FIELD BOOK OF INSECTS. 



fine, gray pubescence. Its larvae make galls in poplar 

 and willow stems. The male discoidea also has unmarked 

 elytra; they are dark; there are light grayish lines on the 

 pronotum and the underside is silvery; legs reddish. 

 The female is yellow on the head, pronotum, scutellum, a 

 crescentic bar in the middle of each elytron, and a spot in 

 front and behind each of these. It breeds in hickory and 

 butternut. 



S. vestita, the Linden-borer, is olive-yellow but each 

 elytron has three small, black dots. Large specimens are 

 an inch long. 



Our largest species is calcarata, the Poplar- and Cotton- 

 wood-borer. It is usually at least an inch long; dense, 

 gray pubescence, with the front of the head, three stripes 

 on the pronotum, the scutellum, and numerous lines and 

 blotches on the elytra, orange-yellow. 



5. obliqua (reddish, with lighter, oblique markings on 

 the elytra, which are spined at the tip; .6 to .8 in. long) 

 and mutica (black, with light markings; elytra not spined; 

 .4 to .6 in. long) have distinct color-rings on their antennae. 

 The former breeds in alder; the latter, more western, in 

 willow. 



S. cretata is a fairly common apple-borer, especially 

 in the Middle West. It is brow r n, with two large, white 

 spots on each elytron and white stripes on the sides of the 

 pronotum; length, .5 to .8 in. S. fayi is rarely .5 in. long; 

 darker and more slender than cretata; the elytral spots 

 narrow, and near the suture, and an additional small spot 

 at the base. Both make gall-like swellings in stems of 

 CratcEgus. 



S. tridentata, the Elm-borer, is grayish -black; there 

 is an orange stripe on each side of the pronotum; each 

 elytron has a narrow orange stripe near the margin and 

 three bands, of which the last two are quite oblique and 

 usually meet the corresponding ones on the opposite side; 

 the front of head is very flat; .4 to .6 in. long. S. imitans 

 resembles it but the elytra are rounded at their apices, 

 instead of being somewhat truncate; the elytral markings 

 are narrower, yellow r er, and the hind band is not distinctly 

 oblique. 



360 



