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Grass Spiders: Are They Dangerous and How to Get Rid of Them

Closeup shot of a grass spider on its web on a plant

The Grass Spider, scientifically known as Agelenopsis, is a common household arachnid found primarily in North America.

These spiders are easily identifiable by their funnel-shaped webs, which they spin in lawns, dense vegetation, and brush piles. The males, with their smaller body length, are often mistaken for spiderlings, while the females, larger specimens, are noted for their distinct carapace and abdomen markings.

Grass spiders have a unique mating process. The males approach females cautiously to avoid becoming prey, a common occurrence in the spider world. After mating, the females produce an egg sac, from which numerous spiderlings hatch, contributing to the late summer increase in spider sightings.

Despite their menacing appearance, grass spiders pose little threat to humans. Their small fangs can bite human skin, but the venom is not harmful, causing only minor swelling.

However, they play a significant role in controlling the insect population, including beetles, small butterflies, and moths, making them a beneficial presence in our habitat.

What is a Grass Spider?

Grass spiders, scientifically known as Agelenopsis, are a common spider species found throughout North America.

They are part of the Agelenidae family, known for their distinct funnel-shaped webs. These spiders are often found in lawns, shrubbery, dense vegetation, and brush piles, which serve as their primary habitat.

Grass spider on a web

Photo Credit: Shutterstock.

Grass spiders are known for their funnel web structures, which they weave in grass, between rocks, or in crevices. These webs are not sticky but act as a shelter and a trap for their prey, which includes small insects like beetles, small butterflies, and moths.

When a prey walks over the web, the vibration alerts the spider, which rushes out from the tunnel to capture and immobilize it with a venomous bite.

Lifecycle of a Grass Spider

The life of a grass spider begins in an egg sac, a protective casing woven by the female using her spinnerets, the silk-producing organs located at the end of her abdomen. Each sac contains hundreds of eggs, which overwinter or survive the winter, before hatching in late summer.

Upon hatching, the spiderlings, or young spiders, emerge. These tiny creatures, no larger than a speck of dew, will spend their early days close to their birthplace.

As they grow, they will venture further afield, spinning their own webs and hunting small insects, beetles, moths, and small butterflies for prey.

Male grass spiders are generally smaller in body length than females, but larger specimens can be found. The males can be distinguished by their carapace, or hard upper shell, and a thin skin covering their cephalothorax, the fused head and thorax section of their body.

One of the most critical stages in the lifecycle of the grass spider is mating. Males approach females with caution, as females are known to occasionally prey on their suitors.

After a successful mating, the female will produce another egg sac, and the cycle begins anew.

How to Identify Grass Spiders

Grass spiders are generally small to medium in size, with body lengths ranging from 10 to 20 millimeters.

The larger specimens are usually females, while the males are slightly smaller. They have a distinctive carapace, or hard upper shell, and a thin abdomen.

The cephalothorax, a fused head and thorax, is covered with a pattern of brown and black, which blends well with their habitat.

One of the key identifying features of the grass spider is the presence of spinnerets at the end of their abdomen. These are the organs that produce the silk for their webs.

Macro of a grass spider

Photo Credit: Shutterstock.

In the case of the grass spider, the spinnerets are quite long and visible, extending beyond the length of their abdomen.

The male grass spiders are recognizable by their enlarged pedipalps, which are used for mating. These look like small boxing gloves and are often mistaken for fangs.

The females, on the other hand, can be identified by their larger abdomen, especially during late summer when they carry eggs. The egg sac is carried by the female until the spiderlings are ready to hatch.

Grass spiders are mostly found in lawns, dense vegetation, brush piles, and shrubbery. They can also inhabit cracks in the wall or a rock crevice.

They are most active during the early morning when the dew highlights their webs, making them easier to spot.

Grass Spider vs Hobo Spider

Grass spiders are often mistaken for hobo spiders due to their similar appearance. However, hobo spiders are generally larger and have a more pronounced pattern on their abdomen.

Hobo Spider on a green leaf

Hobo Spider – Photo Credit: Shutterstock.

Plus, hobo spider bites can cause necrotic skin lesions, while grass spider bites, though rare, only cause mild swelling due to their small fangs and less potent venom.

Grass Spider vs Wolf Spider

Grass spiders and wolf spiders have similar appearances, especially in their head region.

Both spiders have two black lines running down both sides of a tan-colored midline, but the lines are less vivid in grass spiders compared to wolf spiders.

Wolf spider on a green leaf

Wolf Spider – Photo Credit: Shutterstock.

The abdomen of a wolf spider has a bold black line down the middle that comes to a point, which is absent in grass spiders.

Plus, grass spiders are known to be less aggressive than wolf spiders and are unlikely to bite.

Damage Caused by Grass Spider

The primary damage caused by these spiders is not usually of a physical nature but is more related to the inconvenience and fear they can instill.

One of the main issues with grass spiders is their habits and the environment they can attract.

They prefer to shelter in rock crevices, brush piles, and cracks in human dwellings. This can become a problem if their presence attracts other pests.

Webs of grass spider on the ground

Photo Credit: Shutterstock.

For instance, their leftover prey and egg sacs can attract beetles and other insects.

In addition, spiderlings overwinter, meaning they survive the winter season, and can emerge in large numbers in late summer. This can lead to a sudden infestation, which can be alarming and inconvenient for homeowners.

It’s also worth noting that pet food and food crumbs can attract these spiders. Therefore, maintaining cleanliness and avoiding leaving food out can help prevent an infestation.

