108 REPOHT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



the winter in both the pnpa and fly states. Prom the known prefer- 

 ence of this fly for decaying or putrescent flesh, it is probable that the 

 female is attracted more to diseased or injured chrysalides than to vig- 

 orous worms. 



Another species (Cyrtoneura stabiilans Fallen, Fig. 37), the habits of 

 which are rather predaceous than parasitic, was figured and described, 

 but not identified, in the Department Eeport on Cotton Insects. We 

 may appropriately consider it here, though it really preys upon the 

 chrysalis. Seven larvae emerged from eggs which had been deposited 

 upon the leaves surrounding Aletia pupae, and reached full growth in 

 teh days, having meantime devoured six Aletia pupae. They then en- 

 tered the ground and remained in the pui)a state five days. 



We have also obtained this fly from Aletia chrysalides, and quote 

 the following passages from the American Naturalist (September, 1882, 

 p. 746), as bearing on the ques- 

 tion whether it is a parasite 

 or a scavenger: 



Is Cyrtoneura a Parasite or 

 Scavenger? — Last spring wc sent 

 specimens of a Muscid for determi- 

 nation to Mr. E. H. Meade, Brad- 

 ford, England, and lie kindly wrote 

 •QS as follows regarding this species 

 which was bred from chrysalides of 



the Cotton Worm : 



. . , , 'Fig. Ti.— Cyrtoneura stahulans: a, ess (natural size) ; &. 



The Dipterous insects which I egg (enlarged) ; c, larva (enlarged) ; d/head and first thor- 



received yesterday are one male and a^ic segment of larva, stiU more liighly magnified ; e, 



^ „ - pupariuni ; /, adult, natural size indicated by hair lines. 



two females of Cyrtoneura stabiilans (After Comstock.) 



Fallen. This fly is common through- 

 out Europe, and also occurs in North America, according to Loew and Walker (see 

 Osten Sacken's Cat. of Dipt, of N. A., edit. 2d, p. 163). The larvae usually feed upon 

 decaying vegetable substances, as fungi, &c., but Schiner (Fauna Austriaca, Dipt,, 

 Vol. 1, p. 597) says, according to Bremi and Hartig, they also live-upon the larvae of 

 Lepidoptera and bees. It is a very interesting fact that they also eat the Cotton- 

 worms. Your American specimens «eem to be perfectly identical with my British 

 ones, but are rather smaller. I may add that the genus Cyrtoneura Macq. belongs 

 to the family of the true Muscidae."* 



There can be no doubt that the Cyrtoneuras we bred issued from pupae of Aletia, 

 but as the usual habits of the species are those of a scavenger, some doubt has arisen 

 in our mind as to whether it is a true parasite. We recall to our readers another 

 dipterous insect, the Fhora aletice Comstock, which has been called, by its describer, 

 one of the most important parasites of the Cotton-worm, and which nevertheless 

 turns out to be a mere scavenger. Cyrtoneura stahulans may, like this Phora, lay her 

 eggs on the decaying pupas of Aletia, which are so commonly met with at the time 

 the worms have defoliated the fields and have also eaten the leaves which sheltered 

 the chrysalides. These chrysalides when exposed to the light and heat of the sun 

 are very liable to rot, and on examining the chrysalides hanging on the defoliated 

 plants, by far the larger portion of them will be found to be rotten, many containing 



* See also Mr. Meade's note on the same subject in the (London) Entomologist, June, 1882, pp. 

 140-141. 



