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Spined Micrathena

Micrathena gracilis[3]

The spined micrathena is a small orbweaver with a spiny, pyramid-like abdomen whose webs often stretch across woodland trails and yard openings in late summer; it is not known to bite people.[1][2]

Group
Arachnid
Order
Araneae
Family
Araneidae
US records
33 states
Sources
3 cited
Updated
2026-10-15
Female spined micrathena spider with a spiny, mottled abdomen hanging in its web
Female spined micrathena spider with a spiny, mottled abdomen hanging in its web. (c) Ken Clark, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • Females are about 3/8 inch long with a chunky abdomen bearing five pairs of black spines; color ranges from mostly black with white markings to whitish or yellowish mottled with black or brown.[1][2]
  • Males are much smaller (about 1/8 inch), lack spines and don't spin webs.[2]

Look-alikes

Look-alikeHow to tell them apart
Other micrathenas and the arrowhead spiderMissouri has two other micrathenas (arrowshaped and white) and the similar arrowhead spider; females are easily told apart by comparing photos.[2]

Where it lives

Found in most states east of the Rocky Mountains in wooded areas, including landscaped yards.[1][2]

US map: public records from 33 states since 1990 (GBIF).

Biology and life cycle

It overwinters as eggs; adults mature in early summer and females are found until October, most often in August and September.[1][2]

Webs are built across flyways and trails between bushes and trees, catching small flies such as gnats and mosquitoes.[1][2]

Damage and signs

  • It does no damage and almost never enters houses.[2]

Health risk

Penn State says it is not known to bite people and is probably not medically important.[1]

Control

Prevention

No control is needed; it is harmless and catches small flying insects.[1][2]

Common questions

What is the spiky spider in the web across the trail?
Likely a female spined micrathena.[1][2]
Does the spined micrathena bite?
It is not known to bite people.[1]
Will it come in the house?
Almost never.[2]

Sources

  1. Penn State Extension, “Spined Micrathena.” extension.psu.edu/spined-micrathena/ (accessed 2026-10-15)
  2. Missouri Department of Conservation, “Spined Micrathena (Field Guide).” mdc.mo.gov/discover-nature/field-guide/spined-micrathena (accessed 2026-10-15)
  3. iNaturalist, “Micrathena gracilis taxon page (order and family).” www.inaturalist.org/taxa/85333 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.