270 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



The pupa is formed with the ventral aspect uppermost, and 

 the adult remains on its back for about 4 hours after it has 

 emerged. The beetle is of course very soft, and remains in the 

 pupal cell, until it is fully hardened and colored, which requires 

 about 24 hours.' 



The coloration of the adult. The beetle which has just 

 emerged is quite as yellow as was the pupa. The eyes, antennae, 

 and mandibles (sometimes also the labrum) are black, the elytra 

 are grayish orange, and the wings gray. The insect becomes 

 colored gradually, but it is some 20 hours before the character- 

 istic coloration is reached. The beetle is entirely blackish above 

 within 5 hours, and the underparts do not begin to color up at 

 all until after that time. The centers of coloration are the prono- 

 tum, the ventral aspect of the pygidium, the bases of the elytra, 

 the bases of the coxae, and the femoro-tibial joints of the legs. 



THE RANGE OF FOOD PLANTS. 



In nature, the alder flea-beetle is confined almost entirely 

 to the leaves of the alder, at least in Maine, and the only other 

 plant on which the writer has taken them is the willow (Salix 

 rostrata Richards.) 



There is a biological race of this species which occurs on 

 balsam poplar, in Veazie, Maine. Eggs, larvae, pupae, and adults 

 are indistinguishable from the typical bimaryinata, and the larvae 

 and adults eat alder or willow as readily as they do balsam pop- 

 lar. The forms taken on alder however (both larvae and adults) 

 have been tested many times on the leaves of the balsam poplar, 

 but the results have always been negative. This is not surpris- 

 ing, when individuals which had already eaten alder were con- 

 cerned, for the glandular leaves of the balsam poplar have a 

 very decided taste and smell, but just hatched larvae of the alder 

 race which had never tasted any food were equally emphatic 

 in their refusal to subsist on the balsam poplar. Both larvae 

 and adults will feed freely on the leaves of willow; they ate 

 the foliage of all species with which they were tested. 



Nevertheless the writer feels very sure that these are only 

 biological races of the same species, if they deserve even that 

 distinction. The habits, size, appearance, and life-history of 

 the variety on the balsam poplar are exactly the same as that 

 described for the alder forms, save that the eggs are deposited 



