Steve Tvedten's "The Bug Stops Here"
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Spiders are seldom ignored. Their distinctive appearance, habits, and intricate webs command attention and evoke strong emotions. Given their due, spiders should be prized for their role as predators and natural regulators of insect populations, but because of their appearance and human cultural fears, when one is found to be potentially dangerous, sensationalizing it is irresistible. There are at least 35,000 species worldwide and at least 3,000 spider species and about 40 families in the U. S.; they are all categorized in the class Arachnida, order Araneae. Like their arachnid relatives the mites, spiders live in all parts of the world where they quietly make their way, snaring living prey in their webs or ambushing insect prey in episodes acted out in minute jungles and deserts.

Spiders are a diverse group and are the primary arthropod predators that naturally regulate many insect pests. The two-part spider shape is well known. Its head and thorax are combined to make the cephalothorax. Four legs are attached to each side of the cephalothorax. Spider eyes are in front - some have very large eyes. Like all arachnids, spiders have no antennae or wings and they have 8 legs - insects have 6. They consume up to 2 times their own body weight daily. They live everywhere - some species have been kept alive for over two years without feeding. Population densities of spiders are estimated to range from 27,170 to 5.4 million/ha for some habitats (Bristowe, 1958; Gertsch, 1979).

While all spiders are poisonous to some extent, very few bite humans. Spider mouthparts, located in front below the eyes, have two short needle-tipped appendages, called chelicerae. These needles, or central fangs, are connected internally to poison sacs. The fangs are used to bite prey (mostly other arthropods) and inject poison to immobilize it. Two short leg-like mouthparts help hold their paralyzed prey, while the chelicerae work back and forth tearing the exoskeleton. As blood wells out, it is sucked into the mouth cavity and ingested. Spiders keep working their prey in this way until all the juices are gone and the remainder is a dry crumbled lump. The abdomen is located behind the cephalothorax; it is sac-like, usually globular.

The anal opening is located near the end of the abdomen and close by are some short appendages called the spinnerets. Silk webbing threads out from these spinnerets. Spider silk has great elasticity and can stretch 1/5 of its length without breaking. The silk is protein and is digested by enzyme cleaners that contain protease enzymes. All spiders produce silk, and they use silk in more interesting ways than most other silk producers. Spiders make silk retreats such as tubes and funnels, they make irregular cobwebs as well as the evenly spaced, spiraled great orb webs. Most spiders feed out a dragline wherever they walk and never fall off edges without catching themselves. While spiders don't have wings, they "fly"; nonetheless, by releasing a thread of silk until it is long enough for the wind to catch it and carry them off — the process is known as ballooning. Newly-hatched spiderlings use this method to leave the hatching area. Most species are nocturnal, unobtrusive - often pretending to be dead when molested - most spiders in homes are usually found in undisturbed, dark or dimly lit, cool, damp places - these areas are where people are most likely to be bitten when they "bug", accidentally imprison, or crush these beneficial hunters.

Basically only two spiders are considered dangerous to humans in the United States: the Black Widow and the Brown Recluse. In reality, these two names each represent several different species. Spiders are only distantly related to insects. Unlike insects, they have 4 pairs of legs but lack wings and antennae. Most spiders can be kept out of buildings by tight screens, weather-stripping and caulking. Keep screens and other openings in good repair. Caulk all seams around windows and doors. Indoors: Remove by vacuuming. All spiders are predators feeding primarily on insects and other arthropods but they can survive for very long periods without food. The average spider eats 100 bugs per year. You are never more than 12' from a spider.

Ballooning spiderlings can ascend over 15,000' and have been sighted landing on ships sailing the mid-Pacific. Silk starts as a liquid protein which becomes a solid thread. An orb web may have 1,200 junctions, each crafted perfectly. The spider must calculate the exact length and tension of each succeeding line so the earlier ones don't go slack. Slack lines don't transmit vibrations. The standard orb web is completed in only 20 minutes at about 3 - 4 a.m. Most orb weavers rebuild their webs once a day; they take the web down and eat it to be completely recycled in their body and reused in about 30 minutes. Spiders coat their feet with an oily fluid from their mouths so they don't stick to the webs. Spiders can replace lost legs.

