14 



THE GENUS PLATYPUS. 





Fig. 1. — Section of an orange trunk, showing galleries of Platypus 

 compositus — greatly reduced (original). 



The species of this genus are among the largest, strongest, and most 

 destructive of the ambrosia beetles in the United States. They are 



readily known by their 

 very long cylindrical 

 bodies, their promi- 

 nent heads, flattened 

 in front, the flattened 

 and spur-tipped joiut 

 of the front legs, and 

 in the males the spine- 

 like projections of the 

 wing-cases behind. 



They are powerful 

 excavators, generally 

 selecting the trunks of 

 large trees, and driv- 

 ing their galleries deep 

 into the heart wood. 

 The section of an orange trunk shown in fig. 1 indicates how extensive 

 their galleries sometimes become. 



The female is frequently accompanied by several males, and as they 

 are savage fighters, fierce sexual contests take place, as 

 a result of which the galleries are often strewn with the 

 fragments of the vanquished. The projecting spines at 

 the end of the wing-cases are very effective weapons in 

 these fights. With their aid a beetle attacked in the rear 

 can make a good defense and frequently by a lucky stroke 

 is able to dislocate the outstretched neck of his enemy. 

 The females produce from 100 to 200 elongate-oval 

 pearl-white eggs, which they deposit, in clusters of 10 or 

 12, loosely in the galleries. 



The young require five or six . t , -__ ___. ,,----■ 

 weeks for their development. They Y" P 

 wander freely about in the pass- 

 ages and feed in company upon the 

 ambrosia which grows here and 

 there upon the walls. The adult 

 larva is represented in fig. 2 (lower 

 fig.), while fig. 3 (upper fig.) exhibits in greatly enlarged detail the 

 chitinous ridges upon the thoracic segment. These ridges, together 

 with the row of tubercles upon the other segments, enable the larva 

 to move as rapidly through the galleries as if it were possessed of well- 

 formed legs. The details of the mouth parts seen in fig. 3 show that 



1 I ' 



Fig. 2 



Platypus compositus : Upper figure, imago ; 

 lower figure, full-grown larva — enlarged (origi- 

 nal). 



