Signs of Cellar Spider Infestation – and What a Large Population Actually Means
Cellar spiders are the thin, long-legged spiders that build loose, messy webs in garage corners, utility rooms, and basements across Collin County. Most people either ignore them or wipe down the webs every few weeks and call it done. But a large cellar spider population is a signal worth paying attention to – because what they eat tells you what else is in your home.
What Cellar Spiders Actually Are
The long-bodied cellar spider (Pholcus phalangioides) is one of the most common house spiders in North Texas. They are frequently mistaken for daddy long-legs, which is also a common name for harvestmen – a completely different arachnid with no venom glands at all. Cellar spiders are true spiders with venom, but their venom is very mild and their bite is nearly harmless to humans.
Identifying characteristics:
- Body and legs. Small gray or tan body (about 6-9mm) with legs that extend 2 to 3 inches in every direction. The leg length relative to body size is distinctive – no other common house spider has this proportion.
- Webs. They build irregular, three-dimensional cobwebs in corners and wall/ceiling junctions. Unlike orb weavers, cellar spider webs are not geometric – they look like tangled, chaotic masses that accumulate dust quickly.
- Vibrating behavior. When disturbed, cellar spiders shake rapidly in their web – a defensive behavior that makes them appear blurry and harder to grab. This is a reliable identification sign.
- Locations. Garage corners, HVAC closets, utility rooms, basements, crawl spaces, and the gaps behind water heaters. Anywhere dark, undisturbed, and with access to other insects.
Signs of a Cellar Spider Infestation
A single cellar spider in a garage corner is normal for homes in McKinney and across Frisco and Allen. A growing population across multiple locations is different. Signs the population has moved from incidental to established:
- Webs in multiple rooms. Finding cellar spider webs in more than one location – garage plus utility room plus basement – suggests they have spread through the structure rather than entered from one point.
- New webs rebuilding within days. Cellar spiders rebuild quickly when their webs are removed. If you clear webs in a corner and find new construction within 48 hours, the spider is still present and active in that spot.
- Visible egg sacs. Cellar spiders carry their egg sacs in their chelicerae (mouthparts), holding them until the eggs hatch. Seeing females carrying small, round egg masses is a sign of an active, reproducing population.
- Increasing numbers season to season. One or two per year is normal. If you are finding noticeably more than the previous spring, the population is growing – which means the food source supporting them is also growing.
Are Cellar Spiders Actually Dangerous?
The widespread claim that cellar spiders are “extremely venomous but cannot bite through human skin” is a myth. Cellar spiders can and occasionally do bite when handled, but their venom is weak and produces, at most, a mild, brief burning sensation. They are not medically significant. There is no documented case of a cellar spider bite causing serious harm to a healthy adult.
The real risk from a heavy cellar spider population is indirect: the webs accumulate quickly, coat surfaces in dust and debris, and become progressively harder to manage if the underlying pest population supporting them is not addressed. The spiders also leave behind insect carcasses and shed exoskeletons in and around their webs.
Cellar spiders are not a reason to panic, but they are a reason to look at what else is sharing your home with them.
What to Do About Cellar Spiders
Regular web removal keeps cellar spider populations manageable in lightly affected areas – a vacuum with an extension wand covers most garage and utility room corners quickly. Reducing humidity in basements and garages removes the moisture that supports both the cellar spiders and the insects they eat.
If web removal every few weeks is becoming a persistent chore, or if you are finding cellar spiders in living areas of the home rather than just utility spaces, the underlying pest population is worth addressing. Professional spider control targets the entry zones and the prey insect populations that sustain spider activity, which reduces the population more lastingly than surface treatment alone.
Spider webs taking over your garage? Same-day spider control in Collin County.
We find what the spiders are feeding on, treat the full pest population, and reduce activity at the source.