316 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
which was in 1945-47, in the northern part of its range. The known 
hosts, according to Hopkins, include Pinus strobus es P. taeda L.. 
P. rigida Miller, P. virginiana Miller, P. pungens Lambert, P. echi- 
nata Miller, P. glabra Walter, P. palustris Miller, Picea rubra Link., 
and Picea excelsa (?) 
Often the first indication of the presence of the beetle in a forest 
is the appearance of groups of dying or dead pines whose death cannot 
be explained as the result of fire or other destructive agencies. Usually 
such trees show pitch tubes on the surface of the bark of the middle 
and upper trunk. If such trees are examined by removing some of 
the bark im this region, it will be found that the inner bark, next to 
the wood, is riddled by characteristic winding or S-shaped galleries 
(fig. 62). These are the egg galleries made by the adult beetles. In 
recent infestations small brownish or black beetles one-eighth of an 
inch long will be seen in these burrows (fig. 63). At the sides of the 
ego gallery the beetle gouges out small niches and in each places a 
small pearly white egg. The larvae hatching from these eggs bore 
through the living phloem and after extending ‘their mines only : a short 
distance attain full larval erowth. Each larva then carries its bur- 
row outward into the bark and makes an enlarged oval chamber in 
which it passes into the quiescent pupal stage and later transforms to 
the adult. 
The development is unusually rapid, as under favorable conditions 
a brood can develop from egg to adult in 30 to 40 days. From 3 to 
FIGURE 62.—Winding galleries made by adults of the southern pine beetle (Den- 
droctonus frontalis). (The larger ones are those of the southern pine sawyer 
(Wonochamus titillator), which often destroys many broods of the former.) 
Slightly reduced. 
