Bug Category: Spiders

Wolf Spider

Summary

Wolf spiders are usually large, hairy spiders that are not associated with webs. They look much worse than they are.

Wolf spiders are members of the family Lycosidae, from the Ancient Greek word “λύκος” meaning “wolf”. They are robust and agile hunters with good eyesight. They live mostly solitary lives and hunt alone. Some are opportunistic hunters pouncing upon prey as they find it or even chasing it over short distances. Some will wait for passing prey in or near the mouth of a burrow.

Wolf spiders resemble Nursery web spiders (family Pisauridae), but they carry their egg sacs by attaching them to their spinnerets (Pisauridae carry their egg sacs with their chelicerae and pedipalps). Two of the Wolf spider’s eight eyes are large and prominent, which distinguishes them from the Nursery web spiders whose eyes are all of approximately equal size.

There are many genera of wolf spider, ranging in body size from less than 1 to 30 millimetres (0.04 to 1.18 in). They have eight eyes arranged in three rows. The bottom row consists of four small eyes, the middle row has two very large eyes (which distinguishes them from the Pisauridae), and the top row has two medium-sized eyes. They depend on their excellent eyesight to hunt. They also possess an acute sense of touch.

Their eyes reflect light well, allowing someone with a flashlight to easily hunt for them at night. Flashing a beam of light over the spider will produce eyeshine. The light from the flashlight has been reflected from the spider’s eyes directly back toward its source, producing a “glow” that is easily noticed. This is also especially helpful because the wolf spiders are nocturnal and will be out hunting for food, making it easier to find them.

Wolf spiders are unique in the way that they carry their eggs. The egg sac, a round silken globe, is attached to the spinnerets at the end of the abdomen, allowing the spider to carry her unborn young with her. The abdomen must be held in a raised position to keep the egg case from dragging on the ground, however despite this handicap they are still capable of hunting. Another aspect unique to wolf spiders is their method of infant care. Immediately after the spiderlings emerge from their protective silken case, they clamber up their mother’s legs and crowd onto her abdomen.

Because they depend on camouflage for protection, they do not have the flashy appearance of some other kinds of spiders. In general their coloration is appropriate to their favorite habitat.

Hogna is the genus with the largest of the wolf spiders. Among the Hogna species in the U.S., the nearly solid dark brown Carolina wolf spider (H. carolinensis) is the largest, with a body that can be more than one inch long. It is sometimes confused with H. helluo, which is somewhat smaller and entirely different in coloration.

Some members of the Lycosidae, such as H. carolinensis, make deep tubular burrows in which they lurk most of the time. Others, such as H. helluo, seek shelter under rocks and other shelters as nature may provide. They may wander from place to place, and are therefore more likely to be the ones attracted into human habitation when the weather starts to turn colder in autumn.

There are many smaller wolf spiders. They live in pastures and fields and are an important natural control for harmful insects.

Toxicity

Wolf spiders are capable of defensive bites, and some South American species may give bites that are medically significant. However, in general their presence works in favor of humans because they consume insects.

Wolf spiders will inject venom freely if continually provoked. Symptoms of their venomous bite include swelling, mild pain and itching. Though usually considered harmless to humans, the bite of some species may be painful.

Habitat

Common household pests in the fall when they are looking for a warm place for winter; found around doors, windows, house plants, basements and garages.

Wolf spiders can be found in a wide range of habitats both coastal and inland. These include shrublands, woodland, wet coastal forest, alpine meadows, and suburban gardens. Spiderlings disperse aerially and consequently wolf spiders have wide distributions. Although some species have very specific microhabitat needs (such as stream-side gravel beds or mountain herb-fields) most are wanderers without permanent homes. Some build burrows which can be opened or have a trapdoor. Arid zone species construct turrets or plug their holes with leaves and pebbles during the rainy season to protect themselves from flood waters.

Pest Control

Spider control is best done on a one-to-one, as needed basis. A general spray for spiders is not recommended, unless the infestation seems severe. Tolerate what you can and spray with an aerosol what you can’t.

Yellow Sac Spider

Summary

Yellow Sac Spiders are relatively small (10 mm body length), and are yellowish in color; they are difficult to distinguish from one another.

Habits

Some yellow sac spiders are attracted to the smell of hydrogen oxide in gasoline. An unusual double pipe configuration in the Mazda6 led to a recall of around 65,000 Mazda6 vehicles in the U.S, Canada, Mexico and Puerto Rico from the 2009-10 model years after it was found that yellow sac spiders were building nests in the fuel line of the vehicles.

Habitat

In the autumn the food is disappearing so the yellow sac spider seeks indoor refuge to find food. Indoors it is often seen on walls and around different constructions. If disturbed it drops to the floor. Egg sacs are laid in corners of all sorts. The egg sacs are white and spun with silk. The female may guard her egg sac one way or the other, so be careful when removing egg sacs from around your home.

During the summer when there’s plenty of food the yellow sack spider prefers to live on trees, shrubs, and in low vegetation close to open expanses, such as fields. Occasionally it is found in cotton crops.

Threats

Bites generally produce instant, intense stinging pain, not unlike that of the sting of a wasp or hornet. This may be followed by localized redness, swelling and itching; these manifestations may or may not evolve into a necrotic lesion, but when that occurs healing is usually complete within eight weeks. Side effects may include chills, fever, headache, dizziness, nausea, anorexia, and sometimes shock.

Prevention

To protect your house from yellow sac spiders you can install tight fitting screens on windows and doors. You can also seal any crack or crevice a spider can fit into or get access to your house through. Installing yellow light on your front and back porch might also attract fewer insects, which are food for most if not all spiders.

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