COLLECTING FUNGUS-GNATS. 127 



remarks to the collection of these interesting insects. In the 

 :first pLace a word of warning may be necessary : The great 

 majority of the species are not, as Mr. Morley suggests, con- 

 spicuous and easy to name, but small, obscure and difficult of 

 determination without a close study of the male hypopygium. 



The places to look for them (apart from window-panes, 

 which, though not to be neglected, yield a comparatively small 

 number), are steep or overhanging banks in woods, or against 

 diffs, or at the mouths of small caves, especially if these 

 situations are damp ; also the steep overgrown banks of small 

 streams, especially in woods. By sweeping in such places it is 

 often possible to obtain many hundreds of specimens in a few 

 minutes. Provided that no heavier insects are taken with them 

 they may all be put into the killing-bottle together, and no 

 matter how tangled the mass may appear, it will be found on 

 shaking it out that only a small percentage have lost more than 

 one leg. They must not be left too long, however, before they 

 are pinned. 



The flower-heads of umbellifers are not in my experience 

 very extensively frequented except by members of the subfamily 

 Ceropiatinse, and this will perhaps account for Mr. Morley' s 

 /Curious opinion that this is " the most abundant group as 

 regards specimens." It is certainly the least abundant. 



Only a comparatively small number of species live as larvae 

 under decaying bark, most of these being Ceroplatinae. Practi- 

 cally nothing is known as to the life-history of the species of 

 Macrocera, which are common and conspicuous flies. 



The larvae of the others fall into two groups : those which 

 feed on the spores of fungi or moulds, especially those growing 

 on bark, or on liverworts ; and those which feed internally on 

 the substance of various fungi, chiefly Agarics. The first group 

 are exceedingly fragile and delicate, but not difficult to rear once 

 i;hey are safely home. They must not be allowed to become too 

 dry, but require plenty of air, or else they will succumb to mould. 

 The second group are more hardy and are easily reared, though 

 they suffer much from the attacks of parasites. They usually 

 pupate in a cocoon just below the surface of the ground, whereas 

 most of the others merely spin a slight web on the bark or 

 fungus on which they are feeding and pupate in it. 



There is still a great deal of work to be done on this family 

 in Britain, especially as regards the life-histories, and if anyone 

 feels sufficiently interested to breed specimens from the larvae 

 the writer will gladl}^ name the resulting flies. An extensive 

 work on the early stages of the family is being prepared by Dr. 

 P. Keilin, of Cambridge University, who, I have no doubt, will 

 welcome co-operation from any quarter. The present writer 

 hopes to be able to publish, in the not very distant future, tables 

 and keys to the known British species. 



