CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 325 



and flexible wing-covers, and by a rounded head joined to a small 

 thorax by a slender neck. The adults are leaf-feeders, and are gre- 

 garious. As larvae they feed on the egg-masses of grasshoppers and 

 are, therefore, beneficial. Each female lays 500-600 eggs in a cavity 

 in the soil in late summer and the eggs hatch in about 10 days. The 

 larva on hatching from the eggs is long-legged, large-headed and active 

 (the triungulin stage); and on moulting it assumes the second stage 

 (carabidoid) with short legs and relatively smaller head. After 

 another moult it assumes the third stage (scarabaeidoid), and with 

 the fourth moult is formed the coarctate larval stage (winter stage). 

 In the spring another moult occurs before the pupal stage is entered. 

 On account of their habit of traveling sometimes like army- worms blis- 

 ter beetles are often called "army beetles." Seven species of Blister 

 Beetles of economic importance are found in Canada and the Northern 

 States. 



1. Black Blister Beetle (Epicauia pennsylvanica DeG.). — Uni- 

 formly black and ^^ inch long; one of the "Aster Bugs" of the florists; 

 serious pest of garden vegetables and flowers; occurs from June to 

 October. 



2. Grey Blister Beetle (Epicauta cinerea Forst.). — Uniformly grey; 

 \^ inch long; a pest of beans, potatoes, vetch and alfalfa; occurs in 

 July and August. 



3. Striped Blister Beetle {Epicauta vittata Fab.). — One-third inch 

 long, with four black stripes on back; the "old-fashioned potato-bug;" 

 a general feeder; occurs from June to September; eggs laid on plants 

 or upon the ground. 



4. Margined Blister Beetle {Epicauta marginata Fab.).^Of a gen- 

 eral black color except that the wing-covers are margined with grey; 

 a general feeder; occurs from July to October. 



5. Ash-grey Blister Beetle {Macrohasis unicolor Kby.). — Uniformly 

 ash-grey; feeds on beets, potato and legumes; occurs in June and July. 



6. Spotted Blister Beetle {Epicauta maculata Say).— With a black 

 body which, excepting small areas on the wing-covers, is covered with 

 grey hairs. Attacks beets, cabbage, spinach, beans and clover in the 

 Western provinces. 



7. Western Blister Beetle {Cantharis mittalli Say). — Three-fourth 

 to one inch long; head, thorax and body metallic golden green; wing- 



