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Spider Pest Control, Spider Extermination, Spider Exterminators, How to Get Rid of Spiders |
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You are here : » » Spiders
Spiders
Structure
Spiders have eight jointed legs and their bodies are divided into two sections; cephalothorax and abdomen. The cephalothorax is a fused head and thorax region. Palps are located in the front and are often mistaken for an extra pair of legs (pedipalps). Their function is sensory, and in the male they are also associated with reproduction. Legs and body may be heavily or sparsely covered with hairs. Although the general appearance of spiders varies, the basic structure remains the same.
Senses
Most spiders have three or four pairs of eyes, situated on the sides and top of the cephalothorax, although some only have one or two pairs.
The bodies of spiders are covered with setae or spines, which appear to be associated with their sense of touch and taste. Acoustic setae, thought to aid in hearing, are located on the legs.
Identification of the sexes
In determining the sex of spiders, the difference in size between adult males and females is usually so marked that it is a useful feature on its own. The male spider is usually smaller than the female of the same species, and its legs are longer than the females. The palps, placed anteriorly, are larger in the male and are a satisfactory means for separating the sexes of most spiders. In some spiders the male palps are clearly swollen and are so characteristic that it is difficult to confuse the two sexes. The abdomen of the female is swollen for reproduction. Sometimes the young may be seen adhering to the body of the female, or she may be guarding an egg sac. Males do not usually spin webs, except in some cases during mating activities.
Life Cycle
After fertilization, the mature female spider produces an egg sac, which varies in size and shape depending on the species. The egg sac of all spiders consists of a mass of silken threads enclosing many eggs. Some spiders leave their sacs near their habitats or in burrows.
The eggs hatch inside the egg sac, and the young moult (shed their skins) once before emerging. On emergence the spiders are known as spiderlings, and in most cases they must obtain their own food. The spiderlings may disperse by ballooning on silken threads. They produce a thread which is allowed to drift in the wind, and as the thread lengthens, the spiderling becomes airborne and is carried some distance. This dispersal avoids competition by overpopulation in a small area.
By successive moults they reach the adult stage, but immediately after a moult the freshly emerged spider is paler and softer than the stage before. Later the body hardens and darkens in colour. Sometimes limbs are lost in encounters with other spiders, or at the time of moulting, but a limb will be entirely or partially replaced, depending on what age it is lost. The younger the spider is when the limb is lost, the more complete will be the replacement. If a limb is lost just prior to the adult stage, the replacement will not be identical with the other of the pair.
The life cycle of most web spinning spiders is less than 12 months, but some ground dwelling spiders develop more slowly and appear to have a life cycle of many years.
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Habits
Most spiders are nocturnal. During the day they are seldom seen, unless they are sought or disturbed in their natural environments. When the light fades, spiders become active. They leave the protection of their burrows or shelters and go out in search of food or, in the case of web spinning spiders, construct their webs to snare prey. As day breaks, most spiders seek the safety of their shelters again.
Reproduction
Courtship in spiders varies greatly, but usually there is considerable preparation, mostly by the male. This involves movements of the palps or a general stroking of the female when the male is at close range. The male of most web spinning spiders drums on the threads of the web and gradually closes in on the female. The activity of the male during courtship appears to suppress the female’s desire for food, since she becomes inactive and in an apparent state of hypnosis.
The mating of spiders is rather interesting in its departure from the generally accepted concept of this act. The male reproductive organ is located in the pedi palpi. The male secretes his seminal fluid on either the ground, some bark or a web specially made for this purpose. He then picks up the fluid on his palps and conveys this to the spermatheca of the female. After the female has been fertilized, the male is often caught and consumed by the female.
Food and Feeding
Cannibalism is well established among spiders. From a very early age, and more frequently when food is short, spiders kill and eat one another. If two spiders are placed in a container, one will eventually kill the other. If a male is confined with a female of the same species, the female invariably kills the male, which puts up little resistance.
Spiders are carnivorous, feeding on living or freshly killed animals (eg insects). Ground dwelling spiders have been recorded as killing small lizards and other creatures, which then have their body fluids squeezed out of them. Some spiders are able to survive many months without food, particularly during winter when food is scarce. Large ground dwelling spiders have been kept in sealed jars with moist sand for three months without food during winter. In warmer months they don’t survive for such periods.
Spiders render their prey immobile by injecting it with venom by means of their fangs. The body of the prey is then squeezed by means of the spider’s fangs and the strong basal section, known as the chelicerae. He mouth is a minute opening located in the region at the base of the palps; it connects with a tubular sucking organ, through which passes the body fluids of the prey being consumed.
Spider Venom
Spider venom is not necessarily poisonous to warm blooded animals. In Melbourne, some spiders are capable of causing death by introducing an extremely toxic substance into the bloodstream of warm blooded animals, including humans (eg. Redbacks), but most spider bites result in no more than localized swelling or irritation. Rarely a spider that inflicts a deep wound may introduce bacteria into the bloodstream, causing septicaemia.
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Production of silk or webs
Silk, or web, is a complex albuminoid protein. Its chemical composition varies, depending on its function. Silk is produced from a set of structures, usually 4-6 in number, called spinnerets.
These are located on the end of the abdomen and connect with silk glands inside the abdomen. Each spinneret consists of many fine ducts, sometimes exceeding 100. Each duct produces an extremely fine thread, and these duct threads are drawn together to form a single thread. The production of different types of silks for different purposes, appears to be related to particular spinnerets. Silk is used for spinning webs; trapping prey; transporting spiderlings through the air; constructing egg sacs and attaching them to foliage; lining burrows; and ground snare lines.
Spider control and avoidance of bites
Other than physical removal, the only effective option for spider control is to use a residual insecticidal treatment applied to spider harbourage areas and feeding areas. In most cases, a synthetic pyrethroid product would provide the best results.
Some advice for the prevention of spider bites:
- Wear gloves when gardening and handling soil or rubbish.
- Wear sensible footwear when walking outside, particularly at night.
- Don’t leave toys, clothes, shoes, and other such articles on the ground, particularly overnight.
- Where extensive landscaping, excavations, digging or gardening has occurred nearby, be alert for disturbed ground dwelling spiders, which may enter buildings.
- Be alert for wandering ground dwelling spiders after long periods of very hot weather, and after widespread application of insecticides. Where spiders are not directly contacted by the insecticide, they may be disturbed and wander more than usual.
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