Spiders 101

Thursday, October 3, 2013

A guide to identifying common spider species

 

Spiders 101 pinSpiders get a bad rap. These creepy-crawlies often appear in horror movies, haunted houses and, worst of all, inside our homes where they are usually met with shrieking and the bottom of a shoe. It's easy to understand why people tend to be freaked out by the sight of a spider on the wall. The way they move is startling and unpredictable, their webs are sticky and their hunting methods are rather gruesome. There are also many myths floating around about spiders (no, people don't regularly swallow spiders in their sleep!) that make this pest seem much scarier than it actually is. In reality, almost all spider species found in the United States pose no threats to people.

Despite the benevolent nature of most spiders, there are two species in the southern and western United States that can cause serious harm when accidentally disturbed - the black widow and brown recluse. Below is a guide to help you identify some of the most common types of spiders and the potential threat they can pose to our health.

Black Widow Spiders

Black Widow

  • Appearance: Black widows are black and shiny, with a telltale red hourglass shape on their back.
  • Region: This spider species is found throughout United States, but is most common in the southern states where the temperature is warmer.  
  • Habitat: Black widow spiders are often found around woodpiles and can gain entry into a structure on firewood. They are also found under eaves, in boxes, and other areas where they are undisturbed. Black widow spiders spin their webs near ground level.
  • Threat: While male black widow spiders rarely bite, females are known to be aggressive and bite in defense, especially when guarding eggs. Symptoms of a black widow bite include fever, increased blood pressure, sweating and nausea. Fatalities are unlikely, as long as proper medical treatment is sought in a timely manner. Despite their notoriety, there hasn't been a death in the U.S. due to a black widow bite in more than a decade.
  • Unique Facts: Female black widows were previously thought to kill and consume males after mating, hence their name. However, further research has shown this to be a rare occurrence in the natural world.

Brown Recluse Spiders

Brown Recluse

  • Appearance: Brown recluse spiders are light to dark brown, with a characteristic dark brown violin marking on their back.
  • Region: This species is found in the central Midwest U.S. from Ohio to Nebraska and southward through Texas and Georgia.
  • Habitat: Brown recluse spiders often live outdoors in debris and woodpiles. Indoors, they can be found under furniture, inside storage items and in dark recesses such as baseboards and window moldings. Closets, attics and crawlspaces are the most common hiding places of brown recluse spiders.
  • Threat: Like the black widow spider, the brown recluse spider bites in defense. Bites are often painful and can produce an open, ulcerating sore that requires medical treatment. Restlessness, fever and difficulty sleeping are common symptoms of a brown recluse spider bite.
  • Unique Facts: Male brown recluse spiders wander farther from the nest than females and are therefore more likely to crawl into shoes or other attire. Brown recluse spiders get their name from their coloration and reclusive habits.

Common House Spiders

House Spider

  • Appearance: House spiders are often yellowish-brown in color with an elongated abdomen.  
  • Region: House spiders are found worldwide and are common throughout the United States and Canada.
  • Habits: Inside structures, house spiders are most likely to be found in upper corners, under furniture, and inside closets, basements, garages and crawl spaces. Outside, they are often found spinning webs around windows and under eaves, especially near light sources that attract prey.
  • Threat: House spiders are nuisance pests, but post no threat to people.
  • Unique Facts: Common house spiders have a difficult time surviving in modern homes due to low humidity and fewer insects for food. They are more likely to prosper in garages, sheds, barns and warehouses.

Jumping Spiders

Jumping Spider

  • Appearance: Jumping spiders are compact in shape with short legs. They are usually black in color with pale markings.
  • Region: This type of spider is found throughout the United States.
  • Habits: Jumping spiders build web retreats, which can be found both indoors and outdoors. These spiders frequently hunt inside structures around windows and doors because more insects are attracted to these areas and their vision is best in sunlit areas. Outside, jumping spiders are commonly seen running over tree bark, under stones and boards, and on bushes, fences, decks and the outside of buildings.
  • Threat: Jumping spiders may bite in defense, but their bite is not poisonous.
  • Unique Facts: Unlike most spiders, jumping spiders are active during the daytime and seem to like sunshine. They have the keenest vision of all spiders and are able to detect movement up to 18" in distance.

Long-bodied Cellar Spiders

Cellar Spider

  • Appearance: Cellar spiders are pale yellow to light brown in color with long, skinny legs and a small body.
  • Region: There are about 20 species of cellar spiders found throughout the United States and Canada.
  • Habits: Cellar spiders and their webs are usually found in dark and damp places, such as cellars, basements and crawl spaces. They can also be found in the corners of garages, sheds, barns and warehouses, on eaves, windows and ceilings, and inside closets, sink cabinets and bath-traps. Cellar spiders seem to fare better in areas with higher relative humidity.
  • Threat: Cellar spiders do not bite and therefore pose no threat to humans. Urban legend has it that their venom is the most deadly of all spiders, but their weak mouthparts keep them from injecting venom into humans.
  • Unique Facts: Cellar spiders are commonly referred to as "daddy-long-legs" because of their very long, thin legs.

Wolf Spiders

Wolf Spiders

  • Appearance: Wolf spiders are usually dark brown with paler stripes or markings. They have long, spiny legs and some hair on their body.
  • Region: More than 100 species of wolf spiders arefound throughout the United States and Canada.
  • Habits: Inside, wolf spiders tend to stay at or near floor level, especially along walls and under furniture. Wolf spiders may be brought indoors with firewood. Outside they can be found under stones, landscape timbers, firewood, leaves and other debris. They often rest in such sheltered places during the day.
  • Threat: Wolf spiders can bite, but it's extremely rare unless they are provoked.
  • Unique Facts: Unlike most spiders, wolf spiders don't hunt with webs. Instead, they actually chase their prey using their fast running ability.

Dangerous or not, most people would prefer not to have spiders in their homes. The best way to prevent spider infestations is to remove any possible harborage sites. Spiders are more likely to take refuge in dwellings during the colder months and will gravitate toward dark, undisturbed nooks and crannies. Therefore, homeowners should keep garages, attics and basements clean and clutter-free, avoid leaving clothing and shoes on the floor and seal any cracks or crevices around the home.