Spiders

More than 300 different spiders occur in Missouri. Some of the more common groups include orb weavers, crab spiders, jumping spiders and wolf spiders. These groups are distinguished by the size and shape of their bodies, the structure of the legs and other appendages, and the size and relative position of the eyes. Tarantulas are not very abundant in Missouri but are occasionally collected from the southern part of the state. The brown recluse spider and black widow spider are the only two spiders in Missouri that are considered to be serious threats to human health. Most other species are considered nuisance pests when found in and around homes.

Brown Recluse Spider
It often lives around human dwellings and is found in bathrooms, bedrooms and closets as well as under furniture, behind baseboards and door facings or in corners and crevices. It also likes cluttered cellars and garages and is most active at night. People are sometimes bitten while they sleep, when they roll on a spider in bed. Others may be bitten by spiders trapped in the folds of clothing that has hung undisturbed for a long time.

• The brown recluse is a nonaggressive spider that spins white or grayish, nondescript webs. Its body and legs together cover about the same area as a quarter or a half-dollar, and the body is only ¼ to ½ inch long. The coloring of the recluse varies from an orange-yellow to dark brown or almost black.
• The most distinguishing characteristics are the spider's eyes and back markings. It has six eyes in three pairs arranged in a semicircle on the forepart of the head. This eye pattern is uncommon in spiders and will help eliminate many species suspected to be recluse spiders. The eyes also form the base of a violin-shaped marking on the back. The neck of the "violin" is formed by a distinct, short, median groove It is often called the "violin" spider or "fiddleback" spider
• The spider's eggs are deposited in dark, sheltered areas in off-white, round, silken cases approximately 1/3 inch in diameter. After 24 to 36 days, 40 or more spiderlings emerge from the egg case. Their development is slow and is influenced greatly by ecological conditions and nutrition.
• Bite Symptoms – The effects of a brown recluse spider bite may be immediate or delayed, depending upon the amount of venom injected and the victim's sensitivity. The bite usually causes a stinging sensation and then intense pain. Within 24 to 36 hours a systemic reaction may occur, characterized by restlessness, fever, chills, nausea, weakness and joint pain. The bite also produces a small blister surrounded by a large congested and swollen area. The venom usually kills the affected tissue, which gradually sloughs away and exposes underlying tissues. The edges around the wound thicken, while the exposed center fills with dense scar tissue. Healing may take 6 to 8 weeks, leaving scars of various sizes.

Tips for Control –
• If a home has experienced brown recluse spiders, the occupants can reduce the chances of bites by following the recommendations below:
• Clothing can be stored in sealed plastic bags inside drawers or inside plastic storage compartments hanging in closets.
• Shoes should be stored inside plastic shoeboxes.
• Clothes that have been left on the floor, in a clothing basket, or are otherwise exposed should always be shaken well and inspected before being put on.
• Avoid keeping clothing on floors. Beds should be moved out so they do not touch walls or curtains. Bed skirts around the box springs should be removed from beds, and bedspreads that come near or touch the floor should not be used. These items allow spiders easy access to climb onto the bed. Persons living in infested homes should get into the habit of inspecting bedding prior to climbing in.

• Spiderling are orange, brown, and white, gaining more black at each molt. The spiderlings usually stay near the egg sac for a few days after they emerge. Cannibalism is prevalent during this time. Eventually the surviving spiderlings disperse by means of small silk threads. When they are about one-third grown they establish themselves in some protected place and construct loosely woven webs.
• Black Widows make rather coarse, irregular, tangled webs with a funnel-shaped retreat, built in sheltered spots. They usually remain in their webs for the rest of their lives. As they mature they extend their webs and capture progressively larger prey. Males eventually leave their webs to find females for mating. Females sometimes eat the males after mating; this habit gave the widow spiders their name. The females stay close to the egg mass, biting defensively if disturbed.
• is found outdoors in all kinds of protected cavities. Around houses, it lives in privies, garages, cellars, furniture, ventilators, rainspouts, gas and electric meters and in many other undisturbed places. Widow spiders also are seen in cotton fields and even vegetable gardens.

