P&PDL Picture of the Week for
April 24, 2006

Carpenter Bees

Timothy J. Gibb, Extension Diagnostician, Department of Entomology, Purdue University

Many complaints are currently being forwarded to the laboratory concerning “large bumble bees that bore into wooden structures.” These are almost certainly carpenter bees. A carpenter bee approximates the bumble bee in shape and size but is nearly all black and has a much more naked (hairless) body. Often times, seeing a bee working around a nearly perfectly round entry hole in wood that is about 1/2 inch in diameter is a good diagnostic character. The hole goes straight into the wood for about 1-2 inches, then makes a 90 degree turn and runs with the wood grain for some 4-6 inches. The female bee fills 6-8 cells (separated from one another by partitions of wood pulp) with pollen and nectar.

Each of these cells contains one bee larva. After the cells are completed, the female seals the tunnel and soon dies.  Larvae inside the cells mature by late August and new adults emerge by early September. These adults forage for nectar but eventually reenter the tunnel (or a nearby one), clean it, and then overwinter in it. The cycle starts anew the following spring. Note that carpenter bees may refurbish an existing tunnel instead of boring a new one, that an infestation may persist for several years or more, and that new tunnels  are often constructed near old ones.

The carpenter bee actually causes little serious damage, although continuous tunneling in wood may weaken the structure. Perhaps the biggest problem is the annoyance and fear associated with the large carpenter bee. Males patrol the area and often fly about the faces of people; however, they cannot sting. The females do not defend their nest, but will sting if mishandled.

Control can be safely and effectively accomplished by dusting into the tunnels with 5% Sevin, leaving them open for a day or so, then plugging the opening with a
dowel or wood putty to prevent future use.

Click image to enlarge

Carpenter Bee


Flowering Dogwood Bracts (not petals!)

B. Rosie Lerner, Extension Consumer Horticulture Specialist

Botanically speaking, the showy white structures that most folks think of as the petals of a dogwood flower are actually floral bracts.  The definition of a bract is a modified leaf or leaf-like structure found just below an inflorescence (cluster of flowers). Bracts can be quite showy, in fact showier than the true petals, as is the case with flowering  dogwood, poinsettia, and bougainvillea.

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Dogwood Bracts

Dogwood Bracts

If you look closely at this dogwood inflorescence, you'll see a cluster of greenish flowers in the middle of a set of four showy white bracts that are notched at the tips. 

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service