ence of distinct pitch tubes, fine reddish boring dust, or white 
resinous boring particles on the bark. The female is joined in the 
chamber by a male and after mating she begins construction of a 
gallery diagonally across the grain of the wood, etching the sur- 
face of the wood faintly. The direction of the gallery eventually 
is reversed thus creating a typical S-shaped or serpentine pattern 
(fig. 87B). Eggs are deposited at intervals of one-eighth to one or 
more inches in niches in each side of the gallery, one egg per 
niche. Hatching occurs in 3 to 9 days, and the larvae tunnel away 
at right angles to the gallery. Young larvae produce thread-like 
mines. They are visible when the inner bark is exposed. As the 
larvae develop, their mines become larger and are usually con- 
cealed in the inner bark. As the larva approaches maturity, it 
constructs a cell in the middle bark in which to pupate. Each 
adult bores its own emergence hole. All of the adults in a given 
brood may emerge during a period of 10 to 32 days. Three to five 
generations per year have been recorded in western North Caro- 
lina. In Virginia and West Virginia four and a partial fifth gen- 
erations occur. In the Deep South there probably are five per 
year. 
Newly-emerged beetles may attack immediately adjacent trees 
or they may fly to stands some distances away. Trees under 15 
years of age and less than 2 inches in diameter are rarely at- 
tacked. When outbreaks are developing, scattered groups of pines 
in young dense stands are attacked. Once an epidemic is under- 
way, stands of all age classes and densities are vulnerable. Spot 
infestations, which may be anywhere from one-eighth to several 
hundred acres in size, are characterized by a central zone of de- 
foliated trees, a surrounding zone of red-topped trees, and a per- 
iphery of infested trees with green or fading crowns. The needles 
of pines infested during mid-summer turn yellow in 2 or 3 weeks 
and reddish-brown in 4 to 6 weeks. Death results either from the 
girdling of the main stem or from the effects of the blue stain 
fungus, Ceratocystis minor, which the beetles introduce into the 
tree. 
Southern pine beetle outbreaks appear to be caused by condi- 
tions that favor an increase in the vigor and size of beetle popu- 
lations but which, at the same time, reduce the vigor of host trees. 
Drought, overstocked stands, stand disturbances, and a reduction 
in the abundance and effectiveness of natural enemies are prob- 
ably responsible at times. In some parts of the region, especially 
at high elevations and in the northern parts of the insect’s range, 
low winter temperatures are often highly effective in terminating 
outbreaks (39). A return to normal in conditions affecting the 
size and vigor of populations as well as the vigor of trees also 
appear to be helpful in the control of outbreaks. 
Management practices designed to improve and maintain the 
vigor of stands, and the removal of high-risk trees, such as those 
struck by lightning or those attacked and weakened by other in- 
sects, are helpful in preventing outbreaks. Once an outbreak is 
underway, the salvage or chemical treatment of infested trees is 
also helpful in suppressing populations. To be effective, these 
practices must be applied before the beetles emerge from the 
trees. 
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