Hobo Spiders 101

Scientific Name: Tegenaria agrestis

Why call them hobos? Because they hitched a ride some time ago and settled in America. Hobo spiders are native in Europe. They didn’t come to America through Ellis Island or the Port of New York. They landed in Seattle.

Maybe hobo spiders came to Seattle as eggs; maybe just one sac of eggs attached to one pallet. More likely, thousands of egg sacs on hundreds of pallets. Or maybe, a nest of the spiders. In any event they have spread from the Port of Seattle through almost all of Washington, Oregon, Idaho, and into Utah. These partially documented aliens can’t be deported and they appear to have social security.

Where Hobo Spiders Live

In Europe hobo spiders are found in the fields, seldom in houses. In America they have become urban dwellers, an interesting adaptation. However, the American experience is not fully indoors. Here hobo spiders commonly are found in gardens and yards, as well as near house foundations and basements.

What do Hobo Spiders Look Like?

Hobo spiders are large. The body, thorax and abdomen, may be one half inch or more. The long legs extend so that the spider would encompass a silver dollar. The legs have a light color and the body is a little darker.

How Big are Hobo Spiders?

The average size of a mature Hobo Spider is approximately 1/2 to 3/4 of an inch, with a leg span of 1.5 inches.

Hobo Spider Webs

Classified as funnel web weavers, hobo spiders weave a layered web which has a funnel-like lair at the rear where the spider waits for its prey. The web is not sticky, but is a “trip web” which traps the insect prey that is unable cope with the surface. The funnel web weavers, including the hobo spider are noted for rapid movement. When the web shakes, they get to the prey quickly.

Hobo Spider Bites and Effects

Why Hobo Spiders Bite

The eyesight of hobo spiders may not be keen. The spider won’t be able to distinguish among humans well enough to know they may not need to be on the defensive. In other words, the hobo spider will assume he is being attacked and he will fight back with the only weapon he has, venom. About half of the bites of hobo spiders on humans will be “dry” bites which are harmless.

The Effects of a Hobo Spider Bite

The venom of hobo spiders will have local effects, a large area of redness around the site of the bite. This usually disappears a few hours after the bite, much like a mosquito bite. However, within 24 to 48 hours from the bite, there may develop some blistering at the bite site. In another 24 hours such a blister may burst to give an open ulceration. Within a few days a scab will appear over the lesion. After about three weeks the scab will slough off and the lesion generally heals, leaving a scar. When the bite is delivered to fatty tissue, the local lesion may be deep and extensive and may not completely heal for two or three years.

People bitten by a hobo spider often have reason for concern. In the past few years hobo spider bites have become the number one spider-inflicted medical problem in America. This, even though their range is only in the Northwest part of the country. For this reason, care should be taken by people working in such places as a dark basement or the crawl space under a dwelling. Be especially cautious during the late Summer.

Protecting Yourself Against Bites

Good practice includes full body coverage whenever entering the hobo spider might consider their own domain. Tuck the pants into the stockings. Wear gloves with long sleeves tucked into the gloves. Leave few, if any, crevices where a spider can invade the area between the body and the clothing. A trapped hobo spider might inflict numerous bites as it tries desperately to escape from a threatening entrapment.

The Hobo Spider Life Cycle

The Hobo spider life cycle may be one year; it may be two; this is subject to argument among the experts.

When a Hobo spider reaches its full adult size in June the males and females spend the Summer preparing for egg laying and fertilization in the Fall. The eggs from a female will be deposited in one to four egg cases in late September or October. These egg cases are layers of silk intermingled with layers of soil and debris. They are usually attached to the undersides of rocks or other items found in yards or gardens. Each case may contain 100 or more eggs. Usually, they are not in human living quarters, although they may be in the crawl space under a house. By the time the eggs are secured, there are very few males around, indicating that they die soon after fertilizing the eggs. Who knows, they may be eaten by the females, like the black widow spiders, but this has never been observed.

The eggs hatch early the following June. Since colonies studied in the summer include full grown adults mixed with juveniles, it has been assumed that there is a two year life cycle. During the last half of a summer season many of the mature males will be exploring everywhere they can to mate. This is when most of the encounters with humans take place. At such times there may be large numbers of male hobo spiders entering houses, crawl spaces and basements. There they are seen and come close to people, who are surprised by such large spiders in large numbers.

The male hobo spider will present two protuberances that vaguely resemble boxing gloves. These are not fangs or poison sacs, they are the male genitalia. The female will not have these protuberances, they will have large abdomens where the eggs are being developed. The females seldom wander into human houses.

