THE STATE ENTOMOLOGIST. 109 



about one-half inch in lengthy and in form were like those of the common 

 Blow-fly. The head was attenuated and retractile and furnished with two 

 minute curved hooks, and the last segment was squarely cut off, slightly 

 concave and with the usual two spiracles or breathing-holes wiiich this class 

 of larvae have at their tails. Their color was of a translucent 3'ellow, and 

 they looked very much like little pieces of raw fat beef. They went into 

 the ground and remained in the larva state all winter, contracted to pupse 

 in the April following, and the flies commenced to issue the last of May. 

 This fly differs only from the Army-worm Tachina-fly (^Exorista militaris, 

 Walsh, Eep. II, Fig. 17) in lacking the red tail entirely or in having 

 but the faintest trace of it, and I consider it but a variety of that species. I 

 infer that this same Tachina-fly attacks the Cecropia w^orm in widely differ- 

 ent parts of the countiy ; for I have received from Mrs. Mary Treat, of 

 New Jersey, two dipterous pupte which probably belonged to this species, 

 and which had also in the larva state infested a Cecropia worm. 



The Mary Chalcis-fly-( OAa/cfs marice, Eiley) — In May, 1869, 1 received 

 fron\ Mr. V. T. Chambers, of Covington, Ky., numerous specimens of the 



beautiful large Chalcis-fly figured here- 

 with (Fig. 39), which he had taken 

 from the cocoon of the Polyphemus 

 iioth, which is quite common, and is- 

 sues as early as the middle of Febru- 

 ary in that locality. ilesa3\s, " I was 

 satisfied that the cocoon did not con- 

 tain a living Polj'jihemus and therefore 

 opened it. It contained so little be- 

 sides these insects and their exuvias, 

 as to suggest sti-ongl}- the old idea that the caterpillar had been metamor- 

 phosed into them (as in a sense it had). There were 47 of them, of which 

 23 were females. As all the males and some of the females were dead when 

 I opened the cocoon, I think it likely that the former never do emerge, and 

 perhaps but few of the latter ; otherwise Polyphemus w^ould soon be ex- 

 terminated." 



I can very well imagine that most of these Chalcis-flies would die in 

 their efforts to escape from the tough cocoon of the Polj'phemus, but it so 

 happens that these same parasites have been found by Mrs. Mary Treat, of 

 Vineland, X. J., to prey upon the Cecropia worm, from the cocoon of ^ hich 

 they can niore easily escaj^e. The same fly also attacks the Promethea Avorm, 

 and Mrs. Treat has had a similar experience with Mr. Chambers, of finding 

 them dead in its cocoon. She has upon two occasions found cocoons with 

 a dead Chalcis-fly fast in the hole wdiich it had eaten to make its escape ; and 

 upon cutting open such cocoons they were found literally packed with dead 

 Chalcis-flies. It would seem that they all make their escape through the 

 hole made by some one of their number, and that if this particular one 

 fails in the undertaking, they all perish rather than make holes for them- 

 selves. 



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