man's chief competitors, the insects 55 



burrow or cell and the larva lives a happy and secluded life 

 slowly devouring the store of living but helpless creatures. 

 The great majority of these wasps select a special and restricted 

 type of food; some take only spiders, like the blue mud wasp 

 of our barns and attics and the "tarantula hawk" of the 

 southwest, others only certain kinds of flies, bees, grasshoppers, 

 crickets, cockroaches, certain t>T3es of caterpillars, etc., as the 

 case may be. The spiders know these murderers well, and 

 some of the web-spinning kinds will drop instantly to the 

 ground if they see or hear one. A large and powerful kind 

 feeds upon harvest-flies or cicadas, and not infrequently one 

 sees a cicada in full flight shrieking piteously with one of these 

 great wasps close behind it. 



The dehcate lace-winged flies, the commonest of which are 

 green with golden eyes and smell abominably, are savage 

 Httle brutes when young, feeding on other weaker and less 

 active insects, mostly aphids. They look something like the 

 larvae of the lady-bugs, w^hich have the same habits, but have 

 much longer and more slender jaws. The female lace-winged 

 fly lays her eggs in groups, each small white egg raised on a 

 long and slender stalk so that when they hatch the young can- 

 not eat each other. 



The ant-lions, related to the lace-winged flies, have some- 

 what similar though larger and much stouter, young, which 

 mostly construct funnel-shaped traps in loose earth or sand into 

 which small insects fafl; some of them do not make traps 

 but stroll about after the manner of young carabid beetles. 



The maggots of the syrphid flies, those little flies which 

 hover in the air and dart from place to place, are mostly aphid 

 feeders, and you often see them in the aphid colonies. Though 

 soft and blind and legless they seem to prosper well in spite of 

 competition by stronger and much more active creatures. 



Several of the small lycaenid butterflies as caterpillars live 

 on scale insects or on ants, and various small moths live on 

 the excretions of scale insects, lantern bugs, etc. Near Bos- 

 ton I once gathered quantities of these predaceous caterpillars 



