AQUATIC INSECTS IN NEW YORK STATE 367 
tense black, velvety with a bluish luster; underside grayish. 
Legs reddish with black tarsi. Wing hyaline, veins and base 
bluish white. Abdomen; above, black with posterior margins 
ef 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 
sparsely 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- 
Shaped 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 nm 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 very 
slightly toward the tip; joint 3 small and pointed, about one 
fifth as long as joint 2. Mentum similar to that of S. 
pecuarum, 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 laryae 
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 
posterior margins of abdominal joints 4 and 5 is a row of eight 
anteriorly curved hooks, similar to those of pecuarum, but 
