346 NATURAL HISTORY OF ARTHROPODS. 



pure cnntliaridin for use in preparing medicines. Pure cantharidin (C 5 H 6 O 2 ) is insolu- 

 ble in water, sparingly soluble in alcohol, and readily soluble in ether ; with the latter 

 fluid it can be extracted from cantharides, and then purified by separation from the 

 accompanying oils and by crystallization. Cantharidin crystallizes in colorless, four- 

 sided prisms or lamina?. Although Lytta vesicatoria (the so-called Spanish fly) is the 

 species generally used in medicine, other Meloidae among which may be mentioned 

 species of Mylabris, Epicauta, and Macrobasis have been used, and give a larger 

 percentage of cantharidin than is obtained from Lytta vesicatoria. Probably all 

 species of Meloidae are vesicant to a greater or less degree. In preparing Spanish 

 flies for the market, they are killed by heat, and then rapidly dried. The extent to 

 which these insects were used in early times is indicated by the eighty-five citations, 

 given by Jordens in 1801, of works in which considerable mention of 

 cantharides is made. 



Species of Meloidae are injurious as well as useful ; a number of 

 species devour potato-leaves, both in this and in other countries. In 

 Italy Lytta erythrocephala sometimes devastates potato-fields ; in this 

 country Epicauta cinerea, E. pensylvanica, E. vittata, and J\Iacrobasis 

 unicolor attack potatoes in addition to other plants. E. vittata and 

 FIG. 388. Epi- M. unicolor are, however, known to prey at times upon the larva? of 



cauta vittata. 



the Colorado potato-beetle. 



The mode by which the Meloidae develop from the egg to the imago lias been 

 termed hypermetamorphosis. In brief, it is as follows : The egg, which is laid in the 

 ground, hatches into an active larva, called the triungulin, from the name triungulinus 

 given to it by Dufour in 1828. These triuugulins, or first larvae, run actively about; 

 some of them ascend plants, others live in sand, their mode of life varying according 

 to what their subsequent history will be. The triuugulins which climb plants, as do 

 those of Meloe, remain about the flowers, attaching themselves to flies, bees, and wasps 

 that visit the flowers for honey, and were described by several early naturalists as bee- 

 lice. The triungulins of Meloe are sometimes so abundant, according to Dr. C. V. 

 Riley, on hive-bees, as to worry them to death, although he believes these triungulins 

 " cannot well, in the nature of the case, breed in the cells of any social bee whose 

 young are fed by nurses in open cells." Those triungulins that attach themselves 

 to such wild bees and wasps as are fitted to further their development are carried by 

 these Hymenoptera to their nests, wherein they go from the bee to its egg in a cell, 

 and devour the egg, after which a moult takes place, and the triungulin, formerly so 

 active, is converted into a clumsy second larva, which feeds upon the honey provided 

 for the young hymenopteron. The second larva then partially moults, remaining, how- 

 ever, within its skin, and becomes a pseudo-pupa. A third larva follows by similar 

 partial moulting of the pseudo-pupal skin, and finally a true pupa and imago. Certain 

 triungulins, or first larva?, which wander about the ground, as do those of Epicauta 

 and Macrobasis, have been found by Dr. C. V. Riley to feed upon the eggs of the 

 Rocky Mountain locusts ( Caloptenus spretus) and upon eggs of C. differentialis. The 

 triungulin which devours locust eggs moults to enter what Dr. Riley has called, on 

 account of its resemblance to larvae of Carabidae, the "carabidoid stage of the second 

 larvae ;" another moult transforms it to what the before-mentioned author has termed, 

 because of resemblance to larvae of Searabaeidae, the " scarabaeidoid stage of the 

 second larva ; " still another moult produces what, following Dr. Riley's nomenclature, 

 is the " ultimate stage of the second larva." Leaving now, for the first time, the 



