176 



BLISTER-BEETLES 



FAMILY MELOIDAE. 



( Blister-beetles ) . 



Perhaps the most interesting and economically the most im- 

 portant among" the Heteromera are the "Blister-hectics," which 

 have received this very appropriate name because they can raise 

 blisters on the human skin, caused by a substance "cantharidin" 

 found to a greater or less extent in nearly all members of this 

 family. To utilize them for this purpose they are dried and 

 pulverized, and the powder thus obtained is made into a paste, 

 which applied to the skin by physicians causes local inflamma- 

 tion and a blister. Nearly all our common species can be utilized 

 lor this purpose, bnt the kinds generally used come from Spain 

 and other European countries, hence are called "Spanish-fly," 

 (Fig. 184). 



Fig. 1S4-. — Spanish flies. After Bretatn. 



All the beetles belonging here are soft-bodied and of me- 

 dium or large size; their head is broad, vertical, abruptly nar- 

 rowed into a neck ; the pro-thorax is narrow and cylindrical, and 

 is narrower than the wing-covers, which extend well down the 

 sides ; the legs are long and slender, and the feelers are in some 

 cases knotted in the males. Many of the species are brightly 

 colored and banded, some are metallic bronze or copper, others 

 are uniformly gray, black or brown, with black longitudinal 

 stripes. All are leaf-feeders and are found in flowers. 



