cm to more than 3 cm wide and up to | m or more in length. Eggs are laid in one or 
more elongate masses along the sides of the gallery (fig. 163B). The larvae feed 
gregariously away from the gallery in the phloem. Their feeding may kill a patch of 
inner bark ranging from a few centimeters to more than 30 cm wide. Pupation 
occurs in separate cells located between the bark and wood, either in the gallery ora 
short distance forward into fresh inner bark. Adults emerge through holes chewed 
through the bark; sometimes several use the same hole. In southern latitudes and at 
lower elevations, there may be two or three generations per year. Farther north and 
at higher elevations, there may be only one generation per year or every 2 years. 
In areas where lumbering is continued for several years, the red turpentine beetle 
often becomes very abundant. The sudden discontinuance of these operations, 
therefore, may lead to attacks on healthy trees, causing catfaces and the killing of 
decadent trees in the stand. Shade tree pines in areas of new construction are also 
attacked and may be weakened or killed. Damage can be reduced or prevented by 
avoiding damage to trees or stands, deep earth fills over roots, or piling lumber of 
green logs near trees. It is also helpful to debark or spray freshly cut stumps with 
insecticide and to cut and remove pines dying from other causes. Watering or 
fertilizing individual trees also increases their resistance. 
The spruce beetle, D. rufipennis (Kirby), occurs throughout the spruce forests of 
America, and breeds in native spruces. The adult is bicolored (black with red-brown 
elytra) or uniformly black and from 4.5 to 6.2 mm long. Normally, windfalls, 
prostrate dying green trees, and overmature or weakened standing trees over 20 cm 
d.b.h. are attacked. During epidemics, however, almost all trees are attacked 
regardless of size or vigor. Attacks usually begin on the lower third of the bole 
except for the first 60 to 90 cm above the ground. Later in the season, they are 
continued upward and downward, exclusive of limbs and parts of the trunk less than 
20 cm in diameter. 
Females construct vertical, almost straight egg galleries in the phloem, engraving 
the wood. Eggs are deposited in groups along the side of the gallery. After the eggs 
are laid, the attacking adults may vacate their galleries and construct new ones in 
the same tree or in nearby trees. The larvae may feed gregariously for the first two 
instars and individually for the last three instars. Pupation occurs in cells at the end 
of larval tunnels and the winter is spent in the bark in either the larval or adult stage. 
Signs of attack are red boring dust and pitch tubes on the bark, fading and dropping 
needles, and the reddish appearance of the twigs after the needles drop. 
Several major outbreaks have occurred in eastern forests. One, from 1897 to 
1901, killed more than 5.7 million cubic meters of valuable spruce in northern New 
England and eastern Canada (59/). The underlying causes of outbreaks are not well 
understood, but piles of slash in mature stands are believed to trigger outbreaks 
(1181). Some degree of control is possible by cutting infested trees in the fall and 
removing them from the woods before spring, or by storing the logs in water. 
The eastern larch beetle, D. simplex LeConte, occurs in the Northeastern States 
south to West Virginia and west to Minnesota. It also occurs from coast to coast in 
Canada and northwestward to Alaska. Its preferred host is tamarack but it has also 
~been recorded from red spruce. Adults are dark brown, the elytra often having a 
reddish cast, and are from 3.4 to 5 mm long. 
Winter is spent as young adults or larvae in the brood galleries. Adults are active 
from May until late August. Eggs are deposited in alternate groups of three to six 
each in niches arranged along the sides of longitudinal, sinuate galleries. The larval 
mines are in the inner bark and are quite short. Adults may reemerge and construct 
349 
