i6o 



THE STUDY OF INSECTS 



apple, cherry, willow, and oak. The specimen figured here is a male; 

 in the female the mandibles are shorter. 



The giant stag-beetle, Lin amis elafhus, is a large species found in the 

 South. It measures from if inches to 2 inches in length, not including 

 the mandibles, which in the case of the male are more than half 

 as long as the body, and branched like the antlers of a stag. 

 The antelope-beetle, Dorcus parallel us. — This beetle is 

 somewhat smaller than the species of Lucanus, and differs 

 in having the wing-covers marked with longitudinal stria? 

 and the teeth on the outside of the fore tibiae much smaller 

 (Fig. 277). 



Several species of stag-beetles that are much smaller 

 Fie. 277. than Dorcus are found in this country. 



Family Passalid^e 



The members of this family resemble the stag-beetles in the form of 

 the antenna?, but differ in that the mentum is deeply 

 emarginate, with the ligula filling the emargination. 



A single, widely distributed species is found in the 

 United States; this is the horned passalus, Passalus 

 cormltus (Fig. 278). It is a large, shining, black bee- 

 tle, with a short horn, bent forwards, on the top of the 

 head. This beetle and its larva are found in decaying 

 wood. The larva appears to have only four legs, the 

 hind legs being shortened and modified so as to form 

 part of a stridulating organ. 



The beetles of this genus are common throughout 

 the tropics of both hemispheres. According to the 

 observations of Ohaus, which have been confirmed by 

 Professor Wheeler, these beetles are social. They form 

 colonies, consisting of a male and female and their progeny, and make 

 large, rough galleries in rather damp, rotten logs. The parent beetles 

 triturate the rotten wood and apparently treat it with some digestive 

 secretion which makes it a proper food for the larva?, since their mouth- 

 parts are too feebly developed to enable them to attack the wood directly. 

 All members of the colony are kept together by stridulatory signals. The 

 stridulatory organ of the adult consists of patches of minute denticles on 

 the dorsal surface of the abdomen, which may be rubbed against similar 

 structures on the lower surface of the wings. 



Fig. 278. 



Family Cerambycid^; 



The Long-homed Beetles or Cerambycids 



This is a very large family, there being more than eleven hundred 

 described species in North America alone. As a rule the beetles are of 

 medium or large size, and graceful in form; many species are beautiful 

 in color. The body is oblong, often cylindrical. The antenna? are long, 

 often longer than the whole body; but except in one genus, Prionus, they 

 are only eleven- jointed, as with most beetles. The legs are also long, and 