Black Widow Bites: Symptoms And Treatment

The males black widow spiders do not bite. But female black widows do when their webs are disturbed by people. This usually happens when people are moving items or debris and unknowingly disturb the spider. Areas like sheds, utility boxes and other often undisturbed areas are prime habit for these spiders, so people need to be alert when reaching into these types of areas.

Black Widow Bite Symptoms

Any person who is bitten by a black widow will only feel a pin prick at first. The pain sets in a few minutes later. The pain spreads with varying speeds to arms, legs, chest, abdomen and back, depending on how much venom was injected and the persons natural reaction to the venom. As time goes by the human bitten by a black widow might experience chills, vomiting, violent abdominal cramps, perspiration, delirium, and/or partial paralysis. Any or all of these symptoms may appear within a few hours after the bite.

Black Widow Bite Treatment

Mild symptoms at first may lead to unwarranted complacency, so the bite victim needs to be careful of that. For severe bites professional medical attention should be sought. In mild cases a hot or cold compress can help ease the swelling, and over the counter pain relievers can help with the pain.

Black Widow Venom Effects

Black widow venom is 15 times more poisonous than that of a prairie rattle snake. Of course, a spider will inject much less venom than a snake.  Most black widow spider bites are non-fatal.

Black widow venom contains a number of neurotoxin proteins that have effects on insects. Only alpha-latrotoxin is specific for vertebrates. This compound binds to high-affinity receptors in nerve terminals and causes massive stimulation of neurotransmitter releases. Hence, this material will cause multiple responses in organs and muscles throughout the body. It takes some time for the alpha-latrotoxin in the venom to circulate in the blood steam and make its way to those specific nerve receptors. That is why the effects of a black widow bite may seem trivial at first and then keep on increasing in severity.

The Brown Recluse Spider Bite and Effects

The brown recluse spider doesn’t go around looking for people to bite.  They aren’t aggressive spiders and try to avoid human contact.  Most bites occur when the spider is caught between clothing and the skin of a human or other situations where the spider feels threatened.

How Frequent are Brown Recluse Bites?

There are an average of 2,500 cases of brown recluse spider bites reported to the U.S. Poison Control centers each year.  Most cases are mild to moderate, with only around 30 being severe cases.

There are usually no deaths for brown recluse bites.  However, brown recluse spider bites can be quite serious and you should seek immediate medical attention.

Brown Recluse Spider Bite

When you receive a bite from a brown recluse, there is usually no initial pain.  It can take up to 8 hours till the bite starts hurting.  One of the first signs of a brown recluse spider bite will be an expanding area of irritation.

This will be followed by a skin-killing, necrotic action that occurs a few hours after the bite and continues for days after.

The toxins from the bite spread out from the site of the bite and kill the skin and underlying tissue to form a substantial lesion. The specific toxin involved destroys the membranes that surround the cell of skin and tissue. This skin killing action of proteins in the toxin of brown recluse spider can be especially painful for small children or the elderly.

Brown Recluse Spider Bite Symptoms

Other symptoms might include nausea, vomiting, fever, rashes, muscle and joint pain. While such symptoms are rare among healthy adults, they can be quite pronounced in people with some sorts of weakened conditions.

Brown Recluse Spider Bite Treatment

There is not a set of established treatments for the lesions caused by a brown recluse bite. Many have been tried with varied success.

Ice packs and pain killers often give some of the relief required.

How to Reduce Your Chances of Being Bitten

The Brown Recluse Spider

The brown recluse spider (scientific name: loxosceles reclusa, also commonly called the brown fiddleback spider) can look formidable, especially one that has full grown to having a body ¾ inch long. The it’s long legs make it look imposing. But they get the name ‘recluse’ due to their natural tendency to avoid contact, especially with people.  The brown recluse is a non-aggressive spider, that only bites out of defense.

Identifying the Brown Recluse

Unlike most spiders which have eight eyes, the brown recluse spider has only six, two in front, two on the sides and two in the back. Since it lives in dark secluded places and prowls around at night, it doesn’t need to see very much. Its other senses suffice.

As you might expect, the brown recluse is brown. Some say it resembles a violin, Maybe you will join me in thinking that likeness takes a little imagination. You might live a long time near some brown recluse spiders without seeing one, but because of the size of a fully mature brown recluse, when you see one you will be impressed.

(click on an image to enlarge)

A Brown Recluse Brown Recluse Spider A Brown Recluse Spider (closeup)

Brown Recluse Spider Habitat

Brown Recluse Habitat in the U.S.The brown recluse likes some human habitations and they can be found in wood piles, sheds, cellars, garages, dark closets, under beds, and other places where it is dry and not often disturbed. They like cardboard, some humans say, because it resembles tree bark. They might be found in shoes that haven’t been worn recently, behind baseboards, behind pictures, near to furnaces.