First Aid: For any bite or sting it is important to reduce stress and help the inflicted person to relax. There is evidence that this will reduce the toxic effects of some bites and stings (Ebeling 1975). An ice cube may be applied for a short time to reduce pain at the site of the bite or sting; this does not reduce the effect of the bite, but may make the afflicted person more comfortable. (DO NOT IMMERSE THE WHOLE LIMB IN WATER.) If in doubt about the seriousness of a bite or sting, or if a person is bitten or stung by any of the medically important species discussed in this chapter or book - contact your local poison control center or a physician immediately. Also, collect the spider in question if possible to assist in the treatment of the bite or sting. Always see a physician if bitten by any spider.


The bite of most spider species is not considered to be dangerous. But, any bite or sting may elicit an unusual allergic reaction by persons who are hypersensitive to the bite or sting of a specific species. For this reason all bites must be examined to ensure the safety of those involved. A hyperallergic reaction can lead to anaphylactic shock and in very severe cases, respiratory distress may develop. It is not unusual for a person to have some pain and numbness in the same region as the site of the bite. However, if, for instance, a person is bitten on their hand and their legs begin to swell, this is indicative of a systemic reaction, and this person should receive medical attention as soon as possible.

People who are known to be hypersensitive to other stinging insects such as bees and wasps are not necessarily hypersensitive to spider bites. Likewise, each spider has a very specific type of venom and a person may be sensitive to the venom of one species and not sensitive to the venom of a closely-related species. Lastly, some anti-venoms are available for treatment of some bites and stings, but their availability is variable. Contact your local poison control center for information regarding anti-venoms if dangerous spiders are a problem in your region.

  1. Inspection - A thorough inspection of the building is essential and should be made at night because most spiders are nocturnal.

  2. Proper Identification - Accurate identification is important for both pest management and medical reasons. Place glue boards/monitoring traps or duct tape (placed sticky-side up) in the area where the spider was seen.

  3. Prevention/exclusion - This consists of making sure that the building is in good physical condition, and properly screened and sealed to reduce entry. Also, changing the exterior lighting to off-building locations, from mercury vapor to sodium vapor lamps or amber lights, or in the case of homes, changing the bulbs near the entrances to yellow bulb, may be of some help in reducing insect/spider attractive- ness. Install vapor barriers, vents, fans, air conditioners, and/or dehumidifiers to change the conditions conducive to infestation.

  4. Sanitation - Such practices consist of keeping the premises free of debris such as boxes, papers, clothing, scrap and lumber piles, etc.; it is wise to wear protective gloves and clothing when cleaning out such accumulations of clutter. A thorough housecleaning should be done a minimum of twice each year. Try lightly sprinkling talcum or medicated body powders or Comet® around sill boxes and openings. Routinely vacuum and clean with Safe Solutions, Inc Enzyme Cleaner with Peppermint (1 oz. per gallon of water).

  5. Mechanical measures - The key to control is the timely mechanical removal of all visible spiders, webs, but especially the egg sacs with a vacuum, both inside and outside; seal or wrap the bag in plastic and properly dispose of the bag immediately after you finish vacuuming.

  6. Spray - 1 oz. of Safe Solutions, Inc Enzyme Cleaner with Peppermint per quart of water will kill most spiders in a few seconds.

  7. Dehumidifiers and Ventilation - The reduction of moisture reduces many insect infestations which limits spider food sources. Spiders like most arthropods are also very sensitive to moisture loss and will quickly leave overly dry conditions. So properly ventilate and install and maintain fans and/or air conditioners and/or dehumidifiers in basements, crawl spaces and attics.


When webbing is found, either vacuum or sweep it down, which will also eliminate spiders and egg sacs. This will help you determine your degree of control on future visits. Note: 1 acre may contain 2 million spiders. There are about 50 spiders for every square foot of grass. Remove or exclude the insect pests they feed on. Routinely steam clean or thoroughly wash/clean with Safe Solutions, Inc Enzyme Cleaner with Peppermint and/or borax. Remember spiders are beneficial creatures.

  1. Vacuum up all visible spiders, webs and/or egg sacs (300 hundred spiders may be in one sac).

  2. Routinely clean (with 1 oz. per gallon) or spray (with 1 oz. per quart) of Safe Solutions, Inc Enzyme Cleaner with Peppermint and/or borax. Borax will kill plants.

  3. Spray straight 5% white distilled vinegar with a teaspoon of coconut oil to help remove and help prevent spider webs.

  4. Routinely steam clean or vacuum the entire area. Do not store clothes, packages, materials for extended periods of time without cleaning them all or sealing them in plastic.

  5. Lightly sprinkle talcum or medicated body powder or Comet® or food-grade DE in sill boxes and along walls, etc.

If you still are seeing spiders, &read The Best Control© or The Best Control II© on CD-ROM.


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