MICHIGAN ACADEMY OF SCIENCE. 77 



A REMEDY FOR THE BLACK FLY PEST IN CERTAIN STREAMS 

 OF THE SOUTHERN PENINSULA OF MICHIGAN. 



CORA D. REEVES.^ 



In June, 1009. members of the engineering staff of tlie University of 

 Michigan were driven from their camp on Douglas Lake in Clieboygan 

 county by tlie black flies and at the end of the month it was deemed 

 best to postpone for one week the opening of the Engineering Camp and 

 tlie Biological Station on Douglas Lake on account of these pests. The 

 conditions seemed to demand an immediate investigation and this was 

 undertaken by the writer at the suggestion of Professor Reighard and 

 under his direction. 



Eggs, larvae and adults were collected and determined as Sinnilium 

 venustum, an identification Avhich was kindly confirmed by Professor O. 

 H. Johannsen of the Maine Agricultural Experiment Station. No other 

 species of black fly was found. 



The adult is described by Comstock,- as about 5 mm. ( 1/5 in.) long, 

 a stout-bodied fly with iridescent wings and very short, though sharp, 

 biting mouth parts. The character of the mouth parts probably ac- 

 counts for the fact that the fly usually inflicts the bite on the neck, or 

 about the eyes or nose where the skin is thin. The few observations 

 made tend to confirm the belief that where adults are numerous their 

 breeding places are to be sought to windward and at no very gi'eat dis- 

 tances. The,y appear not to be strong fliers and are distributed from 

 their breeding grounds, in part at least, by the wind. Those at the 

 Engineering Camp came with little doubt from Carp Creek, a stream 

 less than a mile southwest of the camp and none were seen or heard of 

 more than two or three miles from a larva invested stream. 



Comstock^ tells of watching the adults dart into the water and out 

 again and of finding the surface of a submerged rock coated with their 

 eggs. The larvae are about 8 mm. (ly in.) long, club-shaped and aj:- 

 tached by the posterior, larger end to }<ome smooth solid, usually a rock. 

 They are aquatic like the larvae of other gnats and mosquitoes and are 

 found in swift water. They are usually to be obtained by sweeping the 

 surfaces of the rocks and catching the dislodged material in a net. As 

 there are no rocks in Carp 'Creep they were sought there by direct ob- 

 servation and by sweeping the logs and submerged branches, but with- 

 out success. They were finally discovered by picking out pieces of bark 

 which chanced to be' lodged in the stream and to the smooth inner sur- 

 faces of which they were attached. They were also found attached to 

 smooth leaves, such as those of the maple and beech which were caught 

 and held in the stream. Small, smooth branches and twigs were often 

 found covered with them. Thus a stick % in. in diameter and not over 

 four inches long had 221 larvae attached to it. They were found quite 

 uniformly on the under surface of the object to Avhich they were fast- 

 ened and if the supporting surface was wide, they were apt to be at- 



iContribution from the Zoological Laboratory of tlie University of Michigan, Xo. 129, 

 (Biological Station Series. Zoological Publication No. 1). 

 ^Comstock, J. II.. A Manual for the Study of Insects. 7th edition. Ithaca. 1907. 



