348 NATURAL HISTORY OF ARTHROPODS. 



this pseudo-pupa. In this jjseudo-pui^al state liibeniation takes place, and the next 

 spring the pseudo-pupa bursts open, and the third larva appears. This larva, which 

 otherwise closely resembles the scarabajidoid form before mentioned, has rudimentary 

 mouth-parts and poorly developed, two-jointed feet. After about two weeks, during 

 which time this third larva does not leave the cavity in which it emerged from the 

 pseudo-pupa, it changes into a normally formed beetle-pupa, and in about twenty days 

 more the beetle appears. 



Epicauta cinerea, E. pensyloanica, and Macrohasis unicolor eat potato-leaves as 

 imagos, but as larvae they are useful to man by destroying locusts. The Rocky Mountain 

 locust lays its egg-masses just beneath the surface of the ground, and these species of 

 Epicauta oviposit near the locust eggs, in a hole which the female E/picauta digs for the 

 purpose, afterwards covering her eggs by scratching dirt over them with her feet. The 

 eggs hatch in about ten days, and the light brown triungulins, if the 

 weather is warm, soon begin searching out locust eggs for food ; if it is 

 cold weather they remain closely huddled together until warmth induces 

 activity. Dr. C. T. Riley observes : " Should two or more triungulins 

 enter the same egg-pod, a deadly conflict sooner or later ensues until 

 one alone remains the victorious possessor." After devouring about 

 two eggs, that is, at the end of about eight days after beginning to 

 feed, a moult takes place, and the second larval form appears, the foi-m 

 ^mufa^cin^ft' designated as carabidoid. The carabidoid form lasts about a week, the 

 succeeding scarabseidoid form about a week ; after reaching the ultimate 

 stage of the second larva, it feeds about a week, then leases the remnants of the 

 locust's egg-mass, and rounds out for itself a smooth cavity in the ground. After 

 being in this cavity about four days, a moult takes place, but the skin is not entirely 

 shed. The soft skin quickly hardens, and the insect is now a pseudo-pui^a. After 

 hibernating as pseudo-pupa, the skin again bursts, and the third larva appears. This 

 third larva burrows about in the ground, and in a few days the true pupa is formed, 

 from which, in fi-\-e or six days, the imago appears. The functional significance of the 

 third larva, wliich, in these insects as in Lytta vesicatoria, eats nothing, is not yet 

 understood. 



The genus Mylabris includes over two hundred and fifty beetles in which the 

 elytra cover the entire abdomen, the mandibles are short, the antennaj are gradually 

 enlarged toward the apex. The species are often black or blue-black, banded with yellow, 

 and of considerable size. N"o true Mylabris is found in the United States. Cordylos- 

 pastafuUeri from N^evada, with eight-jointed antennae, is an allied form to Mylabris. 



Sitaris differs from Mylabris in having wings partly exj)osed, and the rudimentary 

 elytra narrowed rapidly behind, and not reaching the tip of the abdomen. The 

 first to describe all the different stages of any species of Meloidse was J. H. Fabre, 

 who, in 1857, published his account of the metamorphoses of Sitaris humeralis, a 

 French species, which is parasitic on bees of the genera Anthophora and JBombus. 

 Fabre's account of the life history of tS. humeralis is briefly given as follows : The 

 males and females, as soon as they have emerged from the pupae, pair in the subter- 

 ranean nests of the bees upon which they are parasitic, and the female lays soon 

 after about two thousand eggs, near the entrance of the nest. The triungulins, which 

 hatch in about a month, hibernate, without feeding, among their egg-shells, and the 

 next spring attach themselves to the hairs upon the thorax of the male bees, from 

 which they probably pass over to the females during the pairing of the bees. Thus 



