Uniquely among chelicerates, the final sections of spiders' chelicerae are fangs, and the great majority of spiders can use them to inject venom into prey from venom glands in the roots of the chelicerae. The families Uloboridae and Holarchaeidae, and some Liphistiidae spiders, have lost their venom glands, and kill their prey with silk instead. Like most arachnids, including scorpions, spiders have a narrow gut that can only cope with liquid food and two sets of filters to keep solids out. They use one of two different systems of external digestion. Some pump digestive enzymes from the midgut into the prey and then suck the liquified tissues of the prey into the gut, eventually leaving behind the empty husk of the prey. Others grind the prey to pulp using the chelicerae and the bases of the pedipalps, while flooding it with enzymes; in these species, the chelicerae and the bases of the pedipalps form a preoral cavity that holds the food they are processing.
The stomach in the cephalothorax acts as a pump that sends the food deeper into the digestive system. The midgut bears many digestive ceca, compartments with no other exit, that extract nutrients from the food; most are in the abdomen, which is dominated by the digestive system, but a few are found in the cephalothorax.
Most spiders convert nitrogenous waste products into uric acid, which can be excreted as a dry material. Malphigian tubules ("little tubes") extract these wastes from the blood in the hemocoel and dump them into the cloacal chamber, from which they are expelled through the anus. Production of uric acid and its removal via Malphigian tubules are a water-conserving feature that has evolved independently in several arthropod lineages that can live far away from water, for example the tubules of insects and arachnids develop from completely different parts of the embryo. However, a few primitive spiders, the suborder Mesothelae and infraorder Mygalomorphae, retain the ancestral arthropod nephridia ("little kidneys"), which use large amounts of water to excrete nitrogenous waste products as ammonia.
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Birds are a significant hazard to aircraft, but it is difficult to keep them away from airfields. Several methods have been explored. Stunning birds by feeding them a bait containing stupefying substances has been tried, and it may be possible to reduce their numbers on airfields by reducing the number of earthworms and other invertebrates by soil treatment. Leaving the grass long on airfields rather than mowing it is also a deterrent to birds. Sonic nets are being trialled; these produce sounds that birds find distracting and seem effective at keeping birds away from affected areas.
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Mosquitoes are midge-like flies in the family Culicidae. Females of most species feed on blood and some act as vectors for malaria and other diseases. Historically they have been controlled by use of DDT and other chemical means, but since the adverse environmental effects of these insecticides have been realized, other means of control have been attempted. The insects rely on water in which to breed and the first line of control is to reduce possible breeding locations by draining marshes and reducing accumulations of standing water. Other approaches include biological control of larvae by the use of fish or other predators, genetic control, the introduction of pathogens, growth-regulating hormones, the release of pheromones and mosquito trapping.
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Termites with colonies in close proximity to houses can extend their galleries underground and make mud tubes to enter homes. The insects keep out of sight and chew their way through structural and decorative timbers, leaving the surface layers intact, as well as through cardboard, plastic and insulation materials. Their presence may become apparent when winged insects appear and swarm in the home in spring. Regular inspection of structures by a trained professional may help detect termite activity before the damage becomes substantial. Inspection and monitoring of termites is important because termite alates (winged reproductives) may not always swarm inside a structure. Control and extermination is a professional job involving trying to exclude the insects from the building and trying to kill those already present. Soil-applied liquid termiticides provide a chemical barrier that prevents termites from entering buildings, and lethal baits can be used; these are eaten by foraging insects, and carried back to the nest and shared with other members of the colony, which goes into slow decline.
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Various beetles in the Bostrichoidea superfamily attack the dry, seasoned wood used as structural timber in houses and to make furniture. In most cases, it is the larvae that do the damage; these are invisible from the outside of the timber but are chewing away at the wood in the interior of the item. Examples of these are the powderpost beetles, which attack the sapwood of hardwoods, and the furniture beetles, which attacks softwoods, including plywood. The damage has already been done by the time the adult beetles bore their way out, leaving neat round holes behind them. The first that a householder knows about the beetle damage is often when a chair leg breaks off or a piece of structural timber caves in. Prevention is through chemical treatment of the timber prior to its use in construction or in furniture manufacture.
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