Thom Smith | Naturewatch: Use caution spraying carpenter bees' nests


Q: Last year I had four hummingbird feeders that were used constantly. This year, I have the same feeders in the same places with no hummingbird activity at all. Any ideas as to what the problem is?

How do I get rid of carpenter bees and keep them away as they are making holes in our shed?

A: I received several similar questions over the past 10 days, and will begin with the carpenter bees. On the bright side, these bees are important pollinators, especially flat or open flowers, and are only minor pests in most instances, although over time the damage may, in some cases, be considerable. One immediate approach to deter damage is to paint wooden surfaces.

To be more conservative, you can monitor their damage for a few years and, if it appears to be getting worse, consider a lethal approach. The carpenter bees that are buzzing about are males and are pretty harmless, except for a strong impulse to pass on their genes. It is the females that excavate those neat holes just over a half-inch in diameter in unfinished softwood.

In addition to decks, eves (I nearly fell off the ladder as I sprayed tunnels near the peak of our old house in Dalton some years ago. I can still recall the feeling in my stomach and my heart palpitations as I regained my balance). They also search out wood siding and window frames, and will use outdoor furniture, including picnic tables. Painted and pressure-treated wood is rarely, if ever chosen.

While females can sting, they rarely do so unless provoked. They also use the same holes from year to year. Do not spray bees indiscriminately! We rely on them to insure pollination of our food crops.

Tim Johnson, director of horticulture for the Chicago Botanic Garden, suggests, "Should you decide to control them at some point in the future, you can apply a preventive spray of carbaryl or a synthetic pyrethroid to the wood surfaces that are attracting the bees. Be sure to read instructions for applying any pesticide and time it properly for effectiveness. These products have residual effectiveness for about two weeks, so a repeat spray may be needed [during May]. Tunnels that have already been excavated are best treated by puffing an insecticidal dust into the hole. Leave the holes open for a few days before plugging to allow the bees to contact and distribute the dust."

Hummingbird update

Hummingbirds ran into terrible weather earlier this spring on their journey north, and I am relatively at ease saying the reason for no hummingbird activity at your feeders is the result of that inclement weather; "your" birds didn't survive the trip.

I would not give up, but be patient, others may find the feeders. And there is always the offspring of this summer's successful broods dispersing and looking for food sources. A colorful flower garden will help entice them. It is also important to have feeders clean, full, and at the ready for hummers heading south this coming fall.


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