INSECT ENEMIES OF EASTERN FORESTS 319 
have dropped. Often the needles fall while still green, and the tree 
may be nearly bare of foliage within a few weeks after attack. The 
reddish appearance of its twigs is characteristic of such recently in- 
fested trees. Woodpecker work is often conspicuous and serves to 
draw attention to trees still infested. 
The eastern spruce beetle is one of the most serious bark-beetle 
enemies of trees in the East. Several outbreaks took place in the last 
century, but the first to be studied occurred in eastern Canada and 
northern New England in 1897-1901, causing a loss estimated by 
Hopkins (234) at more than a billion feet of fine spruce. After this 
outbreak the beetle appeared to be very rare until about 1915, but in 
the next few years extensive outbreaks took place in Quebec and 
Ontario, and lesser infestations in New Brunswick and Newfoundland, 
and as far west as Manitoba. In 1936 and 1987 serious infestations 
existed in the Green Mountain National Forest in Vermont and less 
serious ones in other parts of New England and northern New York. 
No infestation of the eastern spruce beetle has been investigated with 
sufficient thoroughness to reveal the underlying factors that cause it to 
reach outbreak proportions. It is well known, however, that severe 
damages occur only in spruce stands containing a considerable propor- 
tion of mature or overmature spruce. Swaine’s (j02) work has indi- 
cated that piles of slash responsible for an unusual increase in beetle 
populations in a mature spruce forest may produce a serious outbreak, 
It is possible that climatic factors are very important in building up 
such infestations (Nash 3/6), 
Control of bark beetles under forest conditions is discussed on 
pages 47-51. 
The eastern larch beetle (Yendroctonus simplex) is dark red- 
dish brown, 3.5 to 5 mm. long, with the front of the head convex 
and the epistomal process with the sides subparallel and reaching 
but not extending beyond the epistomal margin. This species is found 
throughout eastern Canada and the eastern part of the United States 
from the Atlantic coast westward to Minnesota and Manitoba and 
southward to New York, and with a southern extension through the 
mountains of Pennsylvania to northern West Virginia. Its host is 
the eastern larch or tamarack (Larix laricina (Du Roi) (Koch.) 
(Simpson, 380) ). . 
The galleries of Dendroctonus simplex are longitudinal, wavy or 
winding, often branched, and sometimes anastomosing. The eggs are 
deposited in niches, often arranged in alternate groups in the sides of 
the egg galleries. The larval mines are in the inner bark and are 
usually quite short (Hopkins, 254). This beetle breeds in dying, 
felled, and injured but living, eastern larch. It is not particularly 
ageressive, and living trees killed by it have usually been weakened 
through defoliation by the larch sawfly or from other causes. Control 
work is seldom necessary, but when it is justifiable it can be readily 
accomplished by barking infested trees, or by bark-penetrating sprays, 
pages 49-51. 
The red turpentine beetle (Dendroctonus valens) is the largest 
species of the genus and is usually from 7 to 8 mm. long. Its color 
ranges from light reddish brown to dark brown, but the reddish color is 
more characteristic. It readily attacks all species of pine and per- 
792440°—49 21 
