MONOGRAPH OF THE GENUS SAPERDA 41 



till into July. This would therefore prove that the pupal' stage 

 lasts three or four weeks as a general rule. The pupal chamber 

 [pi. 2, fig. 2] is invariably near the center of the smaller limbs 

 and at some distance from the surface in trunks. The top is 

 smoothly cut, and the other end is closely packed with coarse 

 fibers which are attached to the side of the gallery at one end, 

 and the portion next the pupa is packed with much finer borings 

 and then coated with very fine sawdust. This pupal chamber 

 appears to be made the previous season, but transformation to 

 the pupa does not occur, as in other species, till spring. There 

 are no records regarding oviposition habits, but this species, 

 like S. c a n.d i d a , makes a small slit in the bark and deposits 

 its eggs just underneath the surface. The young larva [pi. 10] 

 works in the inner bark and the outer sapwood for a short time 

 and before the approach of cold weather sinks its burrow to a 

 greater depth. The borings of the second year are confined 

 very largely to the interior of the wood, and during this stage 

 the limb or trunk may be honeycombed by very large, some- 

 what irregular galleries. In the latter stages of their existence, 

 the larvae not infrequently excavate broad shallow galleries in 

 the sapwood and inner bark and appear to subsist to a consider- 

 able extent on the sap collected in such cavities. This insect 

 probably requires three years to complete its transformations. 



Food plants. This borer has been recorded as destructive to 

 lombardy poplar [Emmons], cottonwood [Walsh], Populus 

 tremuloides, the common aspen [Jack], cottonwood, pop- 

 lars and willows [Lugger], is not rare on diseased Populus 

 [Hamilton], on cottonwood and other poplars [Adams], very 

 common [Provancher]. 



Description. Covered with gray hairs, diversified with patches 

 of yellow hairs on the elytra, which latter end in a sutural spine. 

 Thorax with a yellow stripe on top and sides, extending on the 

 head, which is yellow in front ; scutellum yellow ; underside gray 

 with yellow ; legs gray ; antennae gray. Sometimes the insect is 

 entirely yellowish brown (var. adspersa). 



Distribution. This species has been recorded by Leng and 

 Hamilton, from the following localities: Canada, Wisconsin, 



