5.7 Fabric Pests, Silverfish & Occasional Invaders
Key Takeaways
- Clothes moth larvae leave silk webbing and colour-matched frass, while carpet beetle larvae leave shed larval skins and no webbing — the fastest way to separate the two damage patterns.
- Adult clothes moths have non-functional mouthparts and cause no damage, so control targets larval harbourage and pheromone traps serve only as monitoring.
- Silverfish prefer cool humid conditions and starchy materials, while firebrats prefer hot dry sites near boilers, ovens and steam lines; both are ametabolous and moult as adults.
- Occasional invaders such as boxelder bugs, Asian lady beetles and western conifer seed bugs aggregate on sun-warmed south and west walls in autumn, so the exterior treatment window is late summer before entry.
- Sowbugs, springtails, earwigs and house centipedes indoors are moisture indicators, and correcting the water source outlasts any insecticide.
5.7 Fabric Pests, Silverfish & Occasional Invaders
[!NOTE] The pests in this section share one feature: the complaint arrives long after the cause. A hole in a sweater, a silverfish on the bathroom floor, a wall covered in lady beetles in October — each is the visible end of a process that started somewhere else, weeks or months earlier. Finding the source is most of the work.
Fabric Pests: The Keratin Feeders
Fabric pests digest keratin — the protein in wool, silk, fur, feathers, hair, and the dried remains of dead insects and animals. That defines where you search: not just the wardrobe, but under and behind heavy furniture, along carpet edges, in floor and wall junctions, in air ducts, in dead-insect accumulations in light fittings, and in abandoned bird and rodent nests in voids.
The two moths
- Webbing clothes moth (Tineola bisselliella) — small, uniformly buff to golden, with no wing markings, and it runs and hides rather than flying to light. Larvae spin silk webbing and feeding tubes over the material they are eating.
- Casemaking clothes moth (Tinea pellionella) — the larva carries a portable silk case that it drags along and hides in, often taking on the colour of the fabric it has fed on.
The two beetles
- Black carpet beetle (Attagenus unicolor) — adult a shiny black to dark brown oval; larva elongate and carrot-shaped, golden brown, tapering to a long tuft of tail bristles.
- Varied carpet beetle (Anthrenus verbasci) — adult small, rounded and mottled with white, brown and yellow scales; larva short, stout and banded with tufts of hair. Adults feed on pollen outdoors, so they enter through windows and around flowers brought inside.
Telling the damage apart
| Evidence | Clothes moths | Carpet beetles |
|---|---|---|
| Silk webbing or tubes on the fabric | Present | Absent |
| Shed larval skins | Absent | Present, often more numerous than live larvae |
| Frass | Colour-matched to the fabric eaten | Fine and gritty |
| Damage pattern | Grazed surface and irregular holes, often hidden under collars, folds and seams | Irregular holes, often along seams, plus damage to feathers and dead insects |
| Adults at windows | Uncommon — moths avoid light | Common — adults fly to light and to windows |
Control
- Find the source. In a stubborn case the source is usually not the damaged garment. Search dead-insect accumulations, an old wool rug under a bed, a bird nest in a soffit, a rodent carcass in a void, taxidermy, feather pillows or a felt piano action.
- Vacuum thoroughly and repeatedly, including carpet edges, beneath furniture, in floor cracks and along baseboards; discard the vacuum contents outside.
- Launder or dry-clean infested textiles. Soiled wool — perspiration, food, urine — is preferentially attacked, so cleaning before storage is genuinely preventive.
- Heat or freeze items that cannot be laundered; a sustained deep freeze at about −18 °C for several days kills all stages in most items.
- Store clean textiles in sealed containers; garment bags that are not airtight do not exclude a larva.
- Pheromone traps for monitoring only. They tell you a species is present and roughly where; they do not control a population.
- Targeted chemical in cracks, crevices, carpet edges and voids where labelled — never a broadcast application over textiles people wear.
