1912 ENTOMOLOGICAL SOCIETY. 83 



BLISTER BEETLES. 



Arthur Gibson, Chief Assistant Entomologist, Central Experimental 



Farm, Ottawa. 



In the Family Meloidfe there are several beetles, known popularly as Blister 

 Beetles, some of which almost every year in Canada cause considerable anxiety to 

 farmers and gardeners, from their habit of appearing suddenly and often much 

 reducing the crop which they happen to attack. These blister heetles differ much 

 in size and appearance, but all are soft-bodied insects, and in shape slender and 

 cylindrical. Being gregarious in habit, they congregate in great numbers, and 

 when they appear suddenly and attack a crop, the plants are often entirely ruined 

 in two or three days. Fortunately, however, they oftentimes disappear from a 

 locality as suddenly as they came. 



As is well-kno^v^^, blister beetles derived their popular name from their 

 possessing powerful vesicating properties. Many cantharidis have this property, 

 but the species which has been used most extensively in medicine is the .Spanish 

 Beetle (Cantharis vesicatoria) . Our common North American species, the Striped 

 Blister Beetle (Epicaiita vitlata) has been found to be fully equal to the Spanish 

 Beetle as a vesicant. 



In their life-history, blister beetles differ remarkably from other coleoptera- 

 Chittenden, in the United States Department of Agriculture Year Book, 1898, 

 states: 



" Tlie blister beetle eggs are laid on plants or upon the ground. From each 

 hatches a small long-legged larva, called a ' triungulin,' which runs actively about 

 in search of a grasshopper egg-pod, which it enters and feeds upon. After a time 

 it casts its skin and assumes what is called the ' carabidoid ' larval stage, and when 

 it next moults it resembles a white grub, ' the scarabjeidoid ' larval stage. When a 

 larva has finished its quota of locusts' eggs, it undergoes a third moult and forms 

 within its own skin what is known as the ' coarctate ' larval stage or ' pseudopupa,' 

 and in this condition usually passes the winter. In the spring the fourth and 

 ultimate larval moult takes place, and with the fifth moult the insect enters upon 

 the true pupal stage, and in due time transforms to a beetle." 



The Black Blister Beetle {Epicauta pennsylvanica, DeG.) (Fig. 1, on plate). 

 This species is the one which, in Canada, has been most complained of. It occurs 

 particularly in Ontario and the Eastern Provinces, but instances are on record of its 

 appearing in destructive numbers in Manitoba, Saskatchewan and British Columbia. 

 In colour, as its popular name implies, it is uniformly dull black, and in length 

 varies from a little more than a quarter to slightly more than half an inch. This 

 beetle has a very wide range of food plants. It is particularly destructive to the 

 potato, and is mostly complained of as a pest of that plant. Mangels, beets, car- 

 rots, cabbages, tomatoes, corn and Windsor lieans are also freely attacked, and even 

 such plants as mustard, asters, clematis, zinnia and other garden plants. Prof. 

 E. W. Claypole has recorded the species as "devouring the flowers of the Great 

 Rag-weed {Ambroda trifida)." The species commonly occurs in August on the 

 leaves and blossoms of golden rod and thoroughwort, and has also been found on 

 amaranth and ironweed. At Ottawa, we have found the beetles defoliating clema- 



