Woodpeckers – Carpenter Bees and Residential Siding
Information from Cornell Lab of Ornithology
Woodpeckers are 17 to 40 cm (7 to 15 inches) long, have short legs, sharp-clawed toes and stiff tails. Most woodpeckers feed on wood-boring insects, insects on trees and the ground, vegetable matter, berries or tree sap. The northern flicker (Colaptes auratus) is responsible for most woodpecker damage to homes in the Northeast. It is identified in flight by a yellow or salmon tint under the wings and tail feathers. Flickers have black spots on a tannish-white breast and belly. Males have a black or red mustache extending from the gape of the beak to below the eyes. The hairy woodpecker (Picoides villosus) and downy woodpecker (Picoides pubescens) also occasionally cause problems.
Woodpeckers hammer on the sides of houses and other buildings to attract mates, to establish and/or defend a territory, to excavate nesting or roosting sites, and to search for insects. Wooden shingles, cedar or redwood siding, metal or plastic guttering, television antennas and light posts are selected as drumming sites because these materials produce loud sounds. Woodpeckers frequently damage cedar, rough pine and redwood siding and some synthetic stucco exterior finishing. Plywood and Masonite are less frequently damaged.
Houses with aluminum or vinyl siding are not typically prone to woodpecker damage. However, if the fascia boards of the house are made of wood, they may sustain damage from woodpeckers drumming on the wood in which case there will be very small holes in clusters at specific points on the fascia boards. The fascia boards may also become infested with carpenter bees.
If the siding of the house is completely aluminum or vinyl, the primary aggravation may be the sound of a woodpecker drumming on a gutter or chimney. Drumming behavior is probably to establish a territory or attract a mate and will most likely stop once breeding has begun in the spring. Drumming damage is often minimal.
If the house has stained cedar clapboards and is located in a wooded region or woodpecker “hot spot” (an area of high woodpecker population and activity), the house is particularly susceptible to damage, especially if the stain is an earth tone such as brown, dark red, or dark green. There can be a few different types of damage:
- Holes larger then two inches in diameter may be drilled by the woodpecker into the siding, usually between the seam of the two clapboards (Figure 1). Often these holes go through the siding and into the insulation. These are most likely the beginnings of roosting or nesting holes. Smaller, unfinished holes as well as scrapings along the upper board usually surround larger holes.
- Scrapes and holes on the corner siding or corner boards of the house may be due to drumming or nesting/roosting behavior. Such damage is less often a case of foraging for insects.
- Holes in the fascia boards may be either the result of drumming, in which case there are usually very small holes in clusters at specific points on the fascia boards, or the result of woodpeckers foraging for carpenter bee larvae. (See Carpenter Bee Description Below) If the house has painted cedar clapboards, unless the house is in a woodpecker hot spot, there is often no damage to the siding, especially if the house is painted in shades of white, pastels, or other bright colors. Damage to the fascia boards could be the result of woodpeckers drumming, evidenced by very small holes in clusters at specific points on the fascia boards, or the result of woodpeckers foraging for carpenter bee larvae. Damage may be similar to that described for stained cedar clapboards.
Woodpecker nesting/roosting attempts on cedar clapboards
Woodpeckers do not seem to be attracted to this type of siding, so damage is usually minimal. There may be drumming damage, in which case there are very small holes in clusters at specific points on the fascia boards, or carpenter bee damage to the fascia and/or corner boards. Occasionally a woodpecker will try to excavate roosting or nesting cavities into the hardboards.
Woodpecker nesting/roosting attempts into hardwood siding
Type 111/ Grooved Plywood
If the house is made of stained plywood that mimics the look of boards backed by battens (also known as Type 111) and if there are woodpeckers in the area, the house is very susceptible to damage. There is less damage when the plywood is painted. (Type 111 is made from sheets of plywood into which vertical grooves are cut.) These grooves expose core gaps in the middle layers of the plywood. The wood may sustain a few different types of damage:
- Larger and smaller holes along the corner boards or on the siding of the house, resulting from nesting or roosting attempts, drumming, or insect foraging.
- Almost perfectly horizontal rows of small holes across the boards. These holes are the result of woodpeckers foraging for insects, such as the leafcutter bee, which use these gaps as egg-laying chambers. (Figure 3)
- Damage to the fascia boards may be the result of drumming, in which case there are very small holes in clusters at specific points on the fascia boards, or it could be carpenter bee damage.
Type 111/ Grooved Plywood
Woodpecker foraging holes in vertically grooved plywood siding
Resawn Cedar Shakes
If the house is made of stained resawn cedar shakes, especially if the stain or paint is an earth tone, it is susceptible to damage, particularly in a woodpecker hot spot. The damage is usually characterized by large and small holes along the corners of the house, between the bottom of one shake and the top of the next (Figure 4). The damage may be clustered around wires, which are used as perches, attached along the house. These holes look as though they could be roosting or nesting attempts. Smaller holes along the corners could be the result of drumming.
Holes on the fascia boards could be the result of woodpeckers foraging for carpenter bees.