As their name suggests, the brown recluse spiders are reclusive and they prefer to stay out of the way and out of sight. The brown recluse builds a web, mostly as a hiding place, not as an insect trap. This web will be in some dark corner and it will not be very fancy.

Almost all the American brown recluse spiders are to be found in the southern part of the middle of the United States. Not many are ever found along the Atlantic or Pacific Coasts. Not many are ever seen in the Rocky Mountains or the Northern Appalachians.

Brown Recluse Spider Food

At night this spider goes roaming around for food. Unlike most other spiders, the brown recluse spider is not picky about eating insects that have died somewhere along their way. They don’t have to be the killer of their food.

In addition to looking for food, the male brown recluse spider will go looking for females to mate with at night. The female will lay 40 to 50 eggs inside a coat of gray silk about 2/3 inch long. Each female brown recluse spider may produce several coats with eggs in a month. As you can see, given enough other dead bugs to eat and plenty of dark nooks and crannies, a rambling house with few human inhabitants can gain a substantial spider population.

Black Widow Spider Pictures

The while it isn’t aggressive, the black widow spider still makes people uneasy.  It’s powerful venom is enough to give most people pause.

The following are pictures of the black widow spider.  They show the distinct black body shape and the red hourglass shape on the bottom of the spider.  These black widow spider pictures include male and female spiders and should help you identify them correctly.

Click on any of the pictures below to get a larger view.

Pictures of the Female Black Widow Spider

The female black widow spiders cary the distinctly black body with the red markings underneath.  Note: coloration and markings vary slightly by region.  The black widow images below are for the North American spider.

female-black-widow-top female-black-widow-bottom black-widow-bottom-hourglass black-widow-spider

Pictures of the Male Black Widow Spider

As the images below show, the male black widow spider tends to be lighter colored and smaller then the female.

Male Black Widow Male Black Widow (underside) Light Colored Male Black Widow

The Fearsome Black Widow Spider

Few spiders have a well deserved notoriety to match the black widow. Everyone knows that the female will get her eggs fertilized and then eat the male, thus becoming a widow. While this may happen to most such spider couples, it is not necessarily the universal rule. Ever so many stories and movies have been inspired by this model of behavior.

The black widow’s shiny black body is very distinct, which makes them very easy to identify.  A mature female may be an inch and a half in length, including moderate length legs. Both males and females have shiny black bodies with a relatively big black abdomen. Only that female spiders abdomen will have the distinctive red hourglass-shaped spot. If you ever see a male, you will notice it is smaller and it might be lighter in color and have a red or pale brown stripe in the abdomen.

Black Widow Spider
Black Widow Spider

Black widows are definitely web spiders. The silk glands located at the back of the abdomen provide for prolific web building. Oil on the legs of the black widows make it possible for them to hike around on the web without getting entangled themselves.   They build webs to capture insects that might be flying or crawling by. Their poison will kill the captured meal. The typical procedure of excreting digestive fluids to dissolve the prey bit-by-bit and then taking in the partially digested food follows the capture.

A young adult black widow will go through a winter in out buildings, cellars, or other sheltered places. It will have been hatched from an egg ball of 100 to 400 eggs. It might have eaten several brothers or sisters in order stay alive. Remember the doctrine of survival of the fittest. It is a strong belief among black widow spiders. Females can live for five years and produce eggs each year after the first.

In the late spring of each season the surviving spiders will pair off and conduct a protracted courtship activity prior to mating. A mature male will spin a sperm web and deposit sperm in it. He then will load some of the sperm on his antennae and deposit them into the female. When mating is completed the female eats the male and starts laying eggs.

The female deposits her fertilized eggs into a globular silken container in which they remain camouflaged and guarded. She might construct 5 to 15 of the egg balls during a season. All the time she has to be tending her web and capturing prey to support the massive egg production that has to take place in the summer.

It may take 20 to 30 days before the eggs hatch. Maturation may take four to six months. The newly hatched spiders each strive to grow enough to survive the coming winter. As they do this they might eat or be eaten by a close relative or by some other spider.

Black Widow Habitat

Black widows can be found in most of the Western Hemisphere. Three groups of black widows in the United States, northern, southern, and western have some minor distinctions. The southern, by far the most numerous, thrives in the warmer climates and is most often encountered.

Black Widow Spider Bite and Venom

Our other article has more information about black widow spider bites and treatment.