822 



AN INTRODUCTION TO ENTOMOLOGY 



it has come to have a specific meaning distinct from its original one 

 It is like the word blackbern^; some blackberries are white, and not 

 all berries that are black are blackberries. 



In this family the body is short and stout; the thorax is much 

 arched, giving the fly a humpbacked appearance (Fig. 1043) ; and the 

 legs are comparatively short. The antennse 

 are scarcely longer than the head and are 

 eleven jointed; the segments of the flagellum 

 are short and closely pressed together (Fig. 

 1044), they are clothed with fine hairs, but do 

 not bear whorls of long hairs. The ocelli are 

 absent. In the male the eyes are very large 

 and contiguous, and divided; the upper half of 

 each has the facets very much larger than the Fig. 1044. 

 lower, from which they are distinctly divided 

 by a horizontal line. The upper half of each is doubtless a night-eye, 

 while the lower half is a day-eye. In the female, the eye facets are of 

 almost uniform size ; and the two eyes are widely separated. The pro- 

 boscis is not elongated, the small labella are homy, and the palpi are 



2d A 

 Fig. 1045. — Wing of Simulium. 



four-jointed. The wings are broad, iridescent, and not clothed with 

 hairs. The veins near the costal border are stout; those on the other 

 parts of the wing are vestigial (Fig. 1045), and are usually represented 

 merely by folds.* 



The females of many species suck blood and are well-known 

 pests. Unlike mosquitoes and midges, the black-flies like heat and 

 strong light. They are often seen in large numbers disporting them- 

 selves in the brightest sunshine. 



*The forked fold that I believe to be a vestige of vein Cu is not so regarded by 

 some writers, who refer to it as the fold between media and cubitus and label two 

 folds of the anal area as cubitus. I can see no reason for this conclusion; in no 

 other flies that 1 have studied is there a fold between media and cubitus. 



