Central Iowa Pest Guide
Iowa House Spiders: What They Are and How to Keep Them Out
Nearly every Des Moines home has spiders. The vast majority are harmless species that follow their food supply, so spider control is mostly insect control plus exclusion.
What Are Spiders?
The spiders found indoors in central Iowa are usually cellar spiders, funnel weavers (grass spiders), common house spiders, sac spiders, jumping spiders, and wolf spiders. All are predators that hunt other insects.
Iowa has very few medically significant spiders. Brown recluse populations exist in parts of the state but are uncommon in the Des Moines metro, and black widows are rare. Most suspected bites turn out to be other skin conditions.
Wolf spiders are large, fast, ground-hunting spiders that wander indoors in fall. They look alarming and are not dangerous.
Signs of Spiders in Your Home
- Irregular cobwebs in corners, basements, and window wells
- Funnel-shaped webs in shrubs, grass, and along foundations
- Egg sacs — small silk spheres — attached to webs or tucked in crevices
- Concentrations near exterior lights, where insect prey gathers
Why Spiders Matter
Spiders are mostly beneficial, but webbing is a nuisance, some species bite defensively when trapped against skin, and a heavy indoor population signals plenty of other insects to eat.
When Spiders Are Active in Central Iowa
Spider sightings peak in late summer and fall in central Iowa, when the year's spiders reach adult size and males wander in search of mates. Cellar spiders persist in basements all winter.
Home Remedies & DIY Control
- 1Vacuum webs, spiders, and egg sacs weekly, and empty the canister or bag outside. This is the single most effective home remedy.
- 2Reduce the prey supply: switch exterior lights to yellow bug bulbs or LEDs, and keep porch lights off when not needed so fewer insects gather.
- 3Seal cracks around foundations, windows, doors, and utility penetrations, and repair torn window screens.
- 4Cut back shrubs, ivy, and tall grass from the foundation and remove leaf litter and wood piles where spiders hunt.
- 5Reduce clutter in basements, closets, and garages. Store items in sealed plastic bins rather than cardboard.
- 6Sweep or hose down exterior eaves, soffits, and window wells each month during the warm season.
- 7Shake out stored shoes, gloves, and firewood before use to avoid defensive bites.
When to Call a Professional
Call a professional if you see repeated spiders you believe may be brown recluse, if webbing returns constantly despite cleaning, or if the underlying insect population needs a treated exterior barrier.
Voice calls only — this line does not receive text messages
Government & University Sources
- Iowa State University Extension — Spiders
- University of Nebraska–Lincoln Extension — Spiders
- CDC/NIOSH — Venomous Spiders
- U.S. EPA — Introduction to Integrated Pest Management
This article is general educational information for central Iowa homeowners, not professional, medical, or legal advice. Always read and follow pesticide label directions.