70 OUTLINES OF ENTOMOLOGY. 



[Fig. 29.] The Heteromerous beetles are separated into quite a 



number of families, of which two only are of especial inter- 

 est to the economic entomologist, viz.: The Oil or Blister 

 beetles (MELOIDJE) and the Meal beetles (TENEBRIONIDJE). 

 The Blister beetles are rather elegantly formed insects and 

 differ from all others in having the somewhat triangular 

 head set on vertically with a distinct neck. The wing covers 

 Riiey 6 " and entire body wall are rather thin and leathery. The 

 colors are satin black or plain ash-gray, or black, margined with pale 

 gray, or striped longitudinally with yellow. They are diurnal insects, 

 and, in their perfect state, feed voraciously on the foliage of the potato 

 and also on certain kinds of flowers, and in the early autumn may be 

 found on golden rod. The larvae, which undergo what is termed 'hyper- 

 metamorphosis, exist in two forms, and are parasitic in the nests of bees 

 and on the eggs of locusts (grasshoppers). They belong to the genera 

 Cantharis and Epicauta. 



Among the Meal beetles, the most abundant and pernicious spe- 

 cies is Tenebrio molitor, Linn, a plain black or very dark brown spe- 

 cies, about three-fifths inch long, rather slender and elongate, and 

 without any striking characteristics. The larvae are horny skinned, 

 slender, cylindrical worms, with well-developed feet, and are great 

 pests in warehouses and storerooms where ground grain is kept. 



