Carpenter Bees

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COMMON NAME:
Carpenter Bees
SCIENTIFIC NAME:
Xylocopa spp.
CLASS/ORDER/FAMILY:
Insecta/Hymenoptera/Anthophoridae
INTRODUCTION. Carpenter 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 United States.
RECOGNITION. Adult 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).
SIMILAR GROUPS. (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.
REPRESENTATIVE SPECIES.
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.

2.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.

3.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
smoky.

4.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.
BIOLOGY. 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).

The 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.
HABITS. 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.

Male 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.
CONTROL. 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 can
emerge.

Carpenter 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.

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