bees get their common name from their habit of boring into
wood to make galleries for the rearing of young. These are
worldwide in distribution with 7 species occurring in the
body length about 1/2-1" (12.5-25 mm); robust in form,
resembling bumble bees, but with top surface of abdomen largely
bare and shining. Hind tibiae with apical spurs. Front wing
2nd submarginal cell triangular; hind wing with a small jugal
lobe (lobe on rear margin near body).
(1) Bumble bees (Apidae) have hairy abdomen with yellow markings,
2nd submarginal cell somewhat rectangular to pentagonal, and
hind wings lack a jugal lobe. (2) Some robber flies (Diptera:
Asilidae) which resemble bumble bees, with only 1 pair of
wings. (3) Some hawk moths (Lepidoptera: Sphingidae) which
resemble bumble bees, with siphoning mouthparts.
1. The carpenter bee, X. virginica (Linnaeus), is the most
common eastern species and its range extends westward to Kansas
and Texas. It is about 1" (25 mm) long and closely resembles
the bumble bee except that the abdomen is black and shiny
instead of at least partially covered with yellow hairs. The
male has a yellow face, whereas, the female's is black.
The California carpenter bee, X. californica Cresson, is found
in the north Coast Ranges and the Sierra Nevada of California
and in Oregon's Cascade Mountains. This bee is 3/4-1"
(20-25 mm) long and both sexes can be mostly metallic green
or blue with grayish/dusky wings. The male's pronotum has
orange, yellow, or white hairs and its 1st abdominal segment
has whitish hairs.
The valley carpenter bee, X. varipuncta Patton, is found primarily
in the valleys and lower foothills of California and Arizona.
This species is about 3/4" (18-20 mm) long. The female
is shiny black with brilliant metallic purple, brassy, or
bronzy reflections, in stark contrast to the golden brown
or buff color of the male. The female's wings are somewhat
The mountain carpenter bee, X. tabaniformis Smith, is found
mostly in the foothills and mountains of Arizona, California,
Nevada, and Oregon. This bee is about 1/2-5/8" (12-17
mm) long and both sexes are black. The male's head has yellow
and white hairs mixed with black hairs.
Carpenter bees are not social insects and do not live in nests
or colonies. The adults overwinter, typically in abandoned
nest tunnels. In the spring, the survivors emerge and feed
on nectar. Then mating begins and extends into nest-construction
time. The mated female may either reuse an old gallery, construct
a new one by lengthening an old gallery, bore an entirely
new one, or extend a gallery from a common entrance hole.
The female typically bores a circular hole (same diameter
as her body) straight into the wood across the wood grain
for a distance equal to her body length. Then the gallery
takes a right-angle turn, usually with the grain of the wood
and parallel to the outer longitudinal surfaces. New galleries
average 4-6" (10-15 cm) long but galleries developed/used
by several bees may extend up to 10 feet (3 m).
female provisions each gallery cell starting at the closed
end of the gallery with a mass of pollen and regurgitated
nectar upon which she lays a single egg. This portion of the
gallery is then sealed off with a chewed wood-pulp plug, making
a chamber or cell. This process is repeated until a linear
series of 5-6 cells is completed, about 1 cell per day. Developmental
time (egg to adult) for the carpenter bee (X. virginica) is
about 36 days and for the mountain carpenter bee (X. tabaniformis),
it is about 84-99 days.
Females of the carpenter bee (X. virginica) will nest in a
wide range of woods, but prefer weathered and unpainted wood.
Valley carpenter bees prefer partially decayed live oak, deciduous
oak, eucalyptus, and other hardwoods. The California carpenter
bee nests in incense cedar and redwoods. The Mountain carpenter
bee is recorded as nesting in structural timbers.
carpenter bees tend to be territorial and often become aggressive
when humans approach, sometimes hovering a short distance
in front of the face or buzzing one's head. Since males have
no stinger, these actions are merely show. However, the female
does have a potent sting which is rarely used.
Carpenter bee control consists of treating each individual
gallery with an appropriately labeled pesticide. Dusts, wettable
powders, microencapsulated, and aerosol residual formulations
work best. Aerosol injection systems are probably the most
efficient and safest way to treat galleries, especially when
on a ladder. Do not seal the treated gallery for 24-48 hours
so that the female has time to be exposed to a lethal dose.
Newly matured bees should contact a lethal dose before they
bees rarely attack painted wood. They can be discouraged from
using wood by applying an appropriately labeled repellent
material such as one of the pyrethroids, and microencapsulated
or wettable powder formulations are best.