My question is regarding very large black bees homing in on the eaves of my house.

Several years ago, I began seeing fat, 1-inch long bees in my backyard and, with every passing year, more appeared bobbing around the yard. I had an old redwood deck with a large pergola and watched one night in fascination as one bee at a time hovered around several holes in the redwood and disappeared inside. I discovered these enormous bees had bored many holes in the 6-by-6-inch beams of the pergola. I watched at dusk every night as the bees came "home" after they'd done their day's work. Droplets of wax and bits of sawdust appeared regularly on my patio table underneath.

I am somewhat of an environmentalist, do not use pesticides in my home or yard (except for flea control on my pooch). I contacted county pest control and UC Davis agriculture experts and, if I remember correctly, was told these were probably "carpenter bees," which are excellent pollinators.

Since the bee population was then declining, the preference was not to eradicate. Instead, I should poke pieces of steel wool in the holes to prevent the bees from entering, encouraging them to find nest areas elsewhere.

I spent quite a lot of time and energy doing this, but within a day or two was surprised to find the plugs of wool on the deck, obviously pulled out by the undeterred bees. I even witnessed the culprits carefully tugging at the steel wool with their large front legs until they succeeded and crawled inside.

Fast-forward a couple of years: Many holes, many bees. Deck and pergola dying of natural causes (35 years old), torn down, and hauled away in September 2008. Afterward, I sadly witnessed several bees buzzing around aimlessly without a home to go to. However, since it was fall, I figured they'd die out with the oncoming cold weather.

But more than two years later, the bees are still here and are now flying in narrow openings on the roof corners of my home.

My returning bee visitors come at dusk every night and very well may now be unwelcome attic roommates. These are not swarms, only single bees and not huge in number.

How big a problem is this and what should be done? I could really use your help! Seems a bee population boom may be in the offing!

– Jeanne Marcucci, Carmichael

According to UC master gardener Jeannie Claypoole, the bees may be nesting in your attic.

Assuming that some of your trespassing carpenter bees are females, they are boring tunnels in your wood to make nests, each of which will hold an egg and a supply of pollen for food. Adults overwinter, often in the tunnels, so you cannot count on cold weather to eliminate them.

If you are able to access the holes they are making in your eaves, one recommendation for managing them includes filling the holes with steel wool as you were previously told. However, you need to use caulk as well so your resourceful guys can't pull out the wool. This should be done when they have vacated the hole (during the day). After filling the holes, paint or varnish the repaired surface.

These bees are considered beneficial because they pollinate crops. But if their numbers are high enough to warrant your concern, you may want to treat the nests with a desiccant dust containing boric acid. When the larvae hatch, they essentially dry out and perish.

The dusts are low in toxicity to people and animals and are effective for a long period of time as long as they don't get wet.

• For more information about carpenter bees, go to www.ipm.ucdavis.edu and look for Pest Note 7417. You can also request this publication by sending a self-addressed, stamped 44-cent business-size envelope to: PN 7417, UC Cooperative Extension, 4145 Branch Center Road, Sacramento, CA 95827.

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