38 HOUSEHOLD INSECTS 



THE CLUSTER-FLY 



Pollenia rudis 



The cluster-fly is well-known to most housekeepers 

 because of its habit of entering houses in the autumn and 

 hiding away in protected nooks in large groups or clusters. 

 We have seen a handful of these flies in single clusters in the 

 corners of rooms and beneath garments hung up in closets 

 and beneath curtains at the windows of seldom used rooms. 

 They are a nuisance and a source of considerable annoyance, 

 not from the damage they do, for this is evidently slight, 

 but because of their presence. They are not welcome 

 guests at any time. 



The cluster-fly is an European insect and it was known 

 there at least a century ago. Just how or when it came 

 to this country is not known. It could easily have come 

 to this country on board ships, for it would as readily 

 enter a ship lying in port on an autumn day as a dwelling 

 house. From its habit of hibernating in clusters all 

 winter it could take several rides back and forth across 

 the ocean before spring. Loew mentions it in a list of 

 flies published in 1864 as common to Europe and America 

 so that it was here some years before that date, at least. 



Appearance of the fly. — It is slightly larger than the 

 house-fly and appears longer and narrower. This is 

 because the wings, when in repose, overlap each other, 

 thus bringing the outer edge of each almost parallel with 

 the sides of the abdomen. This position of the wings 

 gives the effect of narrowness when viewed from above 

 (Fig. 15). The wings of the house-fly when in repose 

 stand out at a considerable angle to the abdomen. More- 



