Bugs and spiders in Delaware
Asian lady beetles, spotted lanternflies and eastern carpenter bees are the species most often recorded in Delaware, with bold jumping spiders and yellow garden spiders close behind. American and oriental cockroaches are both listed as Common here, and one mosquito, the yellow fever mosquito, is established only in parts of the state.
Get advice if bitten
These are found in Delaware. 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 Delaware
Established here or recorded often, most-recorded first.
Asian lady beetleBe carefulCommon · 2,247 records
Spotted lanternflyHarmlessEstablished · 1,183 records
Eastern carpenter beeBe carefulCommon · 792 records
Bold jumping spiderHarmlessCommon · 550 records
Yellow garden spiderBe carefulCommon · 539 records
Tan jumping spiderHarmlessCommon · 477 records
Brown marmorated stink bugHarmlessCommon · 381 records
Spotted orbweaverHarmlessCommon · 305 records
Lone star tickGet adviceEstablished · 242 records
Boxelder bugHarmlessCommon · 236 records
Dark fishing spiderBe carefulCommon · 228 records
Eastern yellowjacketBe carefulCommon · 206 records
Black carpenter antHarmlessCommon · 197 records
Greenhouse millipedeHarmlessCommon · 175 records
Pill bugHarmlessCommon · 148 records
Western conifer seed bugHarmlessCommon · 148 records
American dog tickGet adviceEstablished · 147 records
Greenhouse camel cricketHarmlessCommon · 147 records
European paper waspBe carefulCommon · 136 records
Odorous house antHarmlessCommon · 116 records
House centipedeBe carefulCommon · 92 records
Woodlouse spiderHarmlessCommon · 82 records
Northern black widowGet adviceEstablished · 80 records
Pavement antHarmlessCommon · 80 records
European earwigHarmlessCommon · 78 records
Broad-faced sac spiderBe carefulCommon · 77 records
Varied carpet beetleHarmlessCommon · 72 records
Blacklegged tickGet adviceEstablished · 52 records
Oriental cockroachBe carefulCommon · 33 records
American cockroachBe carefulCommon · 29 records
Long-bodied cellar spiderHarmlessCommon · 27 records
Common house spiderHarmlessCommon · 25 records
House mosquitoBe carefulEstablished · 3 records
Brown dog tickGet adviceEstablished
Yellow fever mosquitoBe carefulEstablished (parts of the state)What to watch for in Delaware
Ticks matter most in Delaware. The lone star tick is the most-recorded of the established ticks here, ahead of the American dog tick and the blacklegged tick, and the brown dog tick is established too. The lone star tick can spread ehrlichiosis, and its bites are linked to alpha-gal syndrome, a red-meat allergy. The blacklegged tick can spread Lyme disease and other serious infections. Check yourself and pets after time outdoors, and watch for fever or rash after any bite.
The northern black widow is established in Delaware. If you suspect a bite from an adult female, get medical advice right away, since the pain can spread and muscle cramps can follow, and call Poison Help at 1-800-222-1222 if you are worried. The southern black widow has many records here but is not known to live in the state, and those sightings are often misidentifications or hitchhikers. Yellowjackets, European paper wasps, and eastern carpenter bees are the stinging insects to watch around the house.
Through the year
- Spring
- Lone star tick adults are most active April through June, and eastern carpenter bees are drilling and hovering around the house.
- Summer
- Lone star tick nymphs are out from May into August, spotted lanternflies reach the adult stage in July, and American cockroaches are seen most in the warm months.
- Fall
- Boxelder bugs, brown marmorated stink bugs and Asian lady beetles crowd onto sunny walls and windows in autumn, and yellow garden spiders are most noticeable in late summer and early fall.
- Winter
- A few stink bugs and boxelder bugs wake on mild days, greenhouse camel crickets linger in damp basements, and house centipedes are around all year.
Seen now and then
Recorded a few times; often brought in on plants, firewood or luggage.
Indianmeal mothHarmlessOccasional · 21 records
Zebra jumping spiderHarmlessOccasional · 15 records
Northern yellow sac spiderBe carefulOccasional · 12 records
German cockroachBe carefulOccasional · 9 records
False black widowBe carefulOccasional · 8 records
Barn funnel weaverHarmlessOccasional · 8 records
Fruit flyHarmlessOccasional · 6 records
SilverfishHarmlessOccasional · 5 records
House flyBe carefulOccasional · 3 recordsRecorded, not established
Range maps don't place these here, but people have recorded them. Usually hitchhikers.
Lists come from research-grade iNaturalist sightings (Delaware: 130,873 arthropod records) and, for dangerous species, published range maps. A species with few records may be a hitchhiker. Counts pulled Oct 18, 2026.

