304 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
because of drought or other injury, the infestation may kill many trees 
that otherwise would have survived. Tops of larger trees may also 
be attacked and killed. 
The point of attack on living pines is usually indicated by a pitch 
tube or an exudation of pitch, but where the tree is decadent or the 
attacks are numerous, the only indication may be the extrusion of red 
boring dust or “sawdust,” which collects in the bark crevices. A later 
indication of successful attack is the fading of the foliage, which first 
becomes yellowish green and later sorrel. 
The seasonal history of the /ps beetles varies greatly according to 
the species and the climatic conditions. In northern Maine and New 
York a single generation occurs, but farther south the same species 
may pass through two or more generations in a single season. The 
species in the Southern States may complete five generations, or even 
more, per year. Under the most favorable conditions of host and 
climate a generation may be completed in less than 40 days. Other 
discussions of the Z ps beetles will be found in Swaine (407) and Black- 
man (38). 
Ordinarily these beetles can be ignored in the forest, but under cer- 
tain conditions their attacks must be guarded against. About lumber- 
ing operations the beetles breed up to immense numbers, but as each 
generation emerges it is absorbed by the new slash. Overcrowding 
in this material tends to keep down the numbers to such as can be 
accommodated in the new slash constantly being added. A sudden 
discontinuance of lumbering, however, may result in the destruction 
of advanced forest reproduction, the loss depending on the health of 
the young trees. Thus, while burning of slash is not considered nec- 
essary during active lumbering, it is advisable to clean up the debris 
when the cutting is to be discontinued. This is especially true during 
a drought period or when the residual stand is not in the best con- 
dition. The laying down of slash from thinnings and road construc- 
tion should also be avoided during drought, though under normal 
conditions there is little danger of any noteworthy injury. 
Dying trees in the forest infested with / ps may be ignored unless 
they occur in groups. Single, infested trees are nearly “always deca- 
dent or dying when attacked by the beetles and need cause no appre- 
hension. If control measures are to be undertaken against Jps beetles, 
a discussion of the methods recommended will be found on pages 47— 
51. 
Ips calligraphus is the largest species of the genus in the Eastern 
States. It is from 4 to 6.5 mm. long, ranges from reddish brown to 
black, and may be distinguished from all other eastern species 
by the presence of six teeth at each side of the diagonally truncate 
rear end. This species occurs in eastern Canada and the Eastern 
States, but in the Northern States it is not so common and is not usually 
found at the higher elevations. It breeds in the various species of 
pine in its range. It is one of the more aggressive species of 7ps and 
in the Southern States is the one first attacking trees suffering from 
drought. It breeds in the trunks of pines. JZ. grandicollis is 
smaller than J. calligraphus, ranging from 3 to 3.8 mm. long. It is 
readily recognized by the presence of five teeth at each side of its 
rear end. This species prefers the trunk of saplings or the upper 
trunk and larger limbs of more mature trees. It occurs throughout 
