PSYCHK. 



A PROBABLE NEW TYPE OF IIYPERMETAMORPHOSIS. 



BY JAMES G. NEEDHAM, LAKE FOREST, ILL. 



While collecting stone-Hies in ]<"all 

 Creek at Ithaca, N. Y., in July, 1901, I 

 found attached to some of the smaller 

 stones in the edges of the current num- 

 erous larval and pupal cases of micro- 

 caddis-flies. I was not at first entirely 

 certain that they were caddis-fly cases : 

 but I took a few of them into the labo- 

 ratory and examined their contents. 

 One contained a larva of the form shown 

 in fig. I, easily referable to the family 

 Hydroptilidae of Trichoptera ; one con- 

 tained a transforming larva {prepupa : 

 subtiymplia) of the form shown in fig. 2 

 — a form so unusual in this family as to 

 awaken immediate interest ; and the re- 

 mainder contained pupae. The cases 

 were 3 mm. long, of the form shown in 

 fig. 5, elongate oval, with a process at 

 each end for attachment to the stone, 

 thin, fiat, of a yellowish brown color, 

 and so translucent that the stage of 

 development of the contained animal 

 could be easily recognized under the 

 microscope before opening them. Such 

 cases have not hitherto been known for 

 caddis-fly larvae : they probably repre- 

 sent a genus of Hydroptilidae for which* 

 the immature stages have not been 

 described — perhaps Phryxicoma, to 



which genus the two lone American 

 specimens of which our literature treats, 

 have been referred. 



I was then .so fully occupied with the 

 study of other aquatic insects that I 

 could give but little time or attention to 

 these : but I wished to see more of that 

 singular prepupa, and I managed to 

 spend an hour on the iith of July 

 collecting especially for it. I found the 

 cases everyw'here on the vertical sur- 

 faces of stones washed by a swift current, 

 and had no difficulty in gathering for 

 preservation several dozen of them. 

 Recently I have studied this material. 

 It contained three larvae of the sort 

 shown in fig. i, three prepupae of the 

 form shown in fig. 2 and a very large 

 number of pupae with the general 

 appearance sketchily shown in fig. 5. 

 The small number found in the earlier 

 stages, and the considerable number of 

 empty cases found, showed the season 

 of transformation was well advanced. 

 Two of the larvae were still active when 

 collected : I saw them moving freely 

 within their cases, though the apertures 

 at the ends seemed to be already closed. 

 Most Hydroptilid larvae carry their cases 

 with the thin edge upward, and in trans- 



