MAY FLIES AM) MIDGKS OF NKNV YolIK 1)7 



GROUP CERATOPOGON Meigen 

 Illiger's Mag. 11:261. 1803 



This group may primarily be divided into two series; those 

 species having hairy wings belonging to one and those with bare 

 wings to the other. The larvae of the former group usually 

 live under bark, while those of the latter are aquatic. The 

 larvae of the first group may be characterized as follows: The 

 head is short, the antennae minute, the mouth parts are 

 small, and the mandibles apparently move in a more or less 

 vertical plane. The mandibles in some species have several 

 apical teeth (pi. 17, fig.G). The body consists of 12 well-marked 

 segments of which the first three, usually a little larger than 

 the following, belong to the thorax. The head, thorax, and 

 abdomen are provided with various spines, setae, and tubercles, 

 differing with the species. On the ventral surface of the first 

 thoracic segment is the anterior proleg, a short, more or less 

 cylindrical process,, divided into two branches, at the tip of each 

 of which is a crown of a few claws (pi. 17, fig.7). The last ab- 

 dominal segment has a pair of prolegs, each with a few bilobed 

 claws (pi. 17, fig.S). Blood gills appear to be present and consist 

 of delicate white filaments. The pupae of the members of this 

 group remain partly sticking in the larval skin, the thorax and 

 the first three or four abdominal segments projecting out (pi. 17, 

 fig.9). The thorax is large, prominent, the respiratory trumpets 

 (fig.9, t) when present are small and inconspicuous; the abdom- 

 inal segments variously armed with spines and setae. 



The eggs and the method of egg laying of several members of 

 the second group will subsequently be described. The larvae 

 of the second (aquatic) group swim well with a writhing 

 snake-like motion. They are usually whitish in color, slender, 

 12-jointed (not counting the head), the thoracic segments 

 shortest ; the middle abdominal segments of the greatest diam- 

 eter, and the last segments usually longest (pi. 17, fig.l). The 

 head is very small, somewhat elongate, oval, with a pair of eyes, 

 each eye consisting of one or two pigment spots. There are 

 usually a few setae upon the head. The antennae (pi. 18, figs.la 

 and 3a) are very small and inconspicuous, and in all species 

 which T have seen, two-jointed. Of the mouth parts the 



