Lyctids are commonly known as (true) powderpost beetles because
their larvae produce a very fine, powderlike frass in their
galleries (vs. bostrichids/false powderpost beetles and anobiids,
whose larvae produce coarser frass which also contains fine
wood fragments or pellets respectively). They are worldwide
in distribution, with about 11 species occurring in the United
Depending on the species, adults about 1/32-1/4" (1-7
mm) long. Body elongate, narrow, flattened, almost parallel-sided;
head, pronotum, and elytra (wing covers) about equal in width;
pronotum somewhat wider at front, head and often mandibles
visible when viewed from above. Color reddish brown to black.
Antennae with abrupt 2-segmented club. Elytra (wing covers)
often with rows of hairs (setae). First abdominal segment
ventrally much longer than other segments.
on the species, mature larvae up to about 1/4" (6 mm)
long. Color nearly white. Body C-shaped but with enlarged
thorax. Antennae short, 4-segmented. Spiracle of 8th (last)
abdominal segment 3 times larger than other abdominal spiracles.
Legs 3-segmented, ending with a long claw. However, 1st instar
larva straight-bodied, white, and bears a pair of small spines
at rear end.
(1) Flat bark beetles (Cucujidae) with antennae usually long
and threadlike/beadlike, sometimes short with 2-4-segmented
club, elytra (wing covers) usually lack hairs. (2) False powderpost
beetles (Bostrichidae) usually cylindrical in form, pronotum
with rasplike teeth at front, head usually not visible from
above. (3) Bark and ambrosia beetles (Scolytidae) are cylindrical
in form, antennae elbowed and clubbed. (4) Pinhole borers
and ambrosia beetles (Platypodidae) cylindrical in form, antenna!
club large, flat, 1-segmented. (5) Deathwatch beetles (Anobiidae)
with hoodlike prothorax, concealing head from above, last
3 antenna! segments lengthened and/or expanded.
AND SIGNS OF INFESTATION
Exit holes are round, and depending on the species, range
from 1/32-1/16" (0.8-1.6 mm) in diameter. Another indication
of an infestation is the accumulation of piles of very fine
powderlike dust beneath the exit holes or on the wood. This
dust/frass contains no pellets (like anobiid's) and falls
easily from the hole instead of being packed in (like anobiids
an economic viewpoint, the 2 most important Iyctids in the
U.S. can be briefly characterized as follows:
Southern Iyctus beetle, Lyctus planicollis LeConte. Adults
black; antennal 10th segment wider than long; prothorax usually
with a median, broad, shallow depression; elytra (wing covers)
with space between striae (longitudinal furrows) composed
of 2 regular series of elongate punctures (pits) and separated
by rows of fine, long hairs; length about 1/4" (5 mm)
but males much smaller; distributed throughout the United
2. Velvety powderpost beetle, Trogoxylon parallelopipedum
(Melsheimer). Adults rusty red-brown to black, densely covered
with short yellowish hairs not arranged in rows; antenna!
10th segment not wider than long; lateral margins of prothoax
converge behind (towards wing covers); length about 1/8"
(2.5-4.3 mm); found throughout the United States.
Female Iyctids lay their eggs (15-50) in exposed wood pores,
cracks, or crevices. Eggs are never deposited in/on waxed,
polished, painted, or varnished surfaces. The larvae tunnel
only in the sapwood and usually tunnel with the wood grain.
As they bore, the larvae loosely pack their tunnels with very
fine powderlike dust (like talcum powder or flour). After
several molts requiring 2-9 months, the mature larva bores
to near the surface and constructs a pupal chamber and pupates.
When the adult emerges, it bores straight to the wood's surface
and exits/emerges. Indoors, adults usually emerge in late
winter or early spring and with little feeding, mate. Under
very favorable conditions, developmental time (egg to adult)
usually requires 9-12 months, but may be as short as 3-4 months
or as long as 2.5-4 or more years. Although some Iyctids are
strong fliers, most tend to lay eggs in the wood from which
they emerged. Since Iyctid larvae cannot digest cellulose,
they feed only on the cell contents which is primarily starch,
but also sugar and protein.
Lyctids attack the sapwood and only that of hardwoods, usually
less than 10 years old. They attack both lumber and manufactured
products; they also attack structural timbers but hardwoods
are rarely used for this purpose today because of their cost.
The wood moisture content required for beetle development
is 8-32%, with greatest activity at 10-20%. Adults are active
at night, readily fly, and are attracted to light.
are usually brought into structures in wood which contains
their eggs and/or larvae. This wood is typically infested
during drying time or storage. Finish on wood prevents egg
usually attack oak, hickory, and ash, but will attack other
native and tropical hardwoods. Lyctids often attack bamboo.
First, determine if the infestation is active. If it is, then
prescribe replacement, localized pesticide application, or
fumigation, whichever is the least expensive to achieve control.
See the introductory section for details.