Yellow sac spiders measure 1/4 to 5/16 inch long (adult body) and with legs extended, can reach across a quarter-sized coin. They are light yellow to pale green with brown chelicerae and pedipalp tips. The eyes are dark brown to black, equal-sized, and are arranged in two rows of 4. Young are produced in June and July.
These spiders are sometimes called yellow house spiders. Yellow sac spiders are active hunters and nocturnal. They readily enter structures and are active indoors all year round. Persons may be bitten in their sleep if their unconscious movements threaten harm to a spider that is wandering across bedding, sleepwear or the skin.
Spiders in their silk retreats in recessed areas among folds of draperies, appliance and faucet handles, etc. may deliver defensive bites when persons grasp these sites with their hands. In most cases, yellow sac spider bites result in brief, local pain (e.g., pin-prick) and short-term soreness or sensitivity to touch. A mosquito bite-like welt may result.
Like all spiders, cellar spiders are predators that will kill and eat almost any insect.
What you can do: The likelihood of introducing spiders within structures and encountering them in and around buildings can be reduced by:
- Eliminating tall and dense vegetation close to the foundation which serve as harborage for spiders and their prey (e.g., vines, groundcover, juniper, uncut grass and weeds),
- Excluding gaps under doors (by replacing or adding door sweeps), lower courses of siding, around utility penetrations and weep holes in brick veneer,
- Capturing wandering spiders on ground level, in basements and in attached garages by placing sticky traps indoors along walls behind furniture, washer, dryer, sump pump, water heater, furnace, commode, and storage (out of reach of children and pets), and
- Removal using a shop vacuum cleaner or household vacuum fitted with a hose attachment; this is useful for removing spider webs as well.
A Quik-Kill service technician will apply an exterior barrier treatment around the foundation perimeter, beneath lower siding, under eaves and porticos, along exterior molding/trim, thresholds, patio, deck and chimney attachments, as well as inside and around sheds and other outbuildings.
A regular pest management service program may be required in cases where large populations of spiders are present and where landscaping conditions and locality are conducive to their propagation. Indoors, basement sillplates and perimeters, as well as the corners and edges of spider-infested rooms, can be treated.
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