by parasites, and careful inves- 

 tigation at Washington by Mr. Lugger showed the presence of no less 

 than five distinct species of primary parasites in addition to the Trick- 

 ogramma just mentioned. These will be considered in some detail. 

 The first was a new egg-parasite which we have named Telenomus hi- 

 fidus ; the others were all parasitic on the larva 1 , and consisted of a 

 Bracouid (Meteorus hyphantrice n. sp.): a Microgaster (Apanteles hyphan- 

 triee, n. sp.); an Ophionid (Limncria pallipes Prow), and a Taehinid, 

 which, though probably new, we shall not attempt to describe. These 

 last four have been mentioned in about the order of their relative abun- 

 dance and consequent importance. An astonishing number of Web- 

 worms were killed by the four parasites, and so many died from this 

 cause and from the fungus disease previously mentioned as to fully 

 warrant the prediction of almost complete immunity for the summer of 

 1887. 



In addition to these parasites found last fall, the note books of the 

 Division show a prior breeding of another primary parasite, which will 

 not be treated in detail here on account of insufficient material. I; is 

 an external feeder on the larva and belongs to the genus Euplectrus, 

 It is closely related to E. plutyhypence, described by Mr. Howard in Bul- 

 letin 5 of this Division. 



Telenomus hi fidus Riley. — A single egg of the moth ot' II. cunea is a 

 very small affair, yet it is large enough to be a world for a little para- 

 site, which undergoes all its transformations within it, and finds there 

 all the food and lodgement required for the short period o( its life. 



