Bugs and spiders in Wisconsin

Wisconsin records are led by Asian lady beetles, ahead of boxelder bugs, bold jumping spiders and European paper wasps. The state has a strong tick presence and only one Get-advice spider, the northern black widow. Fall invaders such as brown marmorated stink bugs and western conifer seed bugs are common too. The spotted lanternfly has been recorded but is not known to be established.

Get advice if bitten

These are found in Wisconsin. If you think one bit or stung you, call Poison Help at 1-800-222-1222; call 911 for trouble breathing or swelling.

Common in Wisconsin

Established here or recorded often, most-recorded first.

Asian lady beetleBe carefulCommon · 5,425 recordsBoxelder bugHarmlessCommon · 1,779 recordsBold jumping spiderHarmlessCommon · 1,658 recordsEuropean paper waspBe carefulCommon · 1,607 recordsYellow garden spiderBe carefulCommon · 1,497 recordsBrown marmorated stink bugHarmlessCommon · 1,326 recordsWestern conifer seed bugHarmlessCommon · 1,245 recordsBlack carpenter antHarmlessCommon · 1,123 recordsZebra jumping spiderHarmlessCommon · 1,045 recordsAmerican dog tickGet adviceEstablished · 1,013 recordsEastern yellowjacketBe carefulCommon · 886 recordsDark fishing spiderBe carefulCommon · 775 recordsEastern carpenter beeBe carefulCommon · 763 recordsGreenhouse millipedeHarmlessCommon · 753 recordsPill bugHarmlessCommon · 736 recordsTan jumping spiderHarmlessCommon · 707 recordsBlacklegged tickGet adviceEstablished · 501 recordsSpotted orbweaverHarmlessCommon · 346 recordsHouse centipedeBe carefulCommon · 337 recordsPavement antHarmlessCommon · 302 recordsWoodlouse spiderHarmlessCommon · 288 recordsEuropean earwigHarmlessCommon · 284 recordsOdorous house antHarmlessCommon · 209 recordsBroad-faced sac spiderBe carefulCommon · 176 recordsLong-bodied cellar spiderHarmlessCommon · 117 recordsIndianmeal mothHarmlessCommon · 83 recordsBarn funnel weaverHarmlessCommon · 82 recordsNorthern black widowGet adviceEstablished · 69 recordsNorthern yellow sac spiderBe carefulCommon · 61 recordsCommon house spiderHarmlessCommon · 35 recordsAmerican cockroachBe carefulCommon · 32 recordsSilverfishHarmlessCommon · 32 recordsLone star tickGet adviceEstablished · 20 recordsBrown dog tickGet adviceEstablishedHouse mosquitoBe carefulEstablished

What to watch for in Wisconsin

The American dog tick and the blacklegged tick are both established and heavily recorded. The blacklegged tick can spread Lyme disease and other infections, so remove it promptly and watch for rash or fever in the weeks after a bite. The lone star tick is listed as established but is recorded far less often. Brown dog ticks, which feed mostly on dogs, are listed too.

The northern black widow is established, and the only widow that lives here. A bite from an adult female can cause spreading pain and muscle cramps, so get medical advice if you think you were bitten, or call Poison Help (1-800-222-1222). Among Be-careful species, European paper wasps, yellow garden spiders and eastern yellowjackets are the ones most often met.

Through the year

Spring
Eastern carpenter bees are active in April, black carpenter ant swarmers appear in March through June, and overwintered boxelder bugs move around.
Summer
European paper wasps work around the outside of the house, greenhouse millipedes appear after heavy rain, and yellowjacket nests grow.
Fall
Boxelder bugs begin moving in during late August, followed by stink bugs and conifer seed bugs in September and Asian lady beetles in October.
Winter
House centipedes can be found indoors, and Indianmeal moths are most noticed between November and February.

Seen now and then

Recorded a few times; often brought in on plants, firewood or luggage.

Recorded, not established

Range maps don't place these here, but people have recorded them. Usually hitchhikers.

Lists come from research-grade iNaturalist sightings (Wisconsin: 430,293 arthropod records) and, for dangerous species, published range maps. A species with few records may be a hitchhiker. Counts pulled Oct 18, 2026.

Identify a bug in Wisconsin