HYMENOPTERA 357 



of the true ants, although there is sometimes a constriction between the 



first and second abdominal segments (Fig. 601). The body is often 



densely clothed with hair, which gives the insects the 



appearance of being clothed in velvet; and as the body ^S^feM&^ 



is usually ringed or spotted with two or more strongly ^T ^\^^) 



contrasting colors, they are very conspicuous. But in many 



species the body is naked. The colors most commonly 



worn by the velvet-ants are black and scarlet. The males are winged and 



frequent flowers. The females are wingless, but they run very rapidly 



and they sting severely. In the western states there are many straw 



yellow species, which are nocturnal. 



These insects are abundant in the warmer portions of our country, 

 and several species occur in the North. A large species, Dasymiitilla 

 occidentalism which measures from \ to \\ inches or more in length, is 

 known in the South as the " cow-killer ant " because of the popular 

 superstition that its sting is very dangerous to live stock. 



The mutillids of which the habits have been observed are parasites of 

 nest-building Hymenoptera in the cells of which they deposit their eggs. 

 The larvae attack those of the owners of the nest without touching the 

 provisions which the cell may contain. 



Family Scoliid^e 

 The Scoliids 



The scoliids are quite closely related to the preceding family but dif- 

 fer in their general appearance, resembling wasps rather than ants. 

 They are parasitic on white grubs, the larvae of Scarabaeidae. In their 

 habits they do not exhibit as much intelligence as do most digger wasps; 

 for they do not build nests and transport prey to them for their carniv- 

 orous larvae. Instead of this they dig in the ground where the white 

 grubs are, and finding one they sting it in order to paralyze it, work out 

 a crude cell about it, and attach an egg to a ventral abdominal segment of 

 the grub. The larva of the scoliid consumes the grub and then spins a 

 cocoon and completes its development in this place. 



The members of this family are very striking in appearance, being of 

 large size and with the abdomen marked with conspicuous spots. Two 

 genera are represented in our fauna, Scolia and Campsomeris (Elis). 



Family Formicid^e 

 The Ants 



The great number of ants and their wide distribution render them the 

 most familiar of all insects except perhaps the housefly. As has been 

 said by Professor Wheeler, an indefatigable investigator of these insects, 

 " Ants are to be found everywhere, from the arctic regions to the tropics, 

 from timberline on the loftiest mountains to the shifting sands of dunes 

 and seashores, and from the dampest forests to the driest deserts. Not 

 only do they outnumber in individuals all other terrestrial animals, but 

 their colonies even in very circumscribed localities often defy enumera- 

 tion." The present time has been termed the " age of insects " and of 

 all insects the Formicidae is the dominant family. 



