Spiders
Some spiders like moisture and are found in basements, crawl spaces, and other damp parts of buildings. Others like dry, warm areas such as subfloor air vents, upper corners of rooms, and attics. Most spiders hide in dark areas. Contrary to popular belief, spiders are not insects; rather, they are arachnids. Being arachnids, they have two body segments, eight legs, and do not have wings.
Only two species are harmful to humans in the United States.
Spider facts:
Most common types of spiders found in the house and yard area:
- Black Widow: They live an average of one year, although some species may survive for up to three years. These spiders live longest in captivity. Black widows are the largest of web-spinning spiders..
- Brown Recluse: Adult specimens vary in color from dull yellow to tawny, dark brown. Younger spiders are lighter in color than adults. The abdomen of the brown recluse has no stripes or spots. Loxosceles Reclusa spiders have six eyes, which are arranged in pairs known as dyads.
- Garden Spider: Garden spiders are not aggressive and are more likely to retreat from than attack humans. However, in cases of extreme provocation, garden spiders may bite. Their bites are harmless to humans.
- House Spiders: are not necessarily lethal to humans. Small, controlled populations can even prove useful, as they consume other unwanted household pests.
- Jumping Spider: The most common jumping spider that is found in homes in North America is the Phidippus Audax, also known as the daring jumping spider and the bold jumper.
- Wolf Spider: Wolf spiders are named as such due to their predatory habits: like the wolf, these spiders are robust, agile hunters. They belong to the family Lycosidae that comes from the Greek word for "wolf".
Common Spiders
Black Widow
Black widows are identified by red hourglass markings on the underside of their abdomens. Black widows are shiny black in color. Females are larger than males and can measure up to 10 millimeters in length. These spiders are members of the genus Latrodectus.
Black widow spiders favor dark, secluded areas such as crevices and woodpiles. They thrive primarily in temperate zones and are known to live in the American South. They may also be found in locations as remote as Canada.
Five species of Latrodectus or "widow" spiders are present in North America. The most common is the southern widow, or Latrodectus Mactans, and is found in the American South and Northeast. The Latrodectus Hesperus is more populous in the west and the Latrodectus Variolus, or northern widow, is found more commonly in the American Northeast. There are two species that are primarily found in Florida. These are the "red widow" or Latrodectus Bishopi and the "brown widow" or Latrodectus Geometricus.
Although black widow spiders are named for the female's propensity to kill the male after mating, this behavior rarely occurs outside of captivity. In laboratories and cages, females and males are kept in extremely close proximity. In natural conditions, males almost always successfully elude females after mating.
Male black widow spiders are considered innocuous, as their venomous organs are not used after they reach maturity. However, females are capable of injecting venom. In extreme cases, the venom of the black widow spider severely weakens the nerves and the brain, leading to impaired breathing, body aches and nausea. Death is more likely in very young or old individuals.
Brown Recluse
Although all spiders are capable of biting, most spider bites cause little harm to humans. However, bites from spiders such as the brown recluse can result in necrosis and severe illness. Long-legged and yellow-tan in color, brown recluse spiders of both genders are best distinguished by a fiddle-shaped pattern close to the eyes. Adults measure approximately ½-inch in length.
Brown recluse spiders dwell in dark, sheltered places and can be found in homes, barns and basements, as well as outdoor habitats. Webs tend to appear disorganized and are built most commonly near ground level. The spider is a hunter, so the web is not intended to catch prey. The brown recluse is located throughout the midwest and south of the U.S.
Brown recluse spiders are shy and rarely bite unless provoked. They are incapable of biting through clothing and bites sometimes go unnoticed until effects become obvious a few hours later. A pale blister ringed in red appears at first. Fever, convulsions, nausea, and weakness set in within one day. If untreated, the early blister may become a lesion, resulting in necrosis and severe nerve damage.
Because brown recluse spiders are solitary and secretive, it can prove difficult to locate their dwellings. Almost any dark, undisturbed area can serve as harborage for brown recluse spiders. In nature, these spiders can be found beneath rocks and logs.
However, human-altered environments provide better conditions to brown recluse spiders than these natural settings. Brown recluse spiders may live inside boxes, clothing, shoes, furniture, bedding, rubber tires, and other dry, dark, warm locations. Storage areas such as closets, basements, and cellars are commonly inhabited. Because of their high reproductive potential, it is more common to find many of these spiders than to find just one.
Geographically, brown recluse spiders have become an endemic to the American South and Midwest. Although brown recluse bites are claimed in states outside of these regions, these bites are most commonly a result of a different species exhibiting similar physical characteristics.
Garden Spiders
Garden spiders are common in Europe and Southeast Asia, as well as in the United States and Canada. As their name suggests, they are found outdoors and in gardens. Garden spiders are not aggressive and are more likely to retreat from than attack humans. However, in cases of extreme provocation, garden spiders may bite. Their bites are harmless to humans.
Garden spiders are known as orb weavers due to their orb-shaped, delicate webs. Even garden spiderlings are capable of spinning these intricate structures without the assistance of mature spiders. The webs of garden spiders are notoriously strong.
The garden spider uses its web to capture food. Although their eyesight is poor, garden spiders are extremely sensitive to vibrations along the strands of their webs. Positioning themselves at the center of their web, garden spiders hang upside down, jump on prey and paralyze it with injected venom. Like other spiders, garden spiders must liquefy their prey in order to consume it.
The garden spider also uses its extraordinary sense of touch for mating, as males tap upon the webs of females to express their intent. Because males spend the mating season obsessively seeking partners, they typically die of exhaustion and malnutrition following fertilization.
