278 



which the pup.T may have crawled. Because of the habit which the 

 species of this subfamily have of ascending beyond the water-level 

 before emergence of the imago they necessarily remain longer at the 

 surface, which affords a better opportunity for collecting them. 



Imagines of Chironomidcv may be obtained throughout almost the 

 entire year. Ceratopogomncc rarely fly in the well-known "cloud" which 

 is characteristic of many species in Cliironomin(F, but occasionally 

 species of the genus Porcipouiyia may be seen flying in large numbers 

 close to the trunks of old trees. The writer has commonly taken F. 

 pilosa in such situations, both sexes being represented. It is a pecu- 

 liar iKibit of both the terrestrial and aquatic members of this subfamily 

 to pass the heat of the day in thick vegetation. In the case of the bit- 

 ing species of Ciilicoidcs at least, I have found that there is a prefer- 

 ence for evergreens, or at least for those having the leaves very closely 

 placed, such as juniper or spruce. At almost any time during the year 

 specimens of this group may be obtained in suitable localities by beat- 

 ing such trees in the usual manner adopted by collectors. The Tany- 

 pince and Chironornincr are readily obtained almost anywhere, on win- 

 dows in the daytime, by sweeping vegetation close to streams, or at 

 lighted windows at night. There are very few species of Chironomida: 

 that can not be found at light, and ciuite a number of species which are 

 generally considered rare have been taken by Mr. C. A. Hart, of this 

 ofiice, and the writer, on store windows in various towns in Illinois. 



METHODS OF REARING 



It has not been possible for me to experiment extensively with live 

 material, but a fair measure of success has been obtained in rearing 

 species by the simple expedient of placing single larvae in two-dram 

 vials about a third full of water, in which was placed a small portion 

 of the mud or dead leaves from the habitat of the larva, the mouth of 

 the vial being closed with a plug of cotton. It is not to be expected, 

 however, that this method will prove successful in the case of larvae 

 which live in swift-running streams, and several species which were 

 obtained from this sort of habitat never reached maturity. Mr. Hart 

 met with considerable success with larvae contained in fine gauze rear- 

 ing-cages which were moored in the Illinois River. This method is 

 the ideal one and should be adopted by any one who is intending to 

 study the biology of Chironomidcc. 



METHODS OF PRESERVATION 



Larvie of all the Chironomidcc may best be preserved in vials con- 

 taining 85 per cent, alcc^hol. It is necessarv to boil the larvae first to 



