Sowbugs on a basement floor, a camel cricket that jumps at your face when you open the crawl space hatch, a centipede in the bath, silverfish behind stored boxes. Virginia produces all of these in quantity, and treating them is usually the wrong first move.
They are not really an infestation. They are a reading. Every one of them needs moisture to survive, none of them can live long in a dry space, and their presence in numbers says something specific about the building — the same something an inspector writes down on a wood-destroying insect report as conducive conditions.
Fixing what they are telling you costs more than a spray and solves more than one problem.
This is general information. What a crawl space actually needs is established by someone who goes into it.
What you are looking at
Sowbugs and pillbugs. Grey, segmented, seven pairs of legs; pillbugs roll into a ball and sowbugs do not. They are crustaceans rather than insects, they breathe through gill-like structures, and they die within days in dry air. Finding them indoors in numbers means a route in and damp on the other side of it.
Camel crickets. Humpbacked, long-legged, no wings, no chirp, and they jump toward what disturbs them rather than away — which is why they have a reputation out of proportion to the harm they do. They are a signature Virginia crawl space animal. They chew paper, cardboard and fabric in numbers.
House centipedes. Fast, many legs, alarming. They are predators, and what they are eating is other small arthropods in the same damp space. A house centipede is a report about your other insects.
Silverfish. Teardrop-shaped, metallic, moving in a fish-like wriggle. They favour humidity and starch — paper, book bindings, wallpaper paste, stored cardboard.
Springtails. Tiny, jumping, often in enormous numbers around a damp bathroom or a wet basement wall. Harmless and almost purely a moisture indicator.
The reading, and why it also appears on a termite report
Every one of these needs relative humidity that a properly dried crawl space does not have. So the list of things that produce them is short and specific:
A downspout discharging at the foundation instead of away from it.
No vapour barrier, or one that has been torn, folded back by a previous contractor, or never covered the whole floor.
Grading that falls toward the house rather than away.
Blocked or closed foundation vents, or a crawl space closed up without being conditioned.
A plumbing leak that has been running quietly.
Mulch piled against the siding, closing the gap the builder left deliberately.
Firewood or timber stacked against the house.
Read that list again with termites in mind. It is the same list. A wood-destroying insect inspector records exactly these as conducive conditions, whether or not there is an infestation, because they are what makes one likely. Mud tubes on the foundation →
That is the practical point of this page. The sowbugs are free information. Acting on them removes a termite risk that has not yet cost anything, and the repair is drainage and a vapour barrier rather than a treatment and a structural bill.
What to do
Go and look, with a torch. The crawl space, the basement corners, behind stored boxes. What you are looking for is not insects but water: staining on the foundation, a damp patch under a pipe, condensation on ductwork, a vapour barrier that stops halfway.
Check outside after rain. Where does each downspout discharge? Does the ground slope away from the wall or toward it? Is mulch touching the siding?
Move stored cardboard off the floor. It holds moisture, it feeds silverfish, and it hides what you are trying to see.
Do not treat first. A perimeter spray kills the visible generation and the space refills, because the space is still wet.
Photograph what you find, particularly a torn or missing vapour barrier — that is the item most often quoted for, and a photograph makes the quote comparable between companies.
The order that saves money
Water away from the building. Downspout extensions and grading. This is often the cheapest item on the list and the one that changes the most.
A complete vapour barrier, covering the whole crawl space floor and lapped up the piers.
Ventilation or conditioning, depending on how the space is built.
Then, if anything remains, treatment — and by then usually less of it.
A company that quotes a treatment without walking the exterior has answered the wrong question. One that quotes drainage and a barrier is quoting the thing that keeps working after the spray stops.
What this means for you specifically
If you own and live in the home
The insects are the cheapest survey of your crawl space you will ever get.
Your action: get the moisture assessed and quoted before you buy any treatment, and ask specifically about the vapour barrier and where the downspouts go.
If you are selling
Conducive conditions appear on the wood-destroying insect report whether or not termites do, and a report noting standing water and a torn barrier invites a renegotiation.
The standard Northern Virginia contract obliges the seller to furnish a report dated within 90 days of settlement and to pay for treatment and repair of the damage the report identifies. Damp conditions are what turn a clean report into a report with findings.
