Notable concerns
- Northern black widow (rare)
Medically significant species in Massachusetts
| Species | Scientific | Significance | Range note |
|---|---|---|---|
| Yellow Sac Spider | Cheiracanthium inclusum | Moderate | Throughout the continental United States and southern Canada. |
| Northern Black Widow | Latrodectus variolus | Medically significant | Eastern North America from southern Canada through New England and the Appalachian region |
All documented species in this index
Species below are present in Massachusetts according to extension publications and the rangeStates records in our species index. Click through for full profiles.
- Yellow Sac Spider - Cheiracanthium inclusum (Moderate)
- Northern Black Widow - Latrodectus variolus (Medically significant)
- Common House Spider - Parasteatoda tepidariorum (Low)
- Wolf Spider - Lycosidae (family overview) (Low)
- Cellar Spider - Pholcus phalangioides (Not medically significant)
- Bold Jumping Spider - Phidippus audax (Low)
- Yellow Garden Spider - Argiope aurantia (Not medically significant)
- Grass Spider - Agelenopsis spp. (Not medically significant)
Seasonal activity in Massachusetts
Spider activity in Massachusetts follows the documented peak season of May–September. Indoor sightings often spike in late summer and early fall as males wander to find mates and as cooling outdoor temperatures push synanthropic species toward heated structures.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Highlighted months reflect the state extension peak-activity window. Individual species (especially indoor recluse populations) may be active outside this range.
Prevention checklist for Massachusetts homes
- Seal exterior gaps wider than 1/8 inch around utility penetrations, dryer vents, and weep holes. Install door sweeps on garage and basement entries.
- Reduce harborage by storing firewood, lumber, and seldom-used boxes off the ground and at least 18 inches from foundation walls.
- For widow-active areas, wear gloves when handling outdoor electrical boxes, irrigation valves, and stacked materials. Widows favor undisturbed voids.
- Vacuum webs, egg sacs, and spiders rather than spraying. Mechanical removal outperforms most over-the-counter residual sprays for synanthropic species.
If you are bitten
Nearby states in the Northeast region
- Spiders of Connecticut - peak activity may–september
- Spiders of Maine - peak activity june–august
- Spiders of New Hampshire - peak activity june–august
- Spiders of New York - peak activity may–september
- Spiders of Rhode Island - peak activity june–august
- Spiders of Vermont - peak activity june–august
Sources
- [1]UMass spider identification - UMass Cooperative Extension. Accessed 2026-06-14.
- [2]Spiders and scorpions submitted as suspected brown recluse - Vetter RS, 2008. Accessed 2026-06-14.