AQUATIC INSECTS IN THE ADIRONDACKS 



473 



Labium short and stout, median lobe with a narrow median cleft and 

 denticulate margin ; lateral lobes truncate on end, scarcely denticulate : 

 no raptorial setae. 



Legs stout, with prominent, twisted, hair-fringed, longitudinal carinae ; 

 tarsi 3-3-3 jointed. 



Wing cases laid parallel along the back, their apices reaching the mid- 

 dle of the fifth segment. 



Abdomen tapering beyond the fifth segment with thin flaring lateral 

 margins showing on each of segments 4-9 an angle at the middle and a 

 flat tooth at the apex, and with a dorsal row of hairy tubercles on seg- 

 ments 5-9, parallel to the lateral margin but nearer the median line : ap- 

 pendages obtuse, the superior with a broad, shallow, apical emargination. 



The eggs are deposited in wet, boggy places, when there is hardly any 



water standing, and the nymph lives in the mud in such places. 



Subfamily cordxjIvEgasterimae 



A small group of large species, inhabiting mainly clear streams that 

 flow through upland marshes, spring bogs, etc. The images are strong 

 of flight, and are oftenest seen cours- 

 ing back and forth over some small 

 stream, flying on a regular beat, and 

 passing and repassing the same 

 point at intervals of a few minutes. 

 The collector may take advantage 

 of this habit, and so station himself 

 that he may reach the specimen as 

 it passes, and capture it, if dextrous 

 with a net. 



The nymphs live on the bottom 

 in shallow water, buried in clean 

 sand or in vegetable silt. Though 



buried they do not burrow, but descend by raking the sand from beneath 

 them by sweeping, lateral movements of the legs. When deep enough, 

 they kick the sand up over the back till only the elevated tips of the eyes 

 and the respiratory aperture at the tip of the abdomen are exposed. By 

 placing a live nymph in a dish of sand and water and watching, its 

 method may be observed in a very few minutes. The whole comical 

 performance reminds one strongly of the descent of an old hen in a 

 dustbath. 



Once adjusted in the sand, a nymph (unless food tempts) remains 

 motionless a very long time. In a dish of sand on my table, I have had a 

 nymph remain without change of position for weeks, no food being 

 offered it. Let any little insect walk or swim near the nymph's head, 



Fig. 15 Tachoptery X thoreyl Selys ; a la 

 bium and b antenna of a female nympli ( Mr 

 Williamson's type ) 



