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 4.3 INSECTS. Wood destroying insects require three conditions to complete their life cycle.
These are (1) a source from which the infestation can spread, (2) susceptible wood, and, (3) suitable
conditions of temperature and humidity. Insects are often selective in what they will attack. Moist
conditions that support fungal decay in wood often encourage insect infestations.
Emphasis in this section will be placed on the damage caused by insects because the damage is
usually exposed and, thus, more easily observed than the insects themselves. Furthermore, two
forms of insects, the immature and the adult form, may be involved in creating the damage. The
adult form of the insect is present for only a portion of the year. Immature forms may be observed
during other times. Thus, correct identification from the insect is often difficult. The important
characteristics for termites and carpenter ants are summarized in Table 4-2 and for wood boring in-
sects in Table 4-3.
4.3.1 Subterranean Termites. Subterranean termites refer to both native and imported
species which have specific requirements for moisture. The insects maintain their nests in the
ground or in very close contact with other sources of moisture. Subterranean termites range
throughout much of the United States (Figure 4-11).
When damaged wood is broken open, several characteristic features can be observed (Figure 4-12).
First, termites tend to eat the soft earlywood and leave behind the hard latewood. A thin outer shell
is left around the entire wood member. Some cavities may contain substantial quantities of soil
mixed with chewed wood. The gallery walls of the damaged wood and shelter tubes will have a
pale, spotted appearance resembling dried oatmeal. The appearance is produced by the plastering of
soft fecal material on the surface. There are no fecal pellets in subterranean termite galleries.
4.3.1.1 Native Species. Native subterranean termites are small to medium sized
insects that live in social groups or colonies. These individuals will be found in different stages of
metamorphosis (egg, nymph or adult) and different casts (reproductive, workers, and soldiers). Both
winged and wingless adults occur in any one colony.
A termite colony is initiated with two primary reproductives or swarmers. The swarmers are light
tan to black in color with four equal-sized wings, three pairs of legs, one pair of antennae and a pair
of large eyes on the head, and are about 1/3 to 1/2 inch long (Figure 4-13). These primary reproduc-
tives are released by a mature colony of termites during daylight hours in the spring and early sum-
mer for most parts of the country. In the desert southwest and southern California, the swarms
occur more commonly on summer nights, shortly after the first rain. Thousands of swarmers may
emerge from numerous colonies at any one time, thus allowing intermixing of individuals from
many populations. Termites are relatively weak fliers and their wings break off easily. The
presence of large numbers of wings from these swarmers is an indication that a colony is close by.
The female attracts a nearby male and the two then search for a suitable nesting site. The first eggs
are laid within a week to several weeks after mating and development of the colony is very slow for
several years.
4-19
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