THE GENUS DENDROCTONUS. 57 



tured and but slightly narrowed toward the head; the elytra have 

 moderately coarse rugosities between indistinct rows of punctures, 

 and the declivity is convex, with a few long hairs. (See fig. 18.) It 

 attacks healthy, injured, and felled trees of all of the pines and spruces, 

 from southern Pennsylvania southward into Florida and westward 

 into eastern Texas and Arkansas. It excavates long, winding egg 

 galleries (fig. 19) through the inner bark, and marks, but does not 

 groove, the surface of the wood (fig. 24). The whitish, legless larvic 

 excavate short, broad larval mines at more or less regular intervals 

 at right angles along the sides of the egg galleries, usually, but not 

 always, exposed in the inner bark. The transformation to pupae 

 and adults takes place in the outer corky bark. The presence of 

 this species is indicated by pitch tubes on the main trunk of living 

 trees, and by the fading and yellowish to red foliage as the trees die 

 from its attack. It is a very destructive enemy 

 of southern and southeastern pines. 



SEASONAL HISTORY. 



Northern Section. 



overwintering stages. 



The broods pass the winter in the outer bark of 

 trees attacked during the preceding suramer and 

 fall, as parent adults, matured larvae, and possibly 

 pupse, and as small larvte in the inner bark, but 

 principally as matured larvae in the outer bark. 



ACTIVITY OP OVERWINTERED BROODS. FiG. 18.— The SOUt h em 



pine beetle {DgucIwc- 



North of South Carolina the overwintered par- tonui frontalis): Adult. 

 ent adults begin to extend their galleries or f/^^'i^ t^V''^?'"^; 



o ° (Autlior*s illustration.) 



excavate new ones as soon as warm weather 

 permits in the spring (March to May) and continue their activities 

 probably imtil toward the middle of May or later. The overwin- 

 tered broods of young adults begin to emerge about the first of May. 

 The first swarming period occurs about the middle of May, but strag- 

 glers continue to come out probablj- as late as the middle of June or 

 July. This relates especially to its northern range and to the higher 

 altitudes. The overwintered broods of matured larvae begin to trans- 

 form to pupae and adults in March and April, but the principal trans- 

 formation is in April, so that the adults are ready to emerge with the 

 overwintered broods of young adults. Some of the broods of over- 

 wintered young larvae probably develop in time to emerge with the 

 swarm, but some of them are generally retarded and do not com- 

 plete their development imtil in July, or possibly as late as August. 

 It is evident that the majority of the overwintered broods are out by 



