154 



HARDWICKE'S SCIENCE-GOSSIP. 



[July 1, 1S6S. 



often mistaken for Micro-Lepidoptera, construct 

 little flattened seed-like cases almost L wholly of 

 silk, with a slight external coating of sandy 

 particles. 



All the cases of which I have yet spoken are 

 portable, and are carried about by the inmate from 

 place to place, being fixed to stones or water-plants 

 when the metamorphosis to the pupal condition is 



Ceylon Cases. 



about to take place. But there is yet another class 

 of cases. Almost any time during the year, if we 

 lift up a moderately large stone at the bottom of a 

 stream, we see attached thereto what appear to be 

 elongately-oval masses of small angular stony frag- 

 ments, arranged without any particular order. 



Fig. 161. 

 Case of Hydroptila. 



Fig. 162. Case of Rhyacophila. 



These are the cases formed by the species of Ey- 

 dropsychidce and Bliyacophilidce, and are constantly 

 fixed. The species of Rhyacophila can sometimes 

 be scarcely said to form a case at all when in the 

 larval condition, living almost free under stones, 

 and constructing a case only when about to change. 

 The RkyacopJdlidce are remarkable for the pupa 

 being contained in an elongate brown cocoon inside 

 the case ; in all others the pupa lies free. 



I have ineviously mentioned that there are one 

 or two exceptions (which prove the rule) to the 

 aquatic habits of Caddis-worms. The authenti- 

 cated instance is that of Enoicyla piisilla, the larva 

 of which lives in a slightly-curved sand-tube amongst 

 the moss at the roots of trees. This has not been 

 considered a British insect ; but, almost at the 

 instant of penning this paper, I have received from 

 Mr. Fletcher, of Worcester, larva; and their cases 

 which I scarcely hesitate to attribute to E. pusilla. 

 He found them near the roots of willows. The 



female of this exceptional species, as regards habit, 

 is exceptionable otherwise, inasmuch as she is 

 wingless. My larvae are, as might be expected, 

 destitute of the usual branchial filaments, and 

 probably breathe by means of spiracles, as do 

 caterpillars. 



104. 

 Figs. 163, 164. Cases of Halesus digitatus. 



It now remains to me to speak briefly of a pecu- 

 liar instance of form belonging to extra-British 

 species. In the streams of Southern Continental 

 Europe, and of various other parts of the world, are 

 to be found little cases formed in shape of a small 

 snail-shell. These are termed Helicopsyclie, and have 

 only recently been proved to be the work of Caddis- 

 worms, they having been repeatedly described as 

 the shells of Mollusca, under various names. Caddis- 

 worms have six legs, attached to the three thoracic 

 segments, which, with the head, are of a horny tex- 

 ture above, these forming that portion of the body 

 protruded when the creature is feeding ; the abdo- 

 men is soft, the first segment usually carrying three 

 humps, one median, and one on each side, which 

 serve, with the assistance of the hooks at the 

 extremity, to prevent the larva being dragged from 

 its case ; so that it is often impossible to eject 

 without introducing a twig into the tail-end and 

 pushing it forward. They breathe by means of 

 branchial filaments, usually placed along each side 

 of the body ; but for details on the anatomy I must 

 refer the reader to Pictet's magnificent work, 

 " Recherchcs sur les Phryganides." The water is 

 admitted into the case by means of a silken grating. 

 Their food, as a rule, consists of vegetable matters, 

 but some are certainly more or less carnivorous, 

 and they have been accused of destroying salmon- 

 fry, with what justice I know not. 



I have but few suggestions to offer as to breeding 

 these insects, having been, as a rule, signally unsuc- 

 cessful ; but Pictet managed to rear numerous 

 species, of which he figures the metamorphoses. 

 Those that frequent still waters should not be diffi- 



