Agelenidae is a large family of spiders that include funnel weavers and the medically significant species known as the hobo spider (Eratigena agrestis). Agelenopsis is a genus of funnel web spiders that are commonly known as “grass spider” due to their habit of dwelling in grassy fields, residential turf grass, and anywhere where grass and foliage are prevalent. Grass spiders are very abundant in the northeast, and they are well known for being one of the most commonly encountered spider species within homes.
According to an online collection of user submitted photographs of spider species that are found within homes and in the wild, documented grass spider sightings have occurred twice as often within homes than outdoors. Also, according to a recent survey of pest management professionals throughout the US, grass spiders were the fifth most commonly controlled spiders within homes during 2016, making grass spiders more common within homes than yellow sac spiders and hobo spiders, and almost as common as brown recluse spiders.
Like all funnel weaver spiders, grass spiders are known for constantly building medium to large sized sheet webs, which are commonly found horizontally situated on grass, plants, hedgerows, weeds, bushes, patios, fencerows, and brush piles. Within homes, these spiders build sheet webs in cluttered areas like storage rooms, basements and attics, as well as in the corners of living rooms, bathrooms, and bedrooms. Humans encounter these webs more frequently than grass spiders themselves, and although the webs are not sticky, they are still effective for capturing prey. Grass spider webs are designed like a sheet, causing flies and other winged prey to run into them midflight and fall to the ground where they are immediately consumed by the super fast spiders.
Grass spiders have alarmingly large bodies and long legs that are both covered in brownish-grey hairs. They have an elongated abdomen, and two distinct black bands can be seen running vertically down their carapace, which is the firm portion of the upper body. Not counting their long legs, females average slightly more than ¾ of an inch in length, and males are comparable in size. Grass spiders are extremely fast, and they are generally shy around humans, but they are known for inflicting painful bites that are not considered medically significant. In Massachusetts, these spiders can be found indoors during the summer, and especially the fall when dropping temperature motivates the arachnids to seek warm shelter within homes.
Have you ever encountered grass spiders or their webs within your home?