Pales weevil adults are large beetles (7 to 12 mm; 0.3
to 0.5 inch long), and are dark reddish-brown with scattered patches of
long, yellow-white hairs on the wing covers (figure 1). The pitch-eating
weevil is about the same length as the pales weevil, but it is more robust
and it appears darker because the hairs on its wing covers are sparser
and shorter (figure 2). The pitch-eating weevil can also be distinguished
by its widened hind leg; that of the pales weevil is slender.
Pitch-eating weevils are similar to pales
weevils in their biology, behavior and seasonal occurrence. Adults of
both species are attracted to areas where pines have recently been cutover
or killed by bark beetles, fire, or some other agent. Here they feed nocturnally
on the inner bark of freshly cut slash and stumps. Later, after the logging
residue or dead pines dry out, the insects feed on the inner bark of small
twigs of residual pines and stems of small pine seedlings (figure 3).
Figure 3. - Pitch-eating weevils girdling loblolly pine
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This feeding on seedlings may result in small isolated
patches of bark missing near the base of the stem or may be extensive
enough to girdle the stem. Often seedlings are totally stripped of stem
bark and needles. Feeding below the root collar may occur, especially
on seedlings planted in duff or having loosely packed roots. According
to one report, pitch-eating weevils feed more extensively on the root
than above it.
The immature stages of the pales and pitch-eating weevils
are similar in appearance (figure 4). Eggs are usually laid in small niches
chewed in the bark of subterranean parts of stumps and roots. The larva
bores an irregular tunnel under the bark, scoring the wood more deeply
than the phloem. After passing through 5 to 6 larval stages, the insect
pupates in a shallow cell in the outer surface of the wood.
Figure 4. - Pine root with adult, larva, and pupae
(left to right) of pitch-eating weevil in pupal cells.
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In the South, active adult pales and pitch-eating
weevils are found all year round, usually within flying distance of any
potential pine cutting area. Adult pales weevils begin to migrate into
an area with the onset of cutting, with the probable exception of areas
harvested during the cooler months. In eastern North Carolina, egg laying,
and thus perhaps even migration, were found to cease from November to
February. Weevils probably migrate into winter cuts in the spring (figure
In eastern North Carolina, new pales weevil adults emerge
from stumps and roots 3 to 12 months after trees are cut. Emergence on
pine sites cut before June occurs from late summer to mid fall of the
same year. In pine cut in June, part of the population emerges in the
fall and part the following May and June (figure 5).
On sites cut in July or later, emergence occurs from
May through August of the following year. A similar pattern of emergence
for pitch-eating weevils, in relation to timing of cut, has been observed
in east Texas.
Since serious weevil-caused seedling damage
on the Atlantic and Gulf Coastal Plain occurs from February through May,
before new adults emerge, this damage is caused by overwintering adults
rather than new adults produced in the area. The weevils originally attracted
into areas cut after June overwinter there. During warm periods, even
in mid-winter, overwintering adults feed on pine seedlings and small pine
twigs. Subsequent feeding in summer and fall is probably increasingly
that of brood adults produced in the area.
Figure 5.-Adult migration and seasonal development of pales
weevil in the North Carolina Coastal Plain as affected by time of harvest
Cutting begins when indicated and lasts
up to 2 weeks. The black bars indicate when adults migrate into stands
cut at several different times of the year and how long they are present
in the areas. Brood development depends on the time eggs are laid, which
in turn, depends on the time of cutting. Brood from early eggs reach the
adult stage from late summer to mid-fall (open bar), while brood from
later eggs overwinter as larvae and emerge the second year (gray bar).
E indicates when egg laying begins; A indicates when brood adults begin
In areas cut before July, the brood which
emerges by fall and any surviving parent adults (black bars) will migrate
to fresh cuttings before the planting season (shaded area); therefore,
feeding damage on seedlings does not occur. In areas cut in July or after,
migrating parent adults remain in the area through the following winter
and spring, causing seedling damage.
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