The male carpenter bee pictured on the left can be distinguished from the female by the white-yellow spot on it's head. So what difference does it make if it's a male or female?  The male has NO stinger.  Even though the female does have a stinger she is very passive and rarely stings. You would probably have to handle the female or maybe step on her while barefooted before she would sting you.
     Male                          Female
CARPENTER BEES & BUMBLE BEES

The female carpenter bee above looks a lot like the bumble bee in the picture on the right. On closer inspection you can see the carpenter bee has no hairs on her abdomen, that's the big black rear section of her body.
The bumble bee above can be distinguished from the carpenter bee on the left by the yellow hairs on the abdomen.
Like carpenter bees, the male bumble bee has no stinger. Bumble bees build a nest averaging 200 bees. The queen bumble bee is large, about the same size as a carpenter bee. The male and female brood are smaller, averaging about 3/8 to 1/2 inches long. Bumble bees rarely sting however, if their nest is in danger they will readily sting.  They usually build their nests in hollow trees, etc., but they will nest in insulation in crawl spaces and wall voids of houses.
Bumble bees are very benificial insects, pollinating flowers and plants. They should not be killed unless their nest location endangers human health.
The male carpenter bee, even though it has no stinger, will hover above a persons head a few inches out of reach, especially if their nest is closeby.  This can be very un-nerving, especially to someone that is not very fond of bees to start with.  Carpenter bees will pair up to mate while in flight. If one bee buzzing by your head is alarming try having two fly close by while attached to each other.  Although carpenter bees are beneficial in their pollinating of plants, the damage they do to wood exceeds their pollinating  worth.
Carpenter bees bore a hole on the side or underside of wood. The hole is perfectly round about 7/16 inch in diameter, and appears to have been made with a drill. They bore into the wood then make a 90 degree turn and bore a tunnel along with the grain of the wood. They are usually seen in unfinished, non-pressure treated wood such a redwood patio furniture or facia and soffit boards. Shed, open garage, and barn rafters are very popular places for carpenter bees to bore their holes.
Although carpenter bees prefer to bore into unfinished wood they will go into finished areas on ocassion. The picture above left shows a carpenter bee just getting started on a hole. In Maryland  they are most active making new holes in April and May. The picture on the right shows a female exiting a hole on a heavily varnished log house.
This is an interior view of a carpenter bee tunnel bored in a 2x4. In this instance the entrance hole was made and after turning 90 degrees the bees had extended the tunnel in both directions for a total of about 14 inches.
This shows how the carpenter bee uses the tunnel for her nest. A single egg is laid, and then the female will leave the nest and sting and kill another insect. The dead insect is placed next to the egg for food for the larva when it hatches from the egg. The female then builds a cell wall. She then repeats the process all over again. Each egg is seperated by a wall. It appears that there had been 6 eggs laid in this tunnel. Keep in mind that the last egg laid is the first one to reach maturity since the one closest to the hole has to exit first. Now there's a different kind of biological clock than the one humans refer to.
As if carpenter bees don't do enough damage on their own, the pictures above show where woodpeckers have pecked into the wood trying to get to carpenter bee eggs and larva. In many cases more cosmetic damage is caused by woodpeckers than what is caused by carpenter bees, not to mention the irritating noise that woodpecker is making on your house while your trying to relax inside. Woodpeckers are a protected species and cannot be killed by law.
As carpenter bees bore, besides spitting out the wood shavings they excrete bodily fluids. These shavings and excrement stick to the sides of buildings where ever holes are being made. Although the excrement helps in locating the holes for treatment, it is unsightly. Besides the excrement being unsightly is does not wash off easily and since many times carpenter bee holes are near the roof,  30 feet from the ground, makes cleaning their mess vey difficult.
Carpenter bees have been chewing away at this facia board for years. There is not much wood left in this board. 

Carpenter bee treatment usually involves injecting insecticide into each individual hole made by the bees.

As treatment was being rendered here, insecticide dust was blown into holes on one end of the board and it was coming out of holes 8 to 10 feet away. Carpenter bees had riddled this board from one end to the other.
Click on pictures to enlarge
Click pictures to enlarge
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