Size: |
Deathwatch beetle (anobiid) adults are 1/32-3/8 in
(1.1-9 mm) long; those in structures are usually 1/8-1/4 in (3-7 mm)
long. Mature larvae are up to about 1/2 in (11 mm) long. |
Characteristics: |
Deathwatch beetle (anobiid) adults are 1/32-3/8 in (1.1-9 mm) long;
those in structures are usually 1/8-1/4 in (3-7 mm) long. Mature larvae
are up to about 1/2 in (11 mm) long. |
Color: |
The adult deathwatch beetle is reddish brown to nearly black, sometimes
with areas of pale hairs. Larva is nearly white. |
Droppings: |
Powdery frass containing pellets that are gritty and lemon-shaped
in softwoods, but tightly packed in hardwoods. (Two anobiids do not
produce pellets, but their frass is tightly packed.) |
Geographic Range: |
Deathwatch beetles (anobiids) are found around the world, with
310 species in the United States. |
Comparison with other species: |
Anobiids or deathwatch beetles are more common than Powderpost
Beetles (lyctids) and False Powderpost Beetles (bostrichids). The
name deathwatch, for some species, refers to the mating call, a tapping
sound made by jaws hitting the wood walls of their tunnels. When heard
while sitting through the night with a sick person, there was a superstition
that the invalid would soon die. Bostrichids have heads that are not
easy to see from the top, short antennae with compact clubs, and rasp-like
teeth. Lyctids have flat bodies, with heads easy to see from the top.
Bark and ambrosia beetles have elbowed antennae with symmetrical clubs.
Dermestid beetles have antennae with symmetrical clubs. |
Habitat: |
Sapwood of softwoods and hardwoods with a moisture content of 13-30%. |
Food: |
Studies indicate that anobiids, unlike bostrichids and lyctids,
can digest wood cellulose, due to yeast cells in their digestive tracts.
|
Biology: |
Nocturnal. Female deathwatch beetles (anobiids) lay their 20-60
eggs in cracks, in old exit holes, and under surface splinters of
wood. After hatching the larvae bore against the woodgrain a ways,
then turn and go along the grain, packing their frass and fine wood
fragments into the tunnel behind them. In a softwood (conifer) this
mixture feels gritty due to the shape of the pellets; in a hardwood
(broadleaf) the mixture is tightly packed and not gritty. With each
larval molt and for pupation the tunnel is made wider. The adult bores
straight to the surface of the wood to exit. (This differs from bostrichids,
which bore almost to the surface first before pupating.) The adult
does not feed, but looks for a mate. Development from egg to adult
takes 1 year in good conditions, but often 2-3+ years indoors. |
Invasion: |
Female deathwatch beetle usually lays eggs on the same wood from
which she emerged. |
Damage: |
Deathwatch beetles are wood destroying insects that cause damage
to structural timbers, lumber and lumber products, especially in the
southeastern states and in moist coastal states. In structures, most
species attack only older wood 9-10+ years old. |
Detection: |
- Round exit holes, diameter 1/16-1/8 in (1.6-3.2 mm) with piles
of gritty powder nearby.
- Spring: new exit holes.
- Summer: new holes, adults present.
- Fall: larvae still active inside wood.
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