Silverfish and Firebrats
Both are ametabolous: no metamorphosis, immatures identical to adults, and the adult continues to moult throughout its life.
| Silverfish (Lepisma saccharina) | Firebrat (Thermobia domestica) | |
|---|---|---|
| Appearance | Uniformly silvery grey, carrot-shaped, three long terminal filaments | Mottled brown and grey, otherwise similar in form |
| Preferred conditions | Cool to moderate temperature, high humidity | Hot and dry |
| Where found | Damp basements, bathrooms, beneath wallpaper, in stored paper and books | Around boilers, furnaces, ovens, bakeries, steam and heating conduits |
| Food | Starch, dextrin, paper sizing, book bindings, wallpaper paste, cereals, some fabrics | The same materials, in hot locations |
Both are long-lived and slow to develop, so populations build quietly and a treatment takes time to show. Control is dehumidification and moisture repair first, removal of stored paper and cardboard second, and desiccant dust or residual in voids, wall junctions and beneath fittings third. Because they are chewing insects, baits are available and useful in sensitive areas.
Occasional Invaders
These pests do not breed indoors. They come in from outside for shelter, moisture or warmth, and they leave, die, or accumulate at windows.
The autumn aggregators
- Boxelder bug (Boisea trivittata) — black with red-orange markings, associated with Manitoba maple.
- Multicoloured Asian lady beetle (Harmonia axyridis) — orange to red with variable spots and an "M" or "W" mark behind the head; releases a staining, foul-smelling defensive fluid when disturbed, which is the real complaint.
- Western conifer seed bug (Leptoglossus occidentalis) — large, brown, with flared hind legs; startlingly loud in flight.
- Cluster fly — covered in section 5.6, and controlled on exactly the same schedule.
All of these gather on sun-warmed south- and west-facing walls in late summer and autumn, then work into gaps at siding, soffits, fascia, window frames and utility penetrations to overwinter in voids.
[!IMPORTANT] The whole programme is a timing decision. Exclusion plus a labelled exterior wall treatment in late summer, before entry, works. The same treatment in November, after the insects are already inside the voids, does not. Once they are indoors, vacuuming is the correct interior tactic — spraying a wall void full of overwintering insects produces a mass of bodies that feeds dermestid beetles and creates next spring's fabric pest complaint.
The moisture invaders
| Pest | Recognition | What it tells you |
|---|---|---|
| European earwig (Forficula auricularia) | Forceps-like cerci at the abdomen tip; nocturnal | Damp mulch, leaf litter or debris against the foundation |
| House centipede (Scutigera coleoptrata) | Long legs, very fast, flattened | A predator — it is eating other insects you have not yet found |
| Millipedes | Two pairs of legs per segment, slow, cylindrical | Heavy rain plus organic debris; mass migrations |
| Sowbugs and pillbugs | Crustaceans with plated backs; pillbugs roll into a ball | Gill breathers — indoors they mean liquid water |
| Springtails | Minute, jump when disturbed | Persistent damp: over-watered planters, wet drywall, condensation, a leak |
| Crickets | Chirping, jumping, active at night | Entry at grade level; they damage fabrics and paper |
The control is nearly identical in every row: repair the moisture, remove the debris and mulch banked against the wall, re-grade so water drains away, seal at grade, screen the vents, and fit door sweeps. A perimeter residual is a supporting tactic with a service life measured in weeks; the drainage repair lasts for years.
[!TIP] A legal note on the exterior band. Treating the foundation and the strip of ground beside it as part of controlling an invader entering the building is a use integral to a structural extermination under s. 30 of O. Reg. 63/09. Treating the lawn because the client wants fewer earwigs in the garden is a land extermination for a turf or ornamental purpose, and it needs a Landscape licence. The nozzle direction, not the product, decides which one you are doing.
A homeowner brings in a damaged wool blanket. The technician finds irregular holes, numerous shed larval skins in the fibres and along the carpet edge nearby, and no silk webbing. Which pest is responsible and what does that imply for the search?
In early November a client reports thousands of Asian lady beetles emerging from wall voids into the living space. What is the correct advice?
Sowbugs and springtails are found regularly in a finished basement. Which combination of findings and actions best matches their biology?