Grass spiders, scientifically known as Agelenopsis, are common arachnids often found in North American yards and gardens. Known for their distinctive funnel-shaped webs, these spiders play a vital role in controlling insect populations. This article delves into the diet of grass spiders, exploring what they eat, how they hunt, and other interesting facts about their feeding habits.
What Grass Spiders Look Like
Grass spiders are often yellow, brown, or cream-colored. They have two dark brownish bands running lengthwise across their cephalothorax and abdomen. Their eyes are arranged in three rows, with two on top, four in the middle, and two on the bottom.
Identifying Grass Spiders
Grass spiders are medium-sized, with a body length ranging from 0.3 to 0.75 inches (1 to 2 cm). They are frequently mistaken for wolf spiders or hobo spiders, but there are key differences. Unlike wolf spiders, grass spiders have a visible spinneret at the end of their abdomen, which they use for web-making. The patterns on their head region can also help differentiate them; grass spiders have two black lines on either side of the midline, which are slightly lighter and thinner than those on a wolf spider. Additionally, the abdomen of the grass spider features a series of dark chevrons, which are lighter than those found on wolf spiders.
Grass spiders have a hard shell or carapace that is round in shape and has three distinct bands. Two of them run on either side of the middle band and are darkish brown in color. The grass spider is usually yellowish brown in color with chevron patterns that distinguish them from other similar spiders. But they show a mix of different colors on their body. The carapace is yellowish brown in color while the abdomen and the distinct part of the legs are relatively darker in color.
Habitat and Web Construction
Native to North America, grass spiders are found throughout natural and manmade habitats, preferring grasslands and forests, but they are also commonly seen in lawns. Grass spiders are very common in Pennsylvania. The webs of grass spiders can make a yard appear shabby and neglected.
Read also: Spider Beetle Identification
The grass spider's web is more often noticed than the spider itself. The web is sheetlike, usually positioned horizontally, with a funnel leading downward to a shelter such as a rock crevice or dense vegetation. The web may be up to three feet wide, and the funnel portion over a foot long.
The webs, which are large, somewhat concave, mostly horizontal, and sheetlike with a funnel or tunnel located off to one side, are often observed more frequently than the spiders themselves. The webs are found on grass, weeds, and ground covers such as ivy, pachysandra, or periwinkle, and in numerous exterior places such as fencerows, bushes, and brush piles.
Dietary Preferences of Grass Spiders
Grass spiders are carnivorous and primarily insectivorous, meaning their diet consists mainly of insects. As hunters, grass spiders help control the population of prey insects found in the grass.
Common Prey
The diet of grass spiders includes:
- Moths
- Beetles
- Crickets
- Aphids
- Grasshoppers
- Ants
- Small butterflies
They eat insects that are smaller than them.
Read also: Diet of the Brown Recluse Spider
Hunting Techniques
Grass spiders are funnel web weavers. These spiders construct their webs in lawns and other places that enable the web to be used for protection and the funnel trap to capture prey. When prey is captured, these spiders drag their prey into the funnel of the web.
Unlike orb weavers, grass spiders do not rely on sticky silk. Instead, their webs are non-sticky but highly effective at entangling prey. The shape of the web helps to trap insects, which then fall inside. Because of the shape, the prey falls inside the trap. This is why grass spiders are agile. When an insect lands on the web, the vibrations alert the spider, which quickly emerges from its funnel to capture its prey.
The web of grass spiders is not sticky, and it can be amusing to tap gently with a twig on the surface of the web, prompting the spider to rush out of her tunnel.
Grass Spider Life Cycle
Grass spiders do not live as long as many other spiders and their natural lifespan is only about one year. The male grass spider lives for only about 2-3 weeks after mating. The female grass spider deposits her egg sac in the late winter and dies shortly after laying the eggs.
The life cycle of a grass spider begins when the female lays her eggs in a silk egg sac, which she hides in dense vegetation or under brush piles. The female deposits a lens-shaped, white egg sac in the late summer to fall. The eggs hatch in the spring, and after a series of molts, the immatures become adults in late summer. Grass spiders grow through several molts, shedding their thin skin as they mature. Male grass spiders roam in search of mates during the breeding season, while females remain near their webs to protect their egg sacs.
Read also: Diet of Argiope aurantia
Behavior and Habitat
A grass spider is solitary in nature. You will not find it interacting with other of its species socially unless it is the mating season. But one grass spider may share its habitat with other grass spiders sometimes. Their behavior is mostly nocturnal where they avoid going out to hunt in the daylight to hide from predators.
Grass spiders mainly reside in North America. But they were introduced into various countries in Central Asia. If you wish to spot them, you can find them in dirty places in a house. They are not attracted to grime, but this is where their prey resides. Many small insects like ants are usually near food scraps or other dirty areas. However, this is only a rare instance where a male grass spider may find itself in homes. Otherwise, they are found in lawns, grass, gardens, ornamental plants and trees, along foundations, log piles, under rocks and lawn ornaments, tubs, window wells, and sinks.
In urban environments, grass spiders may seek shelter in sheds, garages or homes, often drawn to areas with pet food or insects.
Grass Spiders and Humans
Grass Spiders are not particularly dangerous to humans. They carry venom, but that is mostly for their prey. Moreover, they are very shy and not at all aggressive in nature. Grass spiders are not aggressive, but they may bite humans if they feel threatened. Reported grass spider bites have caused pain, swelling, redness, and itching. These symptoms usually stay with the victim for a time ranging anywhere between one day and ten days. Sometimes, a bacterial infection may occur.
Having said that, they may sometimes inhabit domestic homes. You might only find them due to their webs because they stay hidden in the funnel portion of the web that is situated within a shelter. But if you have small insects, you may find yourself encountering a grass spider infestation too. Clean up leftover food, pet food, crumbs, and scraps around the house.
Distinguishing Features
Besides their distinctive webs, grass spiders can be identified by their greatly elongated hind spinnerets and the dorsal markings on the carapace and abdomen. Females are from 10 to 20 millimeters and the males from 9 to 18 millimeters in length. The carapace is yellow-brown to brown with a pair of darker longitudinal bands extending back from the lateral eyes, and another pair of very thin lines located one on each side of the carapace. The abdomen is generally darker than the carapace and has a lighter median band, sometimes with a scalloped edge.
Taxonomy
Grass spiders are known as the Agelenopsis by scientists. It was first described in 1869 and is Greek in origin. The term Agelenopsis consists of “Agelena”, which is a genus also known as Eurasian grass spiders, and “opsis”, which means “to look like”.
There are 14 species in genus Agelenopsis in North America north of Mexico. Three common species in Missouri are:
- Eastern funnelweb spider (Agelenopsis naevia)
- Pennsylvania funnelweb spider (A. pennsylvanica)
- Emerton’s funnelweb spider (A. emertoni)
Their similar color patterns make them difficult to distinguish.