Black Widow spiders are widely known for their distinctive appearance and potent venom. While many associate these arachnids with warmer, southern climates, their range extends further north than many people realize, including Massachusetts. Understanding the specific species present and their habitats is important for residents.
Confirming Their Presence in Massachusetts
Black Widow spiders are found in Massachusetts, but their presence is sparse and predominantly limited to one species. The species established in the state is the Northern Black Widow, scientifically known as Latrodectus variolus. This species’ range extends from northern Florida up into southeastern Canada, making Massachusetts part of its natural, northern distribution.
Reports indicate that this species is uncommon in the state, making encounters infrequent for the average resident. While the Southern Black Widow (Latrodectus mactans) is the more widely recognized relative, the Northern Black Widow is the one confirmed to be native to the region. These spiders are most likely to be observed during the warmer months of spring and summer when they are active.
Where They Are Found and Habitat
The Northern Black Widow prefers secluded, undisturbed environments that offer both shelter and opportunities to build its characteristic tangled web. In Massachusetts, preferred outdoor habitats include areas with natural debris, such as woodpiles, stone walls, and hollow logs. They construct their webs in dark crevices and corners, often near the ground, where they can capture crawling insects.
While primarily outdoor spiders, they can occasionally be found near human structures that mimic their natural conditions, like sheds, garages, and crawl spaces. They are non-aggressive, typically only biting when accidentally disturbed or pressed against the skin. Encounters are rare because they seek out hidden spots away from activity, making accidental contact the most likely scenario for a bite.
Identifying the Species
The adult female Northern Black Widow is the most recognizable form of this spider. She is a medium-sized spider with a glossy, jet-black body and a globular abdomen. The most distinguishing feature is the red or orange marking found on the underside of the abdomen.
For Latrodectus variolus, this red marking, often referred to as an hourglass, is typically broken or separated into two distinct, triangular spots. This feature helps differentiate it from the Southern Black Widow, which usually has a complete, connected hourglass shape. Additionally, the Northern Black Widow female may have a row of red spots down the middle of the top side of the abdomen. Males and juvenile females are smaller and often display more vibrant colors with white or red stripes, but they are not considered dangerous to humans.