INSECTS. 



215 



the larger species, when attracted by a light at night, will occasion con 

 erable alarm in a quiet household. The largest species of these water- 

 beetles belong to the same genus as the species figured. In these la 

 forms there are several interesting features. First is the peculiar egg-m-t 

 or cocoon shown in our cut. In this cocoon the female places a consider- 

 able number of eggs and then fastens it to some object floating on the 

 surface of the water. When the larva? hatch, they at first play the part of 

 cannibals, feeding upon their brothers and sisters in the same cocoon, bui 

 after they escape from the egg-nest they eat other forms. In their eating 

 their habits are very peculiar. The larva of the species figured takes the 

 insect which it has caught and holds it above the surface of the water. It 

 now crushes it, and lets the juices drop down into its mouth, which is held 

 just above the surface. 



The adults of all the water-beetles breathe air, and during their sojourn 

 below the surface of the water they depend on a supply 

 which they take down with them, either entangled in 

 the hairs which cover the body or held beneath the wing- 

 covers. 



The next group of beetles — the carabids of science, 

 the running beetles of the Germans — contains over ten 

 thousand species of active, predaceous insects, the major- 

 ity of which are to be regarded as of very beneficial 

 character. Some are small, others reach a very large 

 size, and most of them are eminently terrestrial, living 

 on the ground, where they seek their food. 



The bombardier beetles, of which there are some hun- 

 dred and fifty species, are interesting from their peculiar 



defensive apparatus which has given them their 

 *}' name. On either side of the vent is a gland which 



Fig. 212. 



Water-beetle 

 [Bytx 



Fig. 213. — Carabid beetles (Calosoma, Pasimachus, Harpalus). 



secretes a strong-smelling acrid liquid, which is converted into a gas as 



as it comes in contact with the air. When the beetle is alarmed, as is the 



