LIFE-HISTORY OF BLISTER-BEETLES. 301 



Like all parasitic^^ insects that nourish on a limited amount of food and possess no 

 power to secure more, the blister-beetles vary greatly in individual size in the same 

 species, and the larvae have the power of accommodating their life to circumstances, 

 and of assuming the coarctate larval form earlier or later according to the size of the 

 egg-mass which they infest. I have had some interesting illustrations of this in my 

 experiments with them. In an average sized egg-pod of the Differential Locust, how- 

 ever, there are more than enough eggs to nourish the largest specimen of E. vittata, and 

 a few are usually left untouched. 



The period of growth, from the first feeding to the coarctate larva, averages, as will 

 be gathered from the foregoing, about a month ; yet in the month of September, out- 

 doors, uuder screens where I have had the Differential Locust oviposit for the experi- 

 ment, I have known the full larval growth of vittata to occupy but 24 days. As this 

 species occurs in the beetle state as early as Juno in the latitude of Saint Louis and as 

 late as October, there are possibly two annual generations here and farther south. 



LARVAL HABITS OF MACROBASIS AND HEXOUS. 



The characteristics of the triungulins of the blister-beetles, represented by Epicauta 

 and Henous, are remarkably similar, and point to unity of habit.^^ The same holds true 

 of the characters of the second, coarctate, and third larva, and of the pupa of Epicauta 

 and Macrobasis. They are precisely alike; so that, while appreciable differences may 

 be found in the triungulins, it is doubtful whether the subsequent developmental 

 stages will indicate specific or even generic differences in speciesof similar size in these 

 three genera. 



That the eggs of Ejncauta may exceptionally hibernate is possible, but, from their 

 delicate nature, improbable. That the triungulins frequently do so there caa be no 

 doubt, especially in species like the Black Blister-beetle, which is found on the flowers 

 of Solidago, Eupatorium, &c., till the end of October, and continues laying till fro -t. 

 I have, at the present time (November 5), many of these last that are quietly huddled 

 together, and, with winter temperature, will doubtless remain so ; while others have 

 worked in between the locust-eggs, there evidently to remain without feeding till 

 spring opens. I have also found as many as five triungulins of this species curled up 

 in the deep red mucous matter that surrounds the eggs of (Edipoda jjhana^coptcra, all 

 numb and torpid, and evidently hibernating. 



RESUME. 



From the foregoing history of our commoner blister-beetles, it is clear that while 

 they pass through the curious hypermetamorphoses so characteristic of the family, 

 and have many other features in common, yet Epicauta and Macrobasis differ in many 

 important respects from Meloe and Sitaris, the only genera hitherto fully known bio- 

 logically. To resume what is known of the larval habits of the family, we have : 



1st. The small, smooth, unarmed, tapering triungulin of the prolific AS'i/a?'is, with the 

 thoracic joints subequal, with strong articulating tarsal claws on the stout-thighed 

 but spineless legs, and, in addition, a caudal spinning apparatus. The mandibles 

 scarcely extend beyond the labrum ; the creature seeks the light, and is admirably 

 adapted to adhering to bees but not to burrowing in the ground. The second larva 

 is mellivorous, and the transformations from the coarctate larval stage all take placs 

 within the unrent larval skin. We have — 



2d. The more spinous and larger triungulin of the still more prolific Meloe, with long 

 caudal setae, but otherwise closely resembling that of Sitaris in the femoral, tarsal, 

 and trophial characters, in the subequal thoracic joints, in the unarmed tibiae, and in 

 the instinctive love of light and fondness for fastening to bees. The second larva is 

 also mellivorous, but the later transformations take place in the rent and partly shed 

 skins of the second and coarctate larvae. We have — 



^An iusect is not properly parasitic tliat simply feeds on eggs, but tlie terra is permissible and even 

 necessary to characterize aiid distinguish those species which davelop within and are confined to a 

 locust egg pod from the predaceous species that are not confined but pass from one po4 to another, 



^'The slight differences between some of the species are pointed out in tbe original descriptions. 