Do Grass Spiders Bite? Are They Dangerous For Humans?

Grass spiders, or Agelenopsis, are a common sight in North America, especially in lawns, dense vegetation, and brush piles.

They are known for their distinctive funnel-shaped webs, which serve as both a shelter and a trap for their prey. Yet, many people often wonder, do these spiders bite? Are they a threat to humans?

It’s important to note that grass spiders are generally not aggressive towards humans. They are more likely to retreat into their tunnel in the web when disturbed.

However, they can bite if they feel threatened or cornered. The bite of a grass spider is usually a defensive action rather than a predatory one.

The bite of a grass spider is not venomous to humans. Unlike some other spiders, such as the notorious funnel web or hobo spiders, the venom of the grass spider doesn’t cause necrotic skin lesions.

Grass spider on white background

Photo Credit: Shutterstock.

The small fangs of the grass spider can penetrate thin skin, but the bite is usually no more severe than a bee sting. Symptoms can include mild swelling and discomfort at the site of the bite, but severe reactions are rare.

Nonetheless, it is crucial to clean the bite area thoroughly to prevent bacterial infections. This is because the fangs, while small, can still introduce bacteria from the spider’s environment into the human skin.

Top 4 Signs of Grass Spider Infestation

1. Unique Webs

One of the most obvious signs of a grass spider infestation is the presence of their unique webs. These are not the typical orb-shaped structures most people associate with spiders.

Instead, Agelenopsis creates a funnel web, which is a flat, horizontal web with a small tunnel at one end. This tunnel serves as a shelter for the spider and a trap for its prey.

If you notice these webs in your lawns, shrubbery, or dense vegetation, you may have a grass spider infestation.

Grass spider on its complex web

Photo Credit: Shutterstock.

2. Spotting the Spiders

The spiders themselves are another sign. Male grass spiders are usually smaller in body length than females, with the larger specimens reaching about 19mm.

Both males and females have a cephalothorax (a fused head and thorax) covered by a hard upper shell known as a carapace and an abdomen adorned with spinnerets at the end.

The males can be distinguished by their swollen palps, which they use for mating.

3. Finding Egg Sacs

Grass spiders lay their eggs in late summer or early fall. Females produce a silk egg sac, which they hide in safe places such as rock crevices, brush piles, or cracks in the wall.

These sacs overwinter and hatch in the spring, releasing numerous spiderlings.

If you find these egg sacs in or around your property, it’s a clear sign of a grass spider infestation.

4. Seeing Sticky Residue

Although grass spiders primarily feed on small insects like beetles, moths, and small butterflies, they can also be attracted to food crumbs and pet food left out in the open.

Regularly spotting spiders in your home or seeing a sticky residue, which could be leftover prey, are both signs of an infestation.

If you’re unsure about the type of spider infestation you’re dealing with, it’s best to consult a pest control professional.

How to Prevent Grass Spider

Grass spider on a stem

Photo Credit: Shutterstock.

Preventing grass spiders from taking shelter in your home or yard involves understanding their habitat and habits. Here are the three best ways to prevent an infestation:

  1. Maintain Your Lawn: Regularly mowing and removing brush piles can deter these spiders from making your yard their habitat. Also, removing any dew or sticky residue from your lawn can help, as grass spiders are attracted to these conditions.
  2. Seal Cracks and Crevices: Sealing cracks and crevices around your home can also prevent grass spiders from finding shelter. This includes the small fangs in the carapace, or hard upper shell, of the spider’s cephalothorax and abdomen. The spiders use their spinnerets to produce silk, which they use to construct their tunnel or funnel web.
  3. Keep Your Home Clean: Grass spiders, especially larger specimens, are attracted to food crumbs and pet food. Regularly cleaning up after meals and properly storing pet food can help prevent these spiders from entering your home.

How to Get Rid of Grass Spiders

While these spiders are not harmful to humans, their presence can be disconcertingly noticeable, especially in late summer when the males venture out in search of females for mating.

If you’re facing an infestation that’s disrupting your life, consider these following tactics to get rid of grass spiders:

Get Rid of Hiding Spots

One of the first steps to getting rid of grass spiders is understanding their habitat and habits. Grass spiders are attracted to areas that provide shelter and prey.

They feed on small insects such as beetlеs, small butterflies, and moths, caught in their webs.

They also have a preference for areas with dense vegetation or brush piles, as these provide the perfect environment for their funnel web homes.

Maintain Your Yard

Man cleaning dried leaves on the yard

Photo Credit: Shutterstock.

Maintaining a clean and tidy yard can help deter these spiders. Regularly mowing your lawn, trimming shrubbery, and removing brush piles can destroy their habitat and discourage them from settling in your yard.

Sealing cracks in the house’s exterior and clearing rock crevices can also limit their shelter options.

In addition, be sure to clean up any food crumbs or pet food left outside as these can attract insects, which in turn, attract spiders.

Last Resort: Insecticides

In some cases, you may need to resort to insecticides, especially if there’s a significant infestation.

However, it’s essential to remember that grass spiders, despite their somewhat alarming appearance, are beneficial predators that help control other pest populations.

Also, remember that spiders often overwinter in homes, finding refuge in the warm indoors. Regularly cleaning and vacuuming can help ensure that no unwanted eight-legged guests spend the winter in your home.

 

Other Spider Guides from Planet Natural:

The 11 Biggest Spiders In The World (And Where They Live)

Jumping Spider: Everything You Need to Know + 7 Facts!

Hobo Spider: Identification, Habits, and Effective Control Methods