CHAPTER 3
SPIDERS

Learning Objectives
After completion of the study of Spiders, the trainee should be able to:

Spiders are seldom ignored. Their distinctive appearance, habits, and intricate webs command attention and evoke strong emotions. Given their due, spiders would 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 3,000 kinds of spiders in the U.S.; they are categorized in the order Araneae. Like their arachnid relatives the mites, spiders live in all parts of the world where they quietly make their way, snaring food in their webs or ambushing insect prey in episodes acted out in minute jungles and deserts.
    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.
    While all spiders are poisonous to some extent, 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 saclike, 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.
    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. Newlyhatched spiderlings use this method to leave the hatching area.
    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 species.

BLACK WIDOW Latrodectus mactans

The Black Widow spider, the species Latrodectus mactans, is distributed over the eastern and southern United States. Two very similar species overlap that range and extend into the western and northwestern states.
    Female Black Widows have large, round, shiny black abdomens usually decorated with two touching red triangles on the belly. They hang upside down in the web, and the red hourglass is obvious. Sometimes dull red dots appear on the back, and occasionally the triangles don't touch, but this 1/2 inch or larger, shiny black spider is unmistakably unique and eye catching. Male Black Widows are small, white and streaked with yellow and red; they are not dangerous.
    Black Widow females are not aggressive but will give full attention to anything that disturbs the web. They weave tangled webs of coarse silk in dark, quiet locations. Mature females are so large they can hardly crawl. While pest management technicians are not commonly called on for Black Widow spider control, they may well run into these spiders when inspecting crawl spaces, porches, garages, and sheds for other pests. Black Widow spiders can be found in stacked pots or baskets, firewood piles, rodent burrows, water meters, stacked boards, under bricks and stones. Usually the spiders are outside, but they may be brought inside, or the young may move inside on ground floors. Western Black Widows are likely to be found outside in bird nests, on low plants and in grape arbors. Move cautiously when treating any potential spider harborage.
    Black Widow bites are immediately painful. The pain at the site of the bite increases during the first half hour following a bite. Two small red marks from the fangs will be noticeable on the skin. After the first half hour other symptoms such as headache, dizziness, shortness of breath, abdominal and back pain set in. Death seldom results from Black Widow bites to healthy adults; children and the elderly, however, are vulnerable. Victims should receive hospital treatment as soon as possible.