POND WEED TENT-MAKER. 177 



first which he examined, an elevation of an oval 

 shape, which was formed out of a leaf of the same 

 plant. He carefully examined it, and discovered 

 that threads of silk were attached to this elevation. 

 Breaking the threads, he raised up one of the ends, 

 and saw a cavity in which a caterpillar [Hydrocampa 

 Potamogata) was lodged. An indefatigable ob- 

 server, such as M. R''aumur, would naturally follow 

 up this discovery; and he has accordingly given us 

 a memoir of the pondweed tent-maker, distinguished 

 by his usual minute accuracy. 



In order to make a new cocoon, the caterpillar 

 fastens itself on the underside of a leaf of the Poia- 

 tnogetoit. With its mandibles it pierces some part of 

 this leaf, and afterwards gradually gnaws a curve 

 line, marking the form of the piece which it wishes to 

 detach. When the caterpillar has cut off, as from a piece 

 of cloth, a patch of leaf of the size and shape suited 

 to its purpose, it is provided with half of the mate- 

 rials requisite for making a tent. It takes hold of 

 this piece by its mandibles, and conveys it to the 

 situation on the underside of its own, or another 

 leaf, whichever is found most appropriate. It is there 

 disposed, in such a manner, that the underpart of 

 the patch — the side which was the underpart of the 

 entire leaf — is turned towards the underpart of the 

 new leaf, so that the inner walls of the cocoon are 

 always made by the underpart of two portions of 

 leaf. The leaves of the potamogeton are a little con- 

 cave on the underside ; and thus the caterpillar pro- 

 duces a hollow cell, though the rims are united. 



The caterpillar secures the leaf in its position by 

 threads of white silk. It then weaves a cocoon in 

 the cavity which is somewhat thin, but of very close 

 tissue. There it shuts itself up to appear again only 

 in the form of the perfect insect, and is soon trans- 

 formed into a chrysalis. In this cocoon of silk no 



