302 HALF HOUKS WITH INSECTS. [Packard. 



insects belong to the lowest division of the winged insects, 

 and, even geologically speaking, to a very ancient stock. It 

 is significant to find developed in them such a high degree 

 of architectural skill. 



The mechanical ingenuity of the case worms is shown in 

 the construction of their cases. Tliese are ancient types of 

 insect forms thought to be in some respects similar to those 

 occurring in the coal formation, while undoubted caddis- 

 flies occurred in the Wealden strata of the Lower Creta- 

 ceous formation. Sir Charles Lyell assures us that " a large 

 species of caddis-worm, which swarmed in the Eocene lakes 

 of Auvergne in France, was accustomed to attach to its 

 dwelling the shells of a small spiral univalve of the genus 

 Paludina." It must have resembled the cases of the British 

 Limnophilus Jlavicornis, whose case (Fig. 232) is covered 

 Fig "3" with little fresh Avater snail shells. Other 



examples of the work of these interesting 

 insects are given on page 132. They 

 gather bits of leaves or sticks, or particles 

 of gravel, Avith their jaws, and arransje 



Case worm. » ' j i o 



them around tlieir bod}', covering their 

 hind body first and then building on to the anterior end, 

 gluing the particles together by means of a silky secretion. 

 They probably do not use their fore legs in this process, at 

 least the clothes moth does not in constructing a similar 

 case. Other cases are made by rolling up a strip of leaf 

 deftly cut out of the required length and width, as seen in 

 Fig. 92, while others, more careless, attach broad, irregular 

 pieces to their cases. 



Another net-veined insect which shows much ingenuity in 

 the construction of its dwelling, and mucli low cunning in 

 providing itself with food, is the ant lion. This is the larva 

 of the Myrmeleo. Its body is broad and flat, armed with 

 enormous scissor-like jaws which project straiglit out from 

 the head. It lives in colonies, sometimes numbering over 



14 



