24 



ON BLISTERING BEETLES. 



BY W. SAUNDERS, LONDON, ONTARIO. 



Probably there are few of our readers who are not practically acquaiuted with the 

 powerful blistering qualities of the imported Cantharides, or as the insect is more com- 

 monly, although incorrectly designated, the Spanish Fly. It belongs to the order of 

 Coleoptera (Beetles), and hence should be known as the Spanish Beetle. The use of this 

 insect, in the practice of medicine, dates from a very early period, and it is one of the few 

 remedies, the usefulness of which, within certam limits, neither time nor fashion has been 

 able to set aside. That species of Cantharides known as the Spanish Beetle is not the 

 only one in use. In China and India, allied insects, very different in colour, but similar 

 in properties, have long been used fur like purposes ; and these Asiatic insects are now 

 found in our drug markets, and having proved equally efficient with the well-known 

 European variety, are gradually growing in favour. 



It is not so well or so generally known that we have in America, and even in Canada, 

 several species of Cantharides, as well as some other closely allied bhstering insects, which 

 might at any time be used as substitutes for the Spanish Beetle (Cantharis vesicatoria). 



One of our commonest species is that known as " the Striped Blister Beetle " (Epi- 

 cauia vittata), see fig 7 in plate, which is very destructive in some seasons to the potato 

 vines, and also attacks the leaves of beets, devouring them most voraciously. At times, 

 these insects are found in such numbers, that they are very injurious to the crops they 

 infest. In some of the Western States, this species has occasionally committed havoc 

 on the potato vines as great and as terrible as that of the now well known Colorado 

 Potato Beetle. The circumstances attending their propagation and growth, as we shall 

 hereafter show, are, however, of such an exceptional character, that a year of abundance 

 is almost sure to be followed in the same locality by one of unusual scarcity. 



The Ash Grey Blister Beetle (Epicmda cinerea), is another species very common in 

 many parts of Canada. We have been informed that in the Great Manitoulin Island, 

 this species, as well as the preceding one, is usually found in considerable abundance. 

 The body is of an ash grey colour, occasioned by its being thickly clothed with short ash- 

 coloured hairs or down, which, when handled, comes oflF like the bloom of a plum, and 

 leaves the insect black. This variety attacks not only the potato leaves, but also English 

 or Windsor Beans, and according to Mr. Eiley, the foliage of the apple tree sometimes 

 suffers from its depredations. 



The Black Blister Beetle (Epicauta airata) is also common with us ; it is usually 

 found during the month of August, on the leaves and blossoms of the common Golden 

 Rod (Solid(igo). When approached or disturbed, they quickly quit their hold on the 

 plant and drop to the ground. 



These northern species are smaller in size than the European insect, a feature which 

 would add to the cost of collecting them. Another bar to their successful introduction 

 has been found in their colour. Bj' a strange misconception, the presence of the brilliant 

 green particles in the wing-cases, in the powdered Cantharides, has been associated with 

 their activity, and any sample of powder or of prepared blistering-plaster where these 

 brilliant particles are wanting, would, by many, be at once condemned. The Chinese Beetle 

 (Mylabris cichorii), recently introduced, lias done much to remove the latter objection ; 

 yet, notwithstanding, it has been shown that the Chinese insect is fully as powerful in 

 its action as that from Europe, the relative market value of the insects belonging to 

 these two species indicates that popular prejudice still favours the use of the Spanish 

 Beetle. 



