120 INSECTS INJUKIOUS TO VEGETATION. 



The Cantharides are distinguished from all the preceding 

 insects by their feet, the hindmost pair of which have only four 

 joints, while the first and middle pairs are five-jointed. In this 

 respect they agree with many other beetles, such as clocks or 

 darkling beetles, meal-beetles, some of the mushroom-beetles, 

 flat bark-beetles, and the like, with which they form a large 

 and distinct section of Coleopterous insects. The following 

 are the most striking peculiarities of the family to which the 

 blistering beetles belong. The head is broad and nearly heart- 

 shaped, and it is joined to the thorax by a narrow neck. The 

 antennae are rather long and tapering, sometimes knotted in 

 the middle, particularly in the males. The thorax varies in 

 form, but is generally much narrower than the wing-covers. 

 The latter are soft and flexible, more or less bent down at the 

 sides of the body, usually long and narrow, sometimes short 

 and overlapping on their inner edges. The legs are long and 

 slender ; the soles of the feet are not broad, and are not cush- 

 ioned beneath ; and the claws are split to the bottom, or double, 

 so that there appear to be four claws to each foot. The body 

 is quite soft, and when handled, a yellowish fluid, of a disa- 

 greeable smell, comes out of the joints. These beetles are 

 timid insects, and when alarmed they draw up their legs and 

 feign themselves dead. Nearly all of them have the power of 

 raising blisters when applied to the sldn, and they retain it 

 even when dead and perfectly dry. It is chiefly this property 

 that renders them valuable to physicians. Four of our native 

 Cantharides have been thus successfully employed, and are 

 found to be as powerful in their effects as the imported species. 

 For further particulars relative to their use, the reader is re- 

 ferred to my account of them published in 1824, in the first 

 volume of " The Boston Journal of Philosophy, and the Arts," 

 and in the thirteenth volume of " The New England Medical 

 and Surgical Journal." 



Occasionally potato-vines are very much infested by two 

 or three kinds of Cantharides, swarms of which attack and 

 destroy the leaves during midsummer. One of these kinds 

 has thereby obtained the name of the potato-fly. It is the 