Your action: deal with drainage before the inspection rather than after it. The contract clause →
If you are buying
The crawl space is the single most common area a report records as inaccessible, and it is where this evidence lives.
Your action: read the obstructions section first, and ask directly whether the crawl space was entered and what the humidity was. Reading the report →
If you rent
Drainage, vapour barrier and ventilation are the structure, and the structure is the landlord's through the habitability duty under § 55.1-1220. Your duty under § 55.1-1227 is prompt written notice.
Your action: report the water in writing, with photographs, rather than the insects. The water is the part that is unambiguously theirs. Step by step →
If you are a landlord
Repeated treatment of a wet crawl space is money spent annually on a problem that a one-off repair would end — and a record of repeat visits without a structural fix reads badly if the tenancy goes to a hearing.
Your action: have the moisture source identified in writing at the first visit, and fix the drainage. What you owe →
Before you call: what costs what
An inspection and a treatment are two separate services with separate prices, and here the useful money goes to neither — it goes to the repair.
| Typical Virginia range | What it produces | |
|---|---|---|
| General pest inspection | often free where the company expects to quote treatment | a verbal or written assessment |
| Wood-destroying insect inspection and report | $65–$200 | the NPMA-33, including conducive conditions |
| Perimeter treatment | quoted per property | a treatment record, and a temporary result |
| Drainage, vapour barrier, ventilation | quoted by a contractor | the thing that actually changes the reading |
What is usually free: a quote once someone has been under the house.
What is usually not: the inspection report used in a real estate transaction.
Ask which applies before you book, and ask for the moisture work to be quoted separately so you can compare it.
Common misunderstandings
"They're eating the house." None of these is a wood-destroying insect. What they indicate is the condition that invites one.
"Spray the perimeter each spring." An annual treatment for a permanent condition is an annual payment for a temporary result.
"Centipedes are the problem." Centipedes are eating the problem. Remove the damp and their food goes with it.
"Camel crickets are dangerous." They are startling and they chew fabric and paper. They do not bite meaningfully and they carry nothing of note.
"Sealing the crawl space vents will dry it out." Sometimes the opposite. A closed crawl space needs to be conditioned; closing vents without that can trap moisture.
"It's just a wet spring." A crawl space that dries between rains is fine. One that supports a population is not drying.
What to ask a pest control company
- What is the relative humidity under the house, and what did you measure it with?
- Is the vapour barrier complete, and can you photograph where it is not?
- Where do the downspouts discharge, and does the grading fall away from the building?
- Which of these findings would appear as conducive conditions on a wood-destroying insect report?
- What would you fix first if you were paying for it?
- Is the moisture work quoted separately from the treatment?
- Under what name is your Virginia pesticide business licence held?
The fourth question links this to the expensive problem, and a good inspector will answer it readily.
What to have ready before you call
Whether the house has a crawl space, a basement or a slab; whether there is a vapour barrier and its condition; where the downspouts discharge; whether water has ever stood under the house; which insects you are seeing and roughly how many; and your settlement date if you are under contract.
Frequently asked questions
Do I need to treat at all? Often not, once the space is dry. Treatment before drying is a payment for a result that expires.
How long after fixing the moisture do they go? Weeks rather than days. The existing population has to die off, and they die when the humidity falls.
Are silverfish a sign of something worse? They are a sign of humidity and starch. In a stored-paper area they are their own problem; elsewhere they read as damp.
Do camel crickets come from outside? Yes, from leaf litter and mulch against the foundation, through the same gaps that let in the damp.
Will a dehumidifier fix a crawl space? It can help a conditioned, sealed space. In a vented crawl space with water entering it, it runs continuously against the weather.
Verify before you pay anyone
VDACS publishes an updated list of licensed pesticide businesses weekly, with a public lookup confirming an active Pesticide Business License. General pest control is category 7a and wood-destroying pest control 7b under 2VAC5-685-70.
If the quote includes crawl space work rather than only treatment, ask who performs it and under what credential — encapsulation and drainage are contractor work, not pesticide application, and the two are frequently sold together by companies holding one of them. How to check →