FOOD OF INSECTS. 431 



fall into it, its prey consists chiefly of apterous species, 

 of which ants form by far the largest portion, with oc- 

 casionally an unwary spider or wood-louse. When the 

 full period of its growth is attained it retires under the 

 sand ; spins with its anus a silken cocoon ; remains a 

 chrysalis a few weeks ; and then breaks forth a four- 

 winged insect resembling, as before observed, the dra- 

 gon-fly both in appearance and manners, and preying in 

 like manner on moths, butterflies, and other insects*. 



The larva of Myrvielcon Formicaleo is not the only in- 

 sect which avails itself of a trap for obtaining its prey. 

 A plan in most respects similar is adopted by that of a 

 fly [Leptis Vermileo) in form somewhat resembling the 

 common flesh maggot. This also digs a funnel-shaped 

 cavity in loose earth or sand, but deeper in proportion 

 to its width than that of M. Formicaleo, and excavated 

 not by regular circles, but by throwing out the earth 

 obliquely on all sides. When its trap is finished, it 

 stretches itself near the bottom, remaining stiff" and with- 

 out motion like a piece of wood, and the last segment 

 bent at an angle with the rest, so as to form a strong 

 point of support in the struggles which it often neces- 

 sarily has with vigorous prey. The moment an insect 

 falls into the pitfall, the larva writhes itself round it like 

 a serpent, transfixes it with its mandibles, and sucks its 

 juices at its ease. If the insect escapes, the larva casts 

 above it jets of sand with surprising rapidity^. 



I am, &c. 



» Reaum. vi. 333-78. Bonnet, ii. 380. 



" Bonnet, ix. 414. De Gecr, vi. 168. /. 10. 