Bite Symptoms
• A black widow bite feels like a pin prick and sometimes is not even felt. Usually, a slight local swelling and two red spots surrounded by local redness indicate the location of the bite. Pain becomes intense in 1 to 3 hours and may continue for up to 48 hours. Symptoms include abdominal pains, rise in blood pressure, nausea, profuse perspiration, leg cramps, tremors, loss of muscle tone and vomiting. The toxin also causes breathing difficulties and sometimes unconsciousness. Mortality estimates from widow spider bites are less than 5 percent.

• There are many species of wolf spiders (Lycosidae) and they are widely distributed and common. They vary in size from medium to large, some species measuring 2 to 3 inches in diameter. Wolf spiders have long, stout legs -- the fourth pair being the longest. The last two pairs of legs have longer hairs than the first two pairs.
• Wolf spiders are found in a variety of habitats, usually near moist areas such as leaf litter, low-growing vegetation, the edges of streams, ponds or rivers, and on sandbars. They are known to dig burrows or tunnel into natural cavities under objects. They actively stalk their prey during the night, preying on ground-dwelling insects and other spiders. Wolf spiders are known for their wandering habits, and it is not unusual to find some that have wandered indoors
• These hunting spiders are fast runners that will chase their prey. Wolf spiders are hairy and often large, up to 1-3/8 inches long, sometimes confused with tarantulas. Their legs are long and spiny. Many are dark brown.
• Wolf spiders may hunt day and night. They usually occur outdoors, but may wander indoors in search of prey. They tend to stay at or near floor level. They typically construct web retreats in sheltered sites.
• Females carry their large, globular egg sac attached to spinnerets under the abdomen. Upon hatching, the spiderlings climb onto their mother’s back and stay there several days or more before dispersing.
• Wolf spiders frequently alarm homeowners because of their large size and rapid movements. Wolf spiders are not aggressive, but may bite if handled.

Jumping spiders (Salticidae) vary from small to medium-sized with stout bodies and short legs. The cephalothorax and abdomen are nearly equal in size. The body is usually very hairy and is often iridescent or brightly colored. They usually live in the tops of low-growing plants. Males often have peculiar bunches of hairs or spots on their legs and head, and they use these features to attract the attention of females during courtship and mating.
• Unlike most spiders, jumping spiders forage for prey during the day. Since they are active during the day, they are often noticed by humans. They do not use silk to make a web for capturing prey. Instead, they stalk their prey by approaching slowly to a short distance before making a sudden leap onto it. They use silk as an anchor, attaching a strand before leaping. This allows them to climb back to their original location if they miss the prey.

• These spiders have a flattened body and hold their legs at right angles to their sides, presenting a crablike appearance. They can walk forward, backward, or sideways.
• Many crab spiders have horns or ornaments on the cephalothorax or abdomen, and some mimic bird droppings. Those that inhabit trees or hunt on the ground are usually colored with shades of gray, brown, or black, while those that frequent flowers are bright red, yellow, orange, white, and/or green.

• In Missouri, tarantulas (Dugesiella hentzi) are found only in the southern part of the state. This large, hairy species is uniformly chocolate brown with no noticeable markings. Tarantulas prefer drier areas, where they inhabit natural cavities or abandoned burrows of other animals. They stalk crickets and other large insects at night. The structure of their mouthparts is unique among spiders and requires them to elevate their heads to insert their fanglike mouthparts into prey.
• Tarantulas are shy and avoid contact with humans. However, when they are threatened and elevate their heads, this posture is mistakenly interpreted as aggressive. Their venom is only slightly toxic to mammals, so the biggest threat is the puncture that would result from their large fangs.
• Tarantulas are sometimes kept as pets and sometimes become quite tame. Although they can be handled, caution is advised since they can quickly become disturbed and pierce the skin with their chelicerae or fangs. Tarantulas require a constant supply of water in a flat dish into which they can lower their mouths. Tarantula food consists of live crickets, mealworms, caterpillars or other insects. They can go for several weeks without food and sometimes refuse to eat before molting. Tarantulas can crawl up glass and escape through small openings, so they must be kept in a container with a good lid.

