THEIR RELATION TO EACH OTHER 97 



between the segments. The young are minute, active 

 creatures Hke those of the bHster beetles, and run 

 about freely until they find some suitable host in which 

 their future development may be continued. Then 

 they lose their feet and prominent jaws, becoming 

 grub-like and inactive as the necessity for seeking 

 food is removed. 



The blister beetles or Meloidcv are semiparasitic 

 in habit and are quite numerous in specimens and 

 species. Some of them live in the egg-pods of grass- 

 hoppers and others in the nests of digger bees, chiefly 

 Andrenidce, feeding on the food stored by their hosts 

 and, incidentally, devouring the egg or young larva 

 of the bee. These blister beetles will be referred to 

 again in their relation to man, but in their relation to 

 the insects upon which the larvae feed they rank as most 

 effective checks. The female beetle lays her eggs on 

 flowers or on the ground as the case may be, and the 

 resulting larvae are active creatures with long legs 

 and large jaws known as " triungulins. " These are 

 able to go for long periods without food and they seek 

 either a grasshopper egg-pod or some plant or flower 

 frequented by bees, as the need may be. The forms 

 that hunt egg-pods, when they succeed in finding one, 

 immediately begin to feed. The forms that wait for 

 bees attach themselves to almost any hairy insect 

 that comes along and the lucky specimen that gets 

 upon a bee of the right kind is carried by it into its 

 burrow. When the bee with its burden of pollen plus 

 the parasite gets into the cell which it is filling with 

 food for its larva, the triungulin slips off, devours the 

 egg of its host as soon as laid, and that suffices to 

 bring it to the end of the first stage. From this point 

 the changes in both kinds of larvas are similar. They 

 are in direct contact with abundant food, the legs 

 7 