Possible roosting/nesting attempts along with drumming damage on cedar shakes
If the house is made of stained cedar shakes or shingles, the house is particularly susceptible to damage, especially in a woodpecker hot spot. (Painted houses often have damage to a lesser extent than stained houses.) Damage is usually characterized by vertical rows of small holes that follow the crack between two bottom shingles up into the overlapping top shingle (Figure 5). This is the result of woodpeckers foraging for insects such as leafcutter bees, which may use these cracks for egg-laying or shelter.
The damage may also be characterized by large and small holes along the corners of the house, between the bottom of one shake and the top of the next (Figure 6). The damage may be clustered around wires, which are used as perches, attached along the house. These holes look as though they could be roosting or nesting attempts.
Damage may also be in the form of very small holes along the corners of the house possibly resulting from drumming behavior.
Holes on the wood fascia boards may be a result of drumming, evidenced by very small holes in clusters at specific points on the fascia boards, or foraging for carpenter bees.
Nesting Holes in Cedar Singles. Damage due to woodpecker foraging for insects on cedar shingles
If the house is made of stained tongue-and-groove or board-and-batten cedar siding there may be damage to the house, especially if the house is located in woods or in a woodpecker hot spot. (Damage is often to a lesser extent if the house is sided with painted hardboard.) Large, medium, or small holes at the seams of the boards usually characterize damage to these siding types (Figures 7 and 8). There might also be scrapes between the boards. These holes and scrapes may be the result of roosting and nesting attempts.
There may be smaller holes along the corner boards or fascia boards. These may either be the results of drumming behavior, evidenced by very small holes in clusters at specific points along the boards, or the result of searching for carpenter bee larvae.
Nesting/Roosting cavity along with very small drumming
holes on cedar tongue-and-groove
Carpenter bees are often confused with bumblebees. However, carpenter bees are larger, have bright yellow, orange, or white hairs on their thorax, and have shiny black abdomens (Figure 9). Male carpenter bees do not have stingers; they fly around flowers looking for receptive females. Females do have stingers, but rarely sting. Female carpenter bees drill small perfectly round holes the size of a dime into fence posts, wooden fascia boards, wood overhangs, trees, or other wood structures. She drills straight into the wood about an inch or two, and then turns 90 degrees. This portion of the nest becomes the egg chamber. Single eggs are laid into cells constructed within the egg chamber. A mixture of pollen and nectar is placed alongside the egg, and the cell is sealed with chewed wood pulp. The eggs hatch and the larvae develop into adults, chew through the seal, and emerge in late summer.
Males and females overwinter in abandoned nest tunnels and emerge in April or May. Adult female carpenter bees often return to their place of birth and build their own egg laying chambers extending from previous years’ tunnels. A single tunnel one year can become two or three the next. The original entrance hole of the female carpenter bee is usually on the undersides of the wood, there are often large patches of yellowish bee excreta exuding from these holes. Carpenter bee larvae are noisy and tend to attract woodpeckers who will drill holes along the tunnels feeding on the larvae. This activity results in long trenches and holes about 0.5 to 1 inch deep along the wood.
Adult Carpenter Bee
Woodpecker damage due to foraging for carpenter bee larva on fascia boards of a house
Woodpecker damage due to foraging for carpenter bee larva on cedar trim boards of a house
Leafcutter bees, of the genus Megachilidae, are non-aggressive native bees important as pollinators. They nest in large pithy plants such as roses, in soft rotted wood, and in small crevices and cracks within wood. Leafcutter bees are about the size of a honeybee, but darker with light bands on their abdomens. Solitary bees, individual females dig out nesting areas, create nest cells, and provide young with food. After the nest is made, the females collect fragments of leaves which they cut in a smooth semi-circle about 3⁄4 inch in diameter from the edge of leaves. These pieces are carried back to the nest and used to line the cells. The cell is provisioned with a mixture of nectar and pollen. The egg is laid, and the cell is sealed. The finished nest cell somewhat resembles a cigar butt.
Leafcutter bees will often develop nest sites within specific types of house siding. These nests then attract woodpeckers that will damage the siding in their foraging. Type 111 siding (vertically grooved plywood) has horizontal core gaps exposed when vertical grooves are cut into the plywood. Leafcutter bees will burrow into these gaps to lay their eggs. Woodpeckers will drill horizontal rows of small holes into the siding following these core gaps in an attempt to feed on the larvae. Cedar shakes have many cracks between abutting and overlapping shakes. Leafcutter bees will follow the crack between two adjacent shakes, upward underneath the overlapping upper shakes in order to lay their eggs. Woodpeckers follow these cracks, drilling vertical rows of small holes into the shakes in their foraging attempts.
Psyche casta, known commonly as grass bagworms, is another insect type that woodpeckers look for on houses. The larvae of the Psychidae resemble tiny caterpillars. They construct cases made from fragments of grasses and other plant materials and when the larvae pupate, the case or bag is attached to a tree trunk, a wooden fence, or the siding of a house. Woodpeckers will hammer on a house while searching for the treats hidden inside these inch long bags.