450 



THE STUDY OF INSECTS. 



thread-like antennae (Fig. 529). The abdomen, however, 

 is much longer than wide. The antennae (Fig. 530) are 



shorter than the thorax, and 

 composed of short, broad, 

 and closely-pressed-together 



segments. Although the an- 



o o 



FIG. 529. Bibio. 



FIG. 530. 



tennse are hairy, they are not 

 furnished with whorls of long 

 hairs in the males, as is the case in most of the preceding 

 families. These insects resemble the fungus-gnats in having 

 ocelli ; but they differ from them in the shortness of the 

 antennas and in the fact that the coxae are not greatly 

 elongate. In this family and the following one the eyes of 

 the males are in many cases contiguous. The venation of 

 the wings of the typical genus is represented by Figure 531. 



vn, 



VII, 



FIG. 531. Wing of Bibio. 



The adult flies are generally black and red, sometimes 

 yellow. They are most common in early spring ; which has 

 suggested the name March-flies ; but some occur later in the 

 season. 



The larvae vary in habits ; some species feed on decay- 

 ing vegetable matter, while others attack the roots of grow- 

 ing plants, especially of grass. They have ten pairs of 

 spiracles; which is an unusually large number, as but few 

 insects have more than nine pairs. The pupae are usually 

 free. 



