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pollinators, and the importance of the honey-producing honeybee 
is too well-known for discussion. The only destructive members of 
the family are the carpenter bees, several species of which attack 
and damage wood in use. 
The carpenter bee, Xylocopa virginica virginica (=virginica) 
(Linnaeus), is an important pest because of its habit of tunneling 
into the solid wood of beams, rafters, telephone poles, or struc- 
tural timbers. This may lead to structural damage, especially 
when the same piece of timber is attacked for several years. Dead 
but sound wood of cypress, cedar, white and hard pines, and Cali- 
fornia redwood that has been softened by weathering, seems to be 
preferred. The adult, which is about 25 mm. long, bores a hole 
about 9 mm. in diameter straight into the wood for a short dis- 
tance, then makes a right angle turn and follows the grain of the 
wood for a distance of 6 to 8 inches. Sometimes two bees use a 
common entrance hole. When this happens the tunnel is extended 
in opposite directions from the entrance hole. Eggs are deposited 
singly in separate chambers in the tunnel, each of which is largely 
provisioned with pollen. Each larva lives and feeds in its chamber 
until mature. Adults feed on pollen during daylight hours. Fe- 
males spend the night in their burrows, and males, under boards 
or in other protected places. Winter is spent as young adults in 
their tunnels. There is one generation per year. 
Living bees in tunnels can be killed by running a stiff wire all 
the way to the end of the tunnel. 
Two other species of carpenter bees, Xylocopa virginica texana 
Cresson and X. micans Lepeletier, also occur in eastern United 
States. The former is found from Maine to Michigan and south to 
Florida and the Gulf of Mexico. The latter occurs from North 
Carolina to Florida and westward along the Gulf Coast. 
INSECTS AND TREE DISEASES 
Insects are involved in or are directly responsible for the trans- 
mission of many serious diseases of forest and shade trees in 
eastern United States. Some of these diseases, such as Dutch elm 
disease and elm phloem necrosis, are among the most destructive 
tree diseases known. The majority are caused by various species 
of fungi. One is of virus origin. A few, such as Dutch elm disease 
and elm phloem necrosis, attack living, healthy trees and kill 
them quickly. Many stain the sapwood of coniferous trees, usually 
of felled timber. They also occur occasionally in living trees 
weakened by environmental conditions and hasten their death. 
Others cause the decay of sapwood or heartwood of dead, dying, 
and felled conifers. 
Fungus diseases are transmited by insects through the direct 
transfer of spores from infected to healthy trees or wood. The 
bodies of insects emerging from diseased material become con- 
taminated with the spores and when the insect attacks healthy 
material spores are rubbed into the wounds. Wind-borne spores 
also gain entry into healthy trees through insect-produced wounds. 
Viruses, such as the one responsible for elm phloem necrosis, are 
most often transmitted by species of sucking insects. 
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