COLEOPTERA 



497 



bceoid larva grows apace, its head being constantly bathed in the rich 

 juices of the locust eggs, which it rapidly sucks or more or less com- 

 pletely devours. In another week it forsakes the remnants of the 

 locust egg-mass and forms a smooth cavity in the soil a short distance 

 from it. The larva then molts; the skin is not shed entirely, but 

 remains attached to the caudal end of the body (Fig. 587, C). The 

 new skin of the larva becomes rigid and of a deeper yellow color, 

 reminding one of a puparium of a dipterous insect; this instar, the 

 fifth, is termed the coarctate larva. The insect has the power of re- 

 maining in this coarctate larval condition for a long time, and gen- 

 erally thus hibernates. At the fifth molt the larva becomes active 

 again, and burrows about in the ground; it now resembles in form 

 the second scarabaeoid larva except that it is smaller and whiter; this, 

 the sixth instar, was termed by Riley the scolytoid larva. In the cases 

 observed by Riley, the scolytoid larvae did not feed but transformed 

 to pupse (Fig. 587, E) in the course of a few days. The pupa state 

 lasted five or six days. 



More than two hundred species of blister-beetles have been 

 found in this country; but by far the greater number of these are 

 confined to the western half of this region. Our most com- 

 mon species in the East belong to the genus Epicauta. 

 These insects feed in the adult state on the leaves of 

 various plants, but especially those of potato, and upon 

 the pollen of goldenrod; the larv«, so far as is known, 

 are parasitic in the egg-pods of locusts {Melanophis). In 

 addition to Epicauta vittdta, discussed above, our more 

 common species are the Pennsylvania blister-beetle, Epi- 

 cauta pennsylvdnica, which is of a uniform black color 

 (Fig. 588); and Epicauta cinerea, which is sometimes 

 clothed throughout with an ash-colored pubescence, and sometimes the 

 wing-covers are black, except a narrow gray margin ; the two varieties 

 were formerly considered distinct species ; 

 the first is commonly known as the gray 

 blister-beetle, the last as the margined 

 blister-beetle. 



Closely allied to the beetles mentioned 

 above are those of the genus Macrohasis. 

 The most common species of this genus 

 found in the East is Macrohasis ttnicolor. 

 This beetle measures from 8 mm. to 15 

 mm. in length; it is represented, enlarged, 

 in Figure 589; it is black, but rather 

 densely clothed with grayish hairs, which 

 give an ashen hue to the upper surface; 

 it is known as the ashy-gray blister-beetle. 

 The beetles of the genus Meloe present 

 an exception to the characters of the 

 Coleootera in that the wing-covers, instead of meeting in a straight 



I 



Fig. 



Fig. 589. 



