386 THE ENTOMOLOGIST. 



the larvae of the small minmg Diptera {Phytomyzidm, &c.). If 

 these leaves are gathered while the larvae are at work, and 

 kept in a moist i^lace, — as a wide-mouthed bottle with some 

 damp earth at the bottom, or in a glass-topped box, — the 

 gatherer will in time be rewarded by the emergence of the 

 imago, which is often of great beauty, as the Trypeta Zoc, which 

 mines the leaves of the ragwort and groundsel, or the Acidm 

 heradei, which blotches those of the garden celery. Most of 

 these flies are double-brooded, and the leaves gathered in the 

 beginning of summer will produce the perfect insects in about a 

 month, while from those collected in the autumn or latter part of 

 summer no flies must be expected to emerge until the following 

 sj)ring. 



My friend Mr. Inchbald is quite, an enthusiast in this 

 department, and I have been enabled to clear up the life-history 

 of several interesting species by means of his investigations. 



It is not to the subject of mining Diptera, however, that I 

 now seek to direct especial attention, but to another tribe of 

 equal interest, — that of parasites ; those flies, for instance, 

 which pass the first and most important stage of their existence 

 in eating the bodies of other insects, especially of Lepidoptera, 

 whose larvfe they destroy, and thus perform a very useful work 

 in Nature, though one not always appreciated by the collector. 



The parasitic class of insects is a very large one, and a great 

 part of it consists of Hymenoptera. I am glad to sa}^ that this 

 division has lately received much attention, especially at the 

 hands of Messrs. Fitch and Bridgman. The dipterous parasites, 

 on the contrary, are very little known ; and the family of the 

 TachinidcE is the most difficult one to study in the whole order of 

 Diptera. A large number of these flies have been described and 

 named, but very few have been traced to their origin. If lepi- 

 dopterists would carefully preserve all that they breed from the 

 pupae of moths or butterflies, and note the species from which 

 each one emerged, the life-history of this interesting family 

 might soon be rescued from its present obscurity. I will gladly 

 endeavour to name any specimens so bred, if they are forwarded 

 to me. 



With the exception of a list of Euroijean Tacliimdcs and their 

 feeders, arranged side by side, which was compiled by the late 

 Francis Walker, and published in the ' Cistula Entomologica ' 



