196 EEPORT UPON COTTON INSECTS. 



UNNAMED CHALCID PARASITE. The folio wing passages from my notes 

 concern a parasite which, owing to a press of other affairs, has not yet 

 been worked up. 



August 27. I found yesterday a cotton-worm about five-eighths of an inch in length 

 which, although yet alive, was being destroyed by three green larvae which were 



upon it. I found the specimens about 10 

 a. m. Last evening I observed that the 

 cotton-worm was nearly eaten. The para- 

 sites had very short bodies, which when 

 they moved were pointed at one end. I 

 had intended to describe the specimens 

 this morning, but I find they have spun 

 cocoons about their bodies. 



August 28. I found crawling over the 

 ground a small cotton-worm infested by 

 five parasites evidently of the same species 

 as those mentioned in my note of August 27. 



FiG.42.-UnnamedchahTid. A W U8t 29--The small green parasites 



which I found yesterday destroyed the cot- 

 ton-worm, and, excepting two specimens which I put in alcohol, began to spin cocoons 

 during the night. 



The insects bred from these specimens were small, black, chalcid flies, 

 shown at Fig. . They were nearly eight-hundredths of an inch (2 mm ) 

 in length. The general color was black, but the legs, antennae, and 

 mouth parts were honey-yellow. The head, thorax, and abdomen were 

 nearly equal in width, and the thorax was longer than the abdomen, 

 which was pediceled and subtruncate at tip. The antennae were 7- 

 jointed. 



The larvae were greenish white, oval, somewhat pointed at one end, 

 with yellow spiracles or breathing-holes, and were fleshy and footless. 

 They were sluggish in motion, moving by the alternate contraction and 

 expansion of the segments. The number of segments of the body was 

 plainly thirteen. The full-grown larvae were about 0.08 inch or 2 mm in 

 length, and were about half as wide as long. The cocoons which they 

 spun were ovoid in form, grayish white in color, and about the size of the 

 full-grown larvae. 



That these larvae spun cocoons is an interesting fact, as by far the 

 large majority of the Chalcididae transform to naked pupae within the 

 bodies of their hosts. The fact of their being found preying externally 

 upon the cotton-worms is an anomalous one. Had the worms upon which 

 they were found been more nearly full-grown, and had the effects of 

 their outside work been less apparent, their appearance might have been 

 explained on the ground that they had finished their work inside and 

 had merely issued to spin their cocoons, and were observed in the in- 

 terval between their issuing and the commencement of the spinning. 

 The cotton- worms upon which they were found, however, were less than 

 half-grown, and could not have afforded these parasites subsistence from 

 the birth of the latter upward. Moreover, the rapidity with which the 



