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  • Michael Kesecker
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Carpenter Bees:

 It is Carpenter Bee season and this year more than often than last year, they are spotted buzzing around homes and back yards worrying many. But fear not, as Carpenter Bees are more a friend than a foe.

There are over 500 species of Carpenter Bees (Xylocopa) that can be found throughout the world. In California and Marin the California Carpenter Bee (Xylocopa Californica) nest in trees and wooden structures. Carpenter Bees do not feed on wood like termites but forage on pollen like their common honeybee counterparts. They are easily recognized by their dark shiny charcoal black color with a beautiful well-rounded body. They are often noticed during the warm season from early spring to late fall when we see them flying around our structures and back yards busy preparing their nest for winter. Males are the same color and shape but do not have a stinger and never attack, while female carpenter bees do have a stinger but will only defend themselves and their nest when provoked.

Nesting and Infestations:

Carpenter Bees carve a large hole opening that leads to one main channel with several small alcove chambers each housing one egg. Six to 8 eggs are laid in the fall where they remain dormant all winter. The eggs will hatch and the bees will exit the wood the following spring. The eggs closest to the surface will exist first allowing the deepest laid eggs to hatch and exit last. To this day, it remains a great mystery to entomologists how the first eggs laid in the rear chambers are the last ones to hatch, while the last eggs laid will hatch first. Most homeowners will notice pencil like fine shavings (or frass) below the holes where the bees carve the wood to create their galleries and chambers within wood members. We often see them in trim boards, rafter tails, roof fascias, arbors, pergolas and other exposed wood members. Carpenter bees will infest any type of softwood including redwood and cedar wood members,

Carpenter Bees are pollinators and contribute greatly to the local ecosystem. They are not considered a major structural pest like termites or wood boring beetles as homeowner usually find them annoying and will try to get rid of them before wood members can be severally damaged. They can also be often found in dead trees and woodpiles, fences, sheds, balconies and decks. Carpenter Bees are mostly solitary insects, sometimes living in small groups with mothers, daughters or related siblings living nearby but not sharing the same nest holes. Left alone they will not be aggressive and can become a fun or annoying distraction.

Preventing and Eliminating Carpentar Bee Infestations: 

Carpenter Bees being indigenous to California, the best is to prevent infestations through preventative maintenance and treat when necessary.

1)   Patch, caulk and paint or stain all exposed outside wood members (eaves, arbors, pergola, decks, balconies, etc.) to prevent infestation and deter re-infestation..

2)      Avoid stacking woodpiles against the siding of a home or even close to entry/exit ways.

3)      Keep limbs, vines, bushes and vegetation away from roof, decks, fences, arbors and siding.

4)      Seal cracks and openings in the eaves and siding, especially at pipes, cables and other protrusions.

5)  Call a beekeeper to remove and relocate the infested wood member if possible, thereby allow bees to continue pollinating somewhere else.

6)  Otherwise call us for a treatment to the galleries and plugging the holes with epoxy wood filler. We use epoxy over bondo type material that bees can remove to continue their business.

Horntail Wasps

The horntail wasps are rare in structures and at 1 to 1.5” inch long with an additional ¾” long stout ovipositor (egg-laying device) Horntail Wasps appear more ominous than they really are.

There are about 20 species of Horntail Wasps form the Siricdae family and while adults do not eat wood, their larvae do. Some species have beautiful colors ranging from brightly color metallic blue to yellow, red and black. Some lay eggs into hardwood but most favor softwood such as pine. The infestation starts in dead and burned trees after a forest fire where the female likes to lay her eggs. Once the tree is harvested, cut into lumber and used in construction, the dormant eggs can hatch if the wood is not kiln dried to kill the eggs and larvae. The larvae will molt and the adults emerge several years later sometimes scaring occupants of a structure. Fortunately these insects don’t re-infest structures and no treatment is needed. When Horntail Wasps emerge they seek to go outside and homeowners should simply let them go out and caulk and paint the exit hole left behind.

Call us at Sonoma County: (707) 838-629 | Marin County: (415) 258-8200 for additional information.