524 



AN INTRODUCTION TO ENTOMOLOGY 



Family PASSALID^ 



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

 of the antennae, 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 homed passalus, 

 Passalus cornutus (Fig. 633). It is a large, shining, 

 black beetle, with a short horn, bent forwards, on 

 the top of the head. This beetle and its larv^a 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. See Figure loi, page 8g. 



The beetles of this genus are common through- 

 out the tropics of both hemispheres. According 

 to the observations of Ohaus, which have been 

 ^33- confirmed by Professor Wheeler ('23), 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 larv£e, 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. 



Family 

 CERAMBYCID^ 



The Long-horned Beetles 

 or Ceranihycids 



This is a very large 

 family, there being more 

 than eleven hundred de- 

 scribed 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 antennae are long, often 



ABC 

 Fig. 634. — Tarsi of Phytophaga: A, typical; B, 

 Spondylis; C, Parandra. 



