Identification and Life Cycle
Spiders are in the class Arachnida, which also contains scorpions, harvestmen, pseudoscorpians and ticks. The more common species of spiders found in New York State are the Cellar spider, Cobweb spider, Funnel Web or Grass spider, Jumping Spider and the Sac spider. Another common species is the “Daddy-long-legs” or Harvestmen, which is often confused with the cellar spider. Daddy-long-legs are not true spiders, but spider relatives.
Spiders have eight legs (4 pairs), an antennae, and most species have eight or six eyes. They all vary in size, shape and color. They do not have chewing mouthparts, but have jaws that include hollow fangs through which venom can be injected to immobolize or kill their prey.
They lay eggs within a silken egg sac that is often ball-shaped and either hidden in the web or carried by the female. They may produce up to 3,000 eggs in a series of several sacs over a period of time. Young spiders emerge from the egg sac and separate, climbing to the top of a nearby object to be carried by the wind. This is called ballooning. For a spider to grow, it must shed its skin, usually 4 to 12 times before it reaches maturity within 1 year.
Habits and Damage
Some spiders stray indoors during warm weather, although they can be found indoors any time of year. Their numbers may increase during late summer and fall when they search for winter hibernation sites. In homes, they feed on household flies and insects. Outdoors they are beneficial to the environment, feeding on insects such as flies, crickets, and mites.
Spiders produce silk, secreted liquid through spinnerets, which hardens on contact with air. Some spiders use web snares to trap prey, and all construct a silk sac to deposit eggs. Many will use these “web” lines to move long distances by simply dispersing more line into a breeze that carries them away.
Indoors, they prefer to live in disregarded areas such as attics, basements, crawl spaces, behind and under bookcases and furniture, wall corners and baseboards. Most spiders are harmless to humans and will not usually attempt to bite unless trapped or held.
- American House spiders or Cobweb spiders typically hang upside down on its web in wall corners, doorways and under furniture.
- Cellar spiders prefer the outdoors, but can be found in dark corners of a basement or cellar. They are often confused for daddy-long-legs, and crane flies.
- Sac spiders are typically a light yellow color and may bite humans if they feel threatened. The venom from its bite can cause some individuals to have localized redness, swelling and itching.
- Funnel Web Grass spiders are brownish or grayish with light and dark stripes near its head. They build webs around steps, window wells and low shrubs.
- Daddy-Long-Legs or Harvestmen are not actually spiders, but are a relative. They hunt small insects and feed on plant juices. They do not have venom.
- Jumping spiders have large eyes, stocky bodies and strong legs. They can jump while catching prey. They may be found on windowsills or in mailboxes.
Prevention and Management
The best strategy for spider control is prevention. An Integrated Pest Management (IPM) program can properly identify the pest and help you maintain a spider-free environment.
It is important to recognize and alter conditions around a home or building to limit areas where spiders can gain access from outside.
Exclusion. Limit areas where spider can gain access into buildings, especially around doors & windows.
Sanitation. Reduce the possibility of an infestation by eliminating sources of food.
Habitat modification. Eliminating or up-keeping preferred spider locations will help keep the populations low.
The following steps can be taken to help prevent or reduce a potential problem with spiders.
- Provide suitable drainage for basements, cellars, and crawl spaces under the building to reduce moisture.
- Dry out damp areas by using a dehumidifier.
- Vacuum the spider’s webs and egg sacks. Dispose of the vacuum bag promptly.
- Fill all visible cracks and voids in the foundation as well as using a sealant or weather-stripping around windows, doors and screens.
- Install door sweepers to insure that doors close tightly.
- Clean-up woodpiles, trash, rocks, compost piles, and other debris where spiders often live.
- Move and dust often behind and under furniture, wall hangings and the corners of ceilings.
- Knock down webs, egg sacs and spiders around the outside of your home with a high-pressure hose.
- Use yellow or sodium vapor light bulbs at outside entrances to reduce flying insects that attracts spiders.