FLIES THAT FREQUENT HOUSES 39 



over, the thorax of the cluster-fly bears many short, 

 golden hairs. The thorax is of a uniform coloration and 

 lacks the light and dark lines on the thorax of the house- 

 fly. The abdomen is grayish but inclined to be iridescent, 

 and thickly set with hairs, especially at the posterior end 

 and along the sides. 



Its habits. Normally the cluster-fly lives out-of-doors, 

 frequenting the flowers and fruits of plants. In the 

 autumn, however, it enters dwelling-houses in search of 

 snug retreats in which to pass 

 the winter. It gathers in clus- 

 ters in the corners of unused, 

 darkened rooms, under clothing 

 in closets, beneath curtains at 

 windows, and in other nooks. 

 A correspondent writes, "Can 

 you give me information con- 

 cerning the house-fly which in 



late August and September gets ^ ^ _ Tfae duster . fly 

 into unused rooms where there (x 2|.) 



is no food or odor and bunches 



in the angles of the wall and behind pictures and fur- 

 niture ? They do not fly much but crawl about in a 

 lazy manner. Screens and every device which works 

 perfectly in excluding the ordinary fly are useless in 

 keeping these out." This letter describes the habits of 

 the cluster-fly admirably. 



W. H. Dall quotes from a letter of a relative living at 

 Geneva, New York, who had been much troubled with 

 these flies. Evidently the flies had been troublesome in 

 the neighborhood, for the letter says, " people soon learned 

 to look everywhere ; in beds, in pillow-slips, under table 



