THE CANADIAN ENTOMOLOGIST 117 



NOTES ON ITHYTRICHIA CONFUSA MORTON.* 



BY J. T. LLOYD, TTHACA, X. Y. 



To the family Hydroptilidae, the most minute of all Trichoptera, 

 belong the most oddly formed larva; of the order. Ithytrichia 

 lameJlaris, of Europe, with fiat form and laterally extended ab- 

 dominal segments, and the more common types with swollen 

 abdomens are noticeable departures from the usual cylindrical 

 form of Trichopterous larva\ The species under discussion, 

 Ithytrichia confusa Morton, kindly determined for me by Mr. 

 Kenneth Morton, belongs to the class with swollen abdomens, 

 but carries the peculiarity to the greatest extreme. So much 

 enlarged is the abdomen that the creature, if removed from its 

 case and placed on its back, is unable to aright itself, and only 

 under the most favourable conditions of still water can it, with 

 its comparatively feeble thorax and legs, drag its great abdomen 

 slowly about. In spite of its helplessness when removed from its 

 case, the specialized case-building habits of the species adapt it 

 to life in swift water. Its habits and life-history are described 

 more in detail on the following pages. 



Habitat. — In December, 1911, my attention was called to 

 small ovals of silk which were abundant, tightly cemented to 

 rocks in swift water of Cascadilla Creek on the Cornell Campus. 

 Examination proved that these cases contained the peculiar larvae 

 which later proved to be /. confusa. At the time of their discovery 

 the cases were all securely fastened to the stones, occurring, ap- 

 parently, in equal abundance on top, sides, and, when space 

 allowed, on the bottoms of their supports. At this time the creek 

 was at its winter level, which it had assumed two or three months 

 earlier, with the coming of the fall rains. The water was several 

 inches higher than its usual summer level, when rocks and boulders 

 everywhere protrude from the surface and one can almost step 

 across its breadth. In spite of the facts that the water was much 

 higher than when the eggs were deposited (the adults emerge in 

 Aiay) and that the cases, as we know them, are not portable, they 

 were often found at slight depth, on rocks that had previously 

 been completely above water and exposed to the intense glare of 



*Contribution from the Limnological Laboratory of the Department of 

 Entomology in Cornell University. 



April. 1915 



