The attic and roof cavities in most Boise homes don’t get much attention. You go up to grab a box, notice the insulation looks disturbed or find droppings along a joist, and suddenly the question is what’s been living up there. Insulation is warm, dry, quiet and easy to tunnel through, which makes it appealing to several kinds of pests.
Here’s what you’re most likely to find in Treasure Valley roof cavities, the signs to look for and how to keep the space clean.
Why Pests End Up in Roof Cavities
Boise summers push attic temperatures high and winters drop outdoor temperatures well below freezing. Pests move to the attic for the steady shelter it offers in cold months and for the gaps that make it easy to get there: unscreened soffit and gable vents, gaps where the roofline meets siding, holes around plumbing vents and wires, and tree branches touching the roof.
Pests Commonly Found in Attic Insulation
Mice and rats
Rodents are the most damaging attic pest. They tunnel through insulation, flatten it into runways and pull it apart for nests, which cuts its effectiveness. They also chew wiring and leave droppings and urine that contaminate the insulation. Mice need a gap about the size of a dime; rats need about the size of a quarter. Our rodent identification guide helps tell them apart.
Spiders
Spiders settle into attics where they find insects to eat. Webs along rafters, around vents and in corners are the usual sign. See our post on spiders found in attic insulation for more.
Wasps in soffits and eaves
Paper wasps and yellow jackets nest in soffits, eaves and gaps along the roofline, and sometimes inside the attic itself. If you see wasps going in and out of one spot near the roof, don’t plug it, which can drive them inward.
Fall invaders
Boxelder bugs, stink bugs and lady beetles slip in through attic vents and roofline gaps in fall and spend the winter in insulation and wall voids. They show up on upstairs windows on warm days.
Carpenter ants
Carpenter ants nest in damp or damaged wood, so roof leaks, condensation problems and wet sheathing can attract them. Piles of fine sawdust-like material under rafters or large winged ants in spring are signs to look for.
Signs of Pests in Your Attic
- Droppings along joists, on top of insulation or near the attic hatch
- Tunnels, flattened paths or bunched nesting material in insulation
- Chewed wires, ductwork or stored boxes
- Scratching or scurrying sounds in ceilings at night
- Webs, dead insects or large numbers of insects around vents and windows
- Wasps coming and going from a spot on the roofline
Cleaning Up Contaminated Insulation
Rodent droppings and urine in insulation can carry disease. Don’t sweep or vacuum droppings dry. The CDC recommends ventilating the space, wearing gloves and wetting droppings with a disinfectant before removing them. Read the CDC’s rodent cleanup guidance before tackling an attic. Heavily soiled insulation usually needs to be removed and replaced, and that should happen after the rodents are gone and the entry points are sealed. Our article on rodent removal from attics explains what that process involves.
How to Keep Pests Out of Your Roof Cavities
Seal entry points
- Screen soffit, gable and ridge vents with sturdy metal mesh.
- Seal gaps around plumbing vents, wires and the roofline.
- Repair damaged soffits and fascia.
- Close gaps around the attic hatch and any recessed lights from the living space.
Manage moisture
Make sure bathroom and kitchen fans vent outside, not into the attic. Fix roof leaks promptly and check that attic ventilation is working so condensation doesn’t build up.
Trim trees and check the outside
Cut branches back from the roof so rodents and ants can’t use them as bridges. Keep gutters clear and check the roofline each spring and fall.
Inspect a couple of times a year
A quick look in spring and fall catches problems early. Bring a flashlight and look for droppings, tunnels and webbing near the eaves and around vents.
When to Call a Professional
Call for help if you find fresh droppings, hear activity in the ceiling, see chewed wiring or notice wasps going in and out of the roofline. Attic work often means crawling across joists in a hot or cold space with contaminated insulation, and finding every entry point along a roofline takes experience. A technician can locate the gaps, set traps where rodents are traveling and recommend sealing.
Attic Pest Control With ProGuard
Mice, rats, spiders, ants, wasps and fall invaders are core pests in our residential pest control. We offer quarterly, bi-annual and one-time service, and quarterly service plan customers get free return visits. Rodent service is included at no extra cost with quarterly service plans; traps and materials are billed separately. For more on rodent work, see rodent control in Boise.
Get Your Attic Checked
ProGuard is based in Eagle and serves homes and businesses in Boise, Meridian, Nampa, Caldwell, Star, Middleton, Emmett and Garden City. Call (208) 352-2062 or contact us to schedule an inspection.