AQUATIC INSECTS IX XETV YORK STATE 367 



tense black, velvety witli a bluish luster; underside grayish. 

 Legs reddish with black tarsi. Wing hyaline, veins and base 

 bluish white. Abdomen; above, black with posterior margins 

 of segments edged with gray; undersides of segments 2 and 3 

 light, reddish gray, the others blackish, with gray posterior 

 margins. Sexual organs black. Thorax and abdomen very 

 sparsel}' clothed with white pubescence. Described from three 

 bred specimens. 



Larva. Length when full grown 5.5mm to 7mm. Normal 

 shape and general appearance differ from S. pecuarum by 

 the much more irregular markings of segments and head. A 

 majority of the larvae possess one or two lateral spots on club- 

 sbaped posterior third of body. Head lacks the regular arrange- 

 ment of spots and lines, which become confused; the two black 

 spots on each side present. Antennae uniformly pale, much 

 longer than in pecua rum, slender and three jointed; first 

 joint almost twice as long as joints 2 and 3 together, and a lit- 

 tle bent; at base three times and at tip twice as thick as second 

 joint, which is nearly uniform in width, tapering but yerj 

 slightly toward the tip; joint 3 small and pointed, about one 

 fifth as long as joint 2. Mentum similar to that of S. 

 p e c u a r u m, but distinguished by a flatter apex, by the pos- 

 session of three erect bristles on each side, starting from round 

 pores, which decrease in size toward base; a fourth very small 

 bristle close to base, and in line with the bristles above; the 

 sides of mentum have on each side four sharp teeth. Labrum 

 and labium not different from those of pecuarum. Mandi- 

 bles possess but seven teeth in the first row; the three first 

 nearly uniform in length; teeth 4 to 7 gradually decrease in 

 length; tooth 4 much the longest of all; the two teeth in the 

 second row similar to those of pecuarum. Maxillae and 

 maxillary palpus also similar. Fans similar, but the hairs lin- 

 ing the inside of the scythe-shaped rays are thicker and nearer 

 together. Prolegs, more slender, last joint bearing a crown 

 of hooks, usually bent suddenly toward head. Tip of abdomen 

 similar to that of pecuarum. Breathing organs quite dif- 

 ferent; the three main trunks branch each six times, and the 

 branches enter the trunk from both sides. Full grown larvae 

 show also the newly formed, coiled breathing tubes of the pupae 

 through their skin. Described from many specimens. 



Pupa. Average length 3.5mm; shape and colorations as in S. 

 pecuarum. The thoracic filaments consist only of the six 

 original rays, which do not branch. On dorsal surface of the 

 I>osterior margins of abdominal joints 4 and 5 is a row of eight 

 anteriorly curved hooks, similar to those of pecuarum, but 



