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Black Widow

The black widow is considered one of the most venomous spiders in Idaho as well as all of North America. Known for their distinctive appearance, females are typically about half an inch long, shiny black with a large globular abdomen and a red hourglass on their underside. Only female black widows bite and it is typically when they are disturbed or protecting their eggs. The females also eat the males (which are typically half the size of females) after mating which gives them their name. Being nocturnal creatures, they are most active at night and can be found in dark corners and crevices especially in garages, sheds, or other areas on the near the exterior of a home.

The bite can cause severe effects to humans since it alters the victim’s nervous system. When first bitten, there may be two small holes from the fangs. The center of the bite may be light red with some darker red around that. The first symptoms occur within 20 minutes to an hour after the bite: there tends to be local pain in the area of the bite followed by general muscle cramps and spasms, abdominal pain, chest pain, weakness, tremor, as well as possible stiffness, chills, nausea, dizziness, fever, difficulty breathing, and/or an increase in blood pressure and heart rate.

Jumping Spiders


The jumping spider is a type of spider that gets its common name from its jumping ability, which it uses to catch prey. Jumping spiders belong to the Family Salticidae. There are more than 4,000 known species of jumping spiders in the world, with about 300 species found in the United States and Canada, including the zebra spider, Salticus scenicus.


Although jumping spider bites are uncommon from these spiders in Idaho, they may cause redness, itching, stinging and swelling. If you suspect a jumping spider has bitten you, clean the site with soap and water. Then, apply a cold compress over the spider bite location. Adults can also take aspirin or acetaminophen and antihistamines to relieve minor symptoms. However, if symptoms continue to worsen for more than 24 hours, it’s crucial to seek medical attention. If possible, bring the spider to the doctor for proper identification and treatment.

Mating Ritual

Jumping spiders conduct complex, visual courtship displays using both movements and physical bodily attributes. Unlike females, males possess plumose hairs, colored or iridescent hairs (particularly pronounced in the peacock spiders), front leg fringes, structures on other legs, and other, often bizarre, modifications. These characteristics are used in a courtship “dance” in which the colored or iridescent parts of the body are displayed. In addition to the display of colors, jumping spiders perform complex sliding, vibrational, or zigzag movements to attract females. It has also recently been discovered that many males have auditory signals as well. These amplified sounds presented to the females resemble buzzes or drum rolls. Species vary greatly in visual and vibratory components of courtship. Many species have patches of UV reflectance, which are exhibited in mature males. This visual component is used by some female jumping spiders for mate choice. If receptive to the male, the female will assume a passive, crouching position. In some species, the female may also vibrate her palps or abdomen. The male will then extend his front legs towards the female to touch her. If the female remains receptive, the male will climb on the female’s back and inseminate her with his palps.


Jumping spiders are generally diurnal, active hunters. Their well-developed internal hydraulic system extends their limbs by altering the pressure of their body fluid (hemolymph) within them. This enables the spiders to jump without having large muscular legs like a grasshopper. Most jumping spiders can jump several times the length of their bodies. When a jumping spider is moving from place to place, and especially just before it jumps, it tethers a filament of silk (or ‘dragline’) to whatever it is standing on to protect itself if the jump should fail. Should it fall, for example if the prey shakes it off, it climbs back up the silk tether. Some species, such as Portia, will actually let themselves down to attack prey such as a web spider apparently secure in the middle of its web. Like many other spiders that leave practically continuous silk trails, jumping spiders impregnate the silk line with pheromones that play a role in social and reproductive communication, and possibly in navigation.

Certain species of jumping spiders have been shown by experiment to be capable of learning, recognizing, and remembering colors, and adapting their hunting behavior accordingly.

Wolf Spider

Often mistaken as a tarantula or nursery web spider, wolf spiders are another spider in Idaho that can be dangerous to residents. The best way to distinguish them is by their eyes. These rather robust, dark brown spiders have eight eyes arranged in three rows: four small ones on the bottom row, two large on the middle row and two medium ones on the top of the head. They vary greatly in size depending on the species and sex. Females are generally larger than males. Also, females carry their egg sac and babies on their backs.

