176 FIRST ANNUAL REPORT OP 



five is thus destroyed. As four of these parasites are new to science, 

 and are all probably confined to this one species of insect, 1 will 

 briefly desci ibe them. 



They all belong to the order IIymenoptera, and by far the most 

 common of them is a little fly of a dark metallic green color, with 

 reddish legs, which is represented highly magnified in Plate 2, Figure 

 6, the hair line below showing the natural size. Its larvae infest the 

 caterpillar in great numbers, and cause it to swell to three and four 

 times its normal size. After they have absorbed all thejuices of their 

 victim, they form for themselves very line brownish coccens, which 

 are so crammed together that they give the puffed-up worm the rough- 

 ened appearance, shown at Plate 2, Figure 5, and prevent the skin 

 from collapsing after they have left, so that it may be found within 

 the gall at any time during the winter. These minute flies all leave 

 the gall through a single minute hole, which must be made by one of 

 their number. They are active little creatures, running nimbly, with 

 their antennae always bent towards the surface on which they travel. 

 They have a wonderful power of jumping, and are able to leap the 

 distance of afoot so suddenly and rapidly that they are, for the mo- 

 ment, scarcely visible. I have counted over 150 of them in a single 

 caterpillar, and the mother fly must gnaw for herself a passage Ihrough 

 the gall, and leisurely insert her batch of egg-! in the inmate. This 

 fly be family, and may be called the Inflating Chal- 



cis fly. The family to which it belongs has scarcely been at all studied 

 in America, and very few species have been described. I there- 

 fore leave the species, for the present, undescribed, it apparently be- 

 longing to the genus Pirene. 



parasite which infests this caterpillar, is represented in 

 the p< Mate 2, Figure 9, the hair line above showing the 



natural size. It is a black fly, and its larva, which is often found at 

 the bottom of the gall during the month of August, is a white, foot- 

 ■:. and attenuated at the head. Some oi these 

 e and become tlies in the fall of the year, while 

 others re i maggot state till spring. The pupa is whitish, 



with :• m< r iers confined and darker. This fly belongs to the same 

 (Chalds) family as the preceding, and to the genus Eurytoma. I 

 name it, in honor of my esteemed friend, Mr. A. Bolter, of Chicago — 

 an entomologist, as enthusiastic as he is modest, and an indefatigable 

 collector. When I think of the many happy hours we have spent 

 together, and recall our many pleasant hunting grounds, the following 

 prettj lines are ever floating in my mind: 



" I long to walk by the meadow's brook, 

 To Tisit tbe fields and the woods once more, 

 To loiter long in the shady nook, 

 And tread the paths I have trwd before ; 

 Or, under the spreading branches to lie 

 And watch the clouds in the azure sky." 



Annexed will be found a full description of this parasite : 



