204 



NATURAL HISTORY. 



This ortran is formed, like the proboscis of butterflies, by the union of the 

 two maxillae, each of which is hollowed out like a trough on its inner 



surface, and the two being pressed to- 

 gether thus form a tube which is used 

 in sucking the nectar of flowers. 



One of the best-known members of 

 the present group is the blistering-beetle, 

 or Spanish fly, which has an extensive 

 use in medicine. It is a bronze-green 

 beetle (it is not a fly at all) about three- 

 quarters of an inch in length, and it has 

 its home in southern Europe and the 

 adjacent parts of Asia. Its vescicatory 

 powers are due to a substance known as cantharidin which occurs in 

 all parts of the beetle. It is not confined to this species alone, but in 

 most of the allied forms, some containing an even greater proportion 

 than the officinal Spanish flies. The preparation of the flies for the 

 market is a simple affair ; they are killed by heat and then dried. For 

 producing a blister they are ground, and the powder is made into a plaster. 



Fig. 197. — Palm-boring weevil. 



Fig. 198. — Spanish flies (Lytta vescicatoria) . 



Spanish flies have been extensively used in medicine for many years, 

 and yet the life-history was not w r orked out until 1879. Like many of its 

 allies it lives a parasitic life during its larval state upon a hymenopterous 

 insect, and this habit has introduced a complex metamorphosis into its 

 development. 



The position of Stylops and its allies, another group of bee-parasites, is 

 very uncertain ; there is reason for believing that it is not a beetle at all, 

 and yet from its habits it may be considered here. There is a great differ- 

 ence between the sexes, as is shown in our figures. The male has very 

 large wings, capable of being folded up like a fan, but the w r ing-covers 

 are little crumpled things, of no functional importance. The females, 