When bitten, fang marks and tearing of the skin may be present if the wolf spider is large enough. Often though, only redness, swelling and pain occurs which can last up to 10 days. Swelling of the lymph glands occurs often as well. Sometimes, the skin around the area will become dark in color. The wolf spider is not as dangerous as the black widow or the hobo but can lead to further complications if not properly cared for.

Brown Recluse


Often identified by a dark brown violin shape on its back, the brown recluse spider is predominantly found in the Midwest and Southeast of the United States. This makes for them being a common spider in Idaho. This species is well known for its “secretive” behaviors, as it prefers to take residence in warm, dry and dark environments, such as woodpiles, basements and closets. This arachnid bites, usually unintentionally when it feels trapped, typically when a hand or foot reaches into a shoe or piece of clothing or a box in the attic or basement where a brown recluse has made its home. The brown recluse or fiddleback/violin spider gets its common names from its coloration and reclusive habits, or the dark violin/fiddle-shaped marking on the top of its chest.


The brown recluse has a venomous bite, and anyone bitten should seek immediate emergency medical help, according to the National Institutes of Health.

Like most spiders, the brown recluse typically only bites when disturbed — though it is possible to inadvertently threaten them. The Idaho A&M AgriLife Extension Program reports that this may happen if a spider is caught in bedding or clothing.

According to The Integrated Pest Management Program at UC Berkeley, 90 percent of bites heal without medical attention or scarring. Reactions to a brown recluse bite vary depending on the amount of venom injected and the individual’s sensitivity levels, reports The Ohio State University. Some people may experience a delayed reaction, others an immediate reaction, and others no reaction at all. Many brown recluse bites leave a small red mark that heals quickly, and the vast majority of bites do not leave scars.

For those with higher sensitivity levels, a small white blister appears at the bite site soon after the bite. The tissue may become hard. Lesions are dry, blue-gray or blue-white patches with ragged edges surrounded by redness. This color pattern has yielded the nickname “red, white and blue,” and, in severe reactions, the bite site can develop a “volcano lesion,” according to The Ohio State University. The damaged tissue becomes gangrenous and leaves an open wound that can be as large as a human hand. It can take eight weeks or longer for full recovery, and scars may result.

Mating Ritual

In the world of brown recluse spiders, males are required to impress females before she will mate with him. During mating seasons, male spiders will try to impress females by performing a mating dance or bringing the female a gift of food. If the female is not receptive, the male spider will try to find a new female to mate with.

Female brown recluses mate just once in their lives to produce eggs throughout their lifetime. From May to July, females produce several egg sacs containing approximately 50 eggs each. The eggs hatch a month later and it takes about a year to grow to adulthood.


The brown recluse gets its name from its color and its “shy nature,” Bills said. “Most spiders go out of their way to avoid humans, which makes sense, considering we are thousands of times larger than they are and don’t have a great record of behaving politely toward them.”

Brown recluses often hide in dark, secluded places, like under porches or deep in closets.  The brown recluse thrives in man-made areas, and may be found under trash cans, tires, etc. It is primarily nocturnal and lays its eggs from May to July.

Brown recluse spiders get around by hitchhiking on furniture boxes and other items from infested structures, according to the Illinois Department of Public Health. They are well adapted for establishing themselves by hitchhiking. They are long-lived, can go for many months without eating, and are adapted to the hot, dry conditions found in many structures. What’s more, a female brown recluse needs to mate only once to produce eggs throughout her life, and can produce 150 or more spiderlings in a year. Thus, a single female hitchhiking into a structure is all it takes to establish an infestation. The need to inspect items before moving them in is clear.

Once established within a structure, brown recluses are often difficult to control. Though hundreds of brown recluses may be present in a house, they may not be easily observed because of their reclusive, nocturnal habits.

Read more about how we treat spider infestations.