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 larvae 
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 summer and 
fall, as parent adults, matured larvae, and possibly 
pupae, and as small larvae in the inner bark, but 
principally as matured larvae in the outer bark. 
ACTIVITY OF OVERWINTERED BROODS. 
North of South Carolina the overwintered par- 
Fig . 18.— The southern 
pine beetle (Dendroc- 
tonus frontalis): Adult. 
ent adults begin to extend their galleries or ? A re I U , y * n \ ar + ged ; 
° & (Author's illustration.) 
excavate new ones as soon as warm weather 
permits in the. spring (March to May) and continue their activities 
probably until 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 probably 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 until in July, or possibly as late as August. 
It is evident that the majority of the overwintered broods are out by 