The most common spiders found in gardens are grass spiders, orb web weavers, elongated long jawed spiders, cobweb weavers, daddy long legs, sac spiders, and crab spiders. These species are also known to enter human habitats.
Grass spiders typically reside between the leaves of plants. Their webs can be located in hidden corners of gardens.
Orb weavers build unique, incredibly strong webs between branches. They use the webs to capture flying prey and house their egg sacs. These webs may be constructed on a daily basis.
Elongated, long jawed spiders are similar to orb weavers, as they also construct orb-like webs. However, their webs are hollow at the center and are constructed facing the sun.
Cobweb weavers are also commonly found in gardens. These arachnids hang upside down to wait for prey and build their webs in secluded areas. Cobweb weavers construct their homes in areas safe from rain and wind. They are often mistaken for black widows due to similarities in appearance. However, cobweb weavers are not harmful to humans.
House Spiders
Of the many species of identified spider species, house spiders are the most frequently found in human dwelling places. Although their presence is discomforting, house spiders are not necessarily lethal to humans. Small, controlled populations can even prove useful, as they consume other unwanted household pests. Several species are considered house spiders. Some of the more prevalent house spider species include the common house spider, the domestic house spider, the aggressive house spider and the brown house spider.
A house spider's body is divided into the cephalothorax and the abdomen. Like scorpions, mites, and ticks, house spiders are wingless. They are classified as arachnids rather than insects and have eight, single-lens eyes.
House spider webs are typically funnel-shaped and can be located in various places within a home, including windows, ceiling corners and above or beneath fixtures. House spider webs are large and constructed of thin silk threads. They serve both as dwelling places and as traps for prey. House spider's preys are paralyzed by venom injection before being broken down by digestive juices. As a result, preys are liquefied to allow for consumption.
House spiders rarely bite unless they feel threatened. However, spiders are often frightened unknowingly, as when they reside in shoes or clothing being put on by a human.
While the bites of most house spiders are harmless, that of the aggressive house spider - also known as the hobo spider - can be very dangerous. Like the black widow and the brown recluse, the aggressive house spider delivers a painful, venomous bite when provoked. Large, ulcerous wounds result and may be accompanied by mental disturbance, among other symptoms.
In the event of severe swelling, lesions, or headaches, victims should immediately seek medical attention. If possible, take the spider along for proper identification. Although most spiders found within homes are not deadly, it is best to allow a medical professional to determine the severity and danger of a bite at the first sign of pain or incapacitation.
Jumping Spiders
Jumping spiders belong to the Family Salticidae. With over 4,000 species known throughout the globe, tropical regions are most influenced. However, some species thrive in the frigid Himalayas. Over 300 species exist within North America. Jumping spiders tend to exhibit dull coloration, although the bodies of some males may glisten.
Jumping spiders are known for their swift reflexes and leaping abilities. These spiders are capable of leaping as high as 25 times their own size and as such, are extremely capable predators. Jumping spiders also possess impressive eyesight.
Although jumping spiders are not web-weaving arachnids, they do produce silk. Their silk is used to mark retreats and to protect eggs. Silk may also function as a dragline while jumping, allowing jumping spiders to control their fall and trace their steps.
Among arthropods, jumping spiders, or Salticids, are known for their superior eyesight. Jumping spiders are equipped with eight eyes, four of which are apportioned to the face and four of which are located at the highest point of the carapace. Long and tube-like, the two eyes located at the center of the face have limited perspective and high resolution. In contrast, the other eyes have low acuity and a wider field of view.
Jumping spiders are also famous for their agility. Jumping spiders are some of the fastest moving arthropods in existence and, as their name suggests, are capable of leaping. The circulatory system of these spiders is responsible for their mobility. When blood pressure rises in their limbs, their bodies move by way of released pressure.
Wolf Spiders
Wolf spiders are hairy arachnids that can grow up to five inches in leg span. Quick moving and relatively large in size, wolf spiders inspire fear when they are found within human dwellings. Wolf spiders are also sometimes confused for tarantulas. However, occurrences of wolf spider bites are extremely rare and are not known to be deadly.
The Carolina wolf spider is the largest documented wolf spider in the United States. Its color matches its habitat, allowing for camouflage. Other wolf spider species may inhabit alpine meadows, coastal forests, dry shrub lands and woodlands. Most species are burrowers that live underground, although some specimens can be seen traveling above ground in leaf litter, on lawns, and in gardens. Most wolf spiders are also nocturnal, although some do hunt in the morning. A wolf spider's diet typically consists of insects and other small spiders.
Although their reputation would lead one to believe otherwise, the bite of the wolf spider is never fatal. The effects of a wasp or bee sting are considered to be more deadly than those of the wolf spider's bite. Wolf spiders also do not bite unless threatened or provoked. In most cases the wolf spider will first retreat or rear up on its legs, exposing its large fangs.
However, some individuals may experience allergic reactions to wolf spider venom. Symptoms range from mild skin irritation to muscle pain, fever, vomiting, and nausea. Wolf spider bites result in local pain, redness and swelling of lymph glands. The skin surrounding the entry wound may turn black. Wounds should be washed with soap and water. Ice packs should be applied immediately in order to prevent swelling. Bandages and tourniquets are not necessary. Medical attention should be sought in the event of severe effects or allergic reactions resulting from any spider bite.
Wolf spiders are commonly mistaken for other, more venomous spider species. It can prove helpful to capture the offending spider and bring it to the doctor for proper identification at time of treatment. As well, contacting a local pest control agency could be helpful if you discover numerous spiders in your house or around your property.
Other Types of Spiders
Hobo Spiders
Crab Spiders
Ground Spiders
Spinybacked Orb Weaver Spiders
Tarantula
For information on other pests, visit the "Pest Index" home page.
