60 THE SCOLYTID BEETLES. 
FIFTH GENERATION. 
There may be a partial or beginning of a fifth generation, especially 
at the lower elevations and more southern localities of the northern 
section, the individuals of which pass the winter as parent adults 
and young larvae. 
It is evident that in the northern section of the range of this spe- 
cies there are from two to three complete seasonal generations dur- 
ing the period from about the first of May until activity ceases in 
the fall, or at any rate all of the broods of at least two generations 
develop and emerge during the period of activity within the range 
including the higher elevations of North Carolina and lower eleva- 
tions at the northern limit, and that all of the broods of at least 
three generations develop and emerge at the medium and lower ele- 
vations south of Virginia, represented by a central locality included 
in a range of, say, 1,000 feet above and 500 feet below Try on, N. C, 
while portions of the fourth and all of the fifth generation overwinter. 
PERIODS OF DESTRUCTIVE ATTACK. 
In the area including the mountains of North Carolina and north- 
ward there is one principal period of destructive attack, viz, during 
August and September, and in the area represented by Tryon, N. C, 
there are two principal periods of destructive attack, one from the 
middle of July to the last of August, the other during September and 
October. 
Southern Section. 
In the southern section, including the Atlantic or Gulf region of 
loblolly and longleaf pines, there is a complex overlapping of prob- 
ably five or six generations, most difficult to define on account of 
the almost continuous activity during the year, but of course more 
or less retarded during the colder weather of the winter months. It 
would appear, however, that the principal periods of destructive 
attack are similar to those of the Tryon section. 
HABITS. 
The adult beetles enter the living bark, usually on the upper por- 
tion of the main trunk of standing healthy or injured trees or on the 
entire trunk of newly felled ones, and excavate long, sublongitudinal, 
winding egg galleries (figs. 19-22) through the inner bark. Eggs are 
placed in little niches along the sides of these galleries at more or 
less regular intervals of one-half inch or more. 
The freshly hatched larvas, which are short, stout, whitish grubs 
with a faint frontal elevation in the middle of the head and with 
the opposite end of the body blunt or truncate, excavate their larval 
mines at right angles to the egg gallery (fig. 19), and usually exposed 
