That large golden lozenge hovering around the bushes just might be a male Valley carpenter bee (Xylocopa varipuncta)–the Golden Snitch of the bee world. This time of year, these one inch long, quickly moving bees are not out to collect pollen. They are looking for a mate. Although it’s been reported that male carpenter bees are territorial, we’ve found they tend to avoid people and cameras! We were barely able to capture the image of the bee below as he darted around rose bushes, but never alighted. He did pause once as if to size us up before buzzing off again. Interesting fact: male carpenter bees do not have a stinger. Only the blue-black females have the ability to sting, yet they tend to be very docile creatures.
Big, docile, what’s not to like about these bees? The holes they bore into wood structures. Carpenter bees cause damage to wooden structures by boring into timbers and siding to prepare nests. The nests weaken structural wood and leave unsightly holes and stains on building surfaces. Sound, undecayed wood without paint or bark is usually selected for nests.
Nests usually consist of tunnels 1/2 inch in diameter and 6 to 10 inches deep that are partitioned into several chambers, each containing an egg and a supply of food
(pollen). Carpenter bees may use old tunnels for their nests, which they sometimes enlarge; several bees may use a common entry hole connecting to different tunnels. Over a period of time, tunnels may extend as far as 10 feet into wood timbers. Tunnels are vacated after the brood’s larval and pupal stages complete their development. Development from egg to adult may take about 3 months. Carpenter bees overwinter as adults, often in old tunnels, and there is only one generation a year.
Because bees are important pollinators, prevention is the best way to protect your home from a carpenter bee invasion. Fill depressions and cracks in wood surfaces so they are less attractive to bees. Paint or varnish exposed surfaces regularly to reduce weathering. Fill unoccupied holes with steel wool and caulk to prevent their reuse. Wait until after bees have emerged before filling the tunnels. Once filled, paint or varnish the repaired surfaces. Protect rough areas, such as ends of timbers, with wire screening or metal flashing.