Overwintering pests in Austin

Boxelder bugs and red-shouldered bugs

Adult boxelder bugs are about half an inch long, dark brown to black, with three red or orange lines behind the head and red edging on the folded wings. Young boxelder bugs are bright red and develop darker markings as they mature. They feed on seeds and plants outdoors.

Red-shouldered bugs are a similar Texas nuisance invader. Adults are oval, about half an inch long, brownish gray, with red eyes and red markings along the outer edges behind the head. Texas A&M AgriLife describes both groups moving into protected cracks around siding, foundations, doors and windows as temperatures drop. Their waste can stain household surfaces.

Sources: Texas A&M AgriLife Extension, Boxelder Bugs and Red-Shouldered Bugs (September 2011); University of Minnesota Extension, Boxelder bugs (reviewed 2023)

Stink bugs

A shield-shaped body is a useful stink bug clue, but not every brown stink bug is the brown marmorated species. Brown marmorated stink bug adults are mottled brown, with alternating light and dark bands on the antennae and along the abdomen. Ask for identification if those details are unclear.

University of Minnesota Extension describes brown marmorated stink bugs sheltering in buildings in fall and becoming visible on warm winter days. They do not reproduce or damage the home while overwintering. Disturbing or crushing them can release an unpleasant odor. This describes that species' behavior, not proof of a current Austin outbreak or the identity of every local stink bug.

Sources: University of Minnesota Extension, Brown marmorated stink bug (reviewed 2022)

Asian lady beetles

Multicolored Asian lady beetles have rounded, dome-shaped bodies. Their wing covers can be yellow, orange or red, and spots vary or may be absent. A dark M- or W-shaped marking on the pale area behind the head helps distinguish them from other lady beetles. Spot count alone is unreliable.

Texas A&M AgriLife's Austin specialist explains that Asian lady beetles can enter through cracks to find warm, dry shelter. They are useful aphid predators outdoors, so leave outdoor beetles alone when they cause no problem. Indoors they can release an odorous, staining defensive fluid and sometimes nip skin. Native lady beetles generally favor outdoor winter shelter; do not assume every orange beetle indoors is the Asian species.

Sources: Texas A&M AgriLife, Are swarming ladybugs harmful? (December 28, 2023); University of Minnesota Extension, Multicolored Asian lady beetles (reviewed 2021)

Why bugs come indoors

Cooling weather prompts these insects to seek shelter rather than household food. Sunny south- and west-facing walls can be gathering places for boxelder bugs. Small openings around window frames, door trim, utility entries and rooflines provide access to protected spaces. Finding them does not, by itself, mean your home is dirty.

An insect that entered in fall may remain hidden until warmth brings it into a room. Texas extension describes fluctuating winter temperatures stirring sheltered Asian lady beetles; Minnesota extension describes similar winter activity in boxelder and brown marmorated stink bugs. The insects do not all become active at once, so seeing another one after cleanup does not necessarily mean a treatment failed.

Work on exclusion before insects begin gathering outside. If fall is already here, repair accessible gaps now rather than waiting for a fixed calendar date. Northern-state migration dates are not an Austin schedule, and the cited sources do not establish this year's local population levels.

Sources: Texas A&M AgriLife Extension, Boxelder Bugs and Red-Shouldered Bugs (September 2011); Texas A&M AgriLife, Lady beetle invasion (February 24, 2017); University of Minnesota Extension, Boxelder bugs (reviewed 2023); University of Minnesota Extension, Brown marmorated stink bug (reviewed 2022)

Your sealing and prevention checklist

Start with the building's exterior and the places where you see insects gathering. Exclusion reduces entry; it cannot guarantee that no insect will get inside. Use materials suited to the surface, and leave high roofline work to someone who can do it safely.

1. Check doors and windows. Replace damaged weatherstripping, repair loose screens and fit door sweeps. If daylight shows around a closed exterior door, address the gap. Check the garage door's bottom seal too.
2. Seal unintended cracks. Inspect window and door trim, fascia, siding joints and the places where brick meets other materials. Use an appropriate exterior sealant. Do not caulk openings designed for drainage or ventilation.
3. Inspect utility penetrations. Close gaps around pipes, wires and cables with suitable materials without interfering with equipment. Do not block dryer exhausts, combustion-air openings or appliance vents; ask a qualified professional when unsure.
4. Repair vent screening. Check damaged attic and soffit screens and maintain ventilation. For masonry weep holes, use purpose-made pest-resistant inserts that preserve drainage and airflow, not solid caulk or foam.
5. Reduce shelter beside the house. Move firewood, stacked boards and debris away from walls, and prune plants touching the structure. This supports prevention but does not eliminate flying insects arriving from neighboring properties.
6. Monitor before the next cool spell. Note which wall, window or door has activity and recheck repairs. If large outdoor clusters recur, request an assessment before insects enter. Any pesticide use must follow the current label for the pest and application site.

Sources: Texas A&M AgriLife Extension, Boxelder Bugs and Red-Shouldered Bugs (September 2011); Texas A&M AgriLife, Are swarming ladybugs harmful? (December 28, 2023); University of Minnesota Extension, Boxelder bugs (reviewed 2023); University of Minnesota Extension, Multicolored Asian lady beetles (reviewed 2021)

Removing indoor bugs

Use a vacuum for accessible insects rather than crushing them against paint, curtains or furniture. Empty the collection container or remove and seal the bag promptly, following the vacuum manufacturer's instructions. Vacuuming does not necessarily kill lady beetles, and insects left in a vacuum can escape or create odors.

Do not rely on indoor spraying to stop insects emerging from hidden winter shelters. Minnesota extension recommends physical removal for indoor boxelder bugs and brown marmorated stink bugs and says indoor spraying is not effective for Asian lady beetles. Texas extension also says bug bombs do not rid homes of Asian lady beetles. Do not spray blindly into outlets, vents or wall cavities.

Avoid tearing into walls to chase a few insects. Record recurring locations instead. An exterior repair prevents future entry, but may not stop every insect already inside from appearing during winter.

Sources: University of Minnesota Extension, Boxelder bugs (reviewed 2023); University of Minnesota Extension, Brown marmorated stink bug (reviewed 2022); University of Minnesota Extension, Multicolored Asian lady beetles (reviewed 2021); Texas A&M AgriLife, Lady beetle invasion (February 24, 2017)

When to call Austin Pest Control

Request a free inspection when insects repeatedly appear in occupied rooms, large outdoor clusters return, the species is uncertain, or suspected entry points are inaccessible. A few correctly identified nuisance insects may need only removal and repairs, not whole-house treatment.

Tell us where you see them, when the activity began and whether you have a clear photograph. Austin Pest Control serves homes across Travis, Hays and Bastrop counties. Our Austin pest-control service page explains the inspection-led process and property-specific options. An inspection helps separate seasonal sheltering from a different pest problem; this guide does not promise an insect-free home.

Sources: University of Minnesota Extension, Boxelder bugs (reviewed 2023); Texas A&M AgriLife, Are swarming ladybugs harmful? (December 28, 2023)

• Pest control services in Austin
• Request Free Inspection