• Orb weavers (Araneidae) are often brightly colored with rounded abdomens, some with peculiarly angled humps or spines. However, there is considerable variation in size, color and shape in this group. They are often recognized for building beautiful, large, round webs, on which they rest, head downward, waiting for prey. The webs consist of a number of radiating threads crossed by two spirals. The inner spiral begins in the center, winds outward, and is made of smooth threads like the radiating threads. It covers only the central 1/3 of the web. The outer spiral begins at the edges and winds inward. It is made of more elastic, sticky threads, coated with a liquid substance.
• One of the largest and most commonly encountered members of this group is Argiope aurantia, the yellow garden spider. It may cover an area 1.5 to 2.0 inches in diameter when at rest. The cephalothorax is silver and the oval abdomen has a yellow and black pattern. The legs are mostly black, blending to tan at the bases. The web contains a large zigzag band radiating out from the center. This spider feeds primarily on grasshoppers and katydids.

• Description: 1/8 intch to 1/4 inch. Long thin legs. Body reddish brown. Legs dark with prominent paler coxae. It has eyes on a black turret with 1 eye to the right, and 1 to the left
• Food: Small insects and decaying organic matter.
• Life Cycle: Female thrusts ovipositor into soil to deposit eggs. When warm weather arrives, young creep out and grow slowly. Normally they mature in summer, then mate without courtship. 1 generation a year.
• Habitat: Fields on tree trunks and open ground.
• Range: Throughout North America.

• An important first step is to correctly identify the spider, as this determines which management tactics to adopt that take into account specific biology and habits. For example, if the spider is a web builder, control efforts should target its web because that is where this spider spends most of its time. On the other hand, active hunters are spiders that move about widely, and some species are most likely to contact insecticide-treated surfaces at ground level.
• Within each of the following categories, particular tactics may be more or less applicable, depending on the species of spider:

Preventing spider bites
• Shake out clothing and shoes before getting dressed.
• Inspect bedding and towels before use.
• Wear gloves when handling firewood, lumber, and rocks (be sure to inspect the gloves for spiders before putting them on).
• Remove bedskirts. Move the bed away from the wall.
• Don’t store boxes and other items underneath beds.
• Exercise care when handling cardboard boxes (some spiders may inhabit the space under folded cardboard flaps).

Exclusion
• Install tight-fitting screens on windows and doors; also install weather stripping and door sweeps.
• Seal or caulk cracks and crevices where spiders can enter the house.
• Equip vents in soffits, foundations, and roof gables with tight-fitting screens.
• Install yellow or sodium vapor light bulbs outdoors since these attract fewer insects for spiders to feed upon.
• Many web-making spiders set up residence near lights that remain on at night. Locate such lights away from the house or turn them off when not needed.
• Tape the edges of cardboard boxes to prevent spider entry.
• Use plastic bags (sealed) to store loose items in the garage, basement, and attic.

Sanitation
• Remove trash, old boxes, old clothing, wood piles, rock piles, and other unwanted items.
• Eliminate clutter in closets, basements, attics, garages, and outbuildings.
• Store items off the floor and away from walls in basements, crawl spaces, attics, garages, and outbuildings in order to reduce spider harborage sites.
• Eliminate household pests (prey) such as flies, ants, and cockroaches that attract spiders.
• Do not stack wood against the house.
• Remove heavy vegetation and leaf litter around the foundation.
• Wash spider webs off the outside of the house using a high-pressure hose.

Non-chemical control
• Capture the spider and release it outdoors. An effective technique for capturing hunting spiders is to place a cup over the spider and then slide a piece of paper underneath to entrap it.
• Dust and vacuum thoroughly to remove spiders, webs, and egg sacs (dispose of the vacuum bag in a container outdoors).
• Outdoors, use a water hose or broom to regularly destroy any webs that are constructed on or around the house. Spiders often move elsewhere when their webs are regularly destroyed.
• Use a rolled up newspaper or fly swatter to kill individual spiders.
• Use sticky traps or glueboards to entangle spiders.