COCKROACHES
A 2005 US national study on factors that affect asthma in inner-city children shows that cockroach allergens appear to worsen asthma symptoms more than other known triggers. This study, funded by the US National Institute of Environmental Health Sciences (NIEHS) and the US National Institute of Allergy and Infectious Diseases (NIAID), is the first large-scale study to rank asthma triggers according to severity
ANTS
Typical ants that are classified as pests include pavement ants (otherwise known as the sugar ant), Pharaoh ants, carpenter ants, Argentine ants, and the red imported fire ant. Control of species populations are usually done with bait insecticides, which are either in the form of small granules, or as a sticky liquid that is gathered by the ants as food and then brought back to the nest where the poison is inadvertently spread to other members of the brood — a system that can severely reduce the numbers in a colony if used properly. Boric acid and borax are often used as insecticides that are relatively safe for humans. With the recent insurgence of the red imported fire ant, a tactic called broadcast baiting has been employed, by which the substance (usually a granule bait designed specifically for fire ants) is spread across a large area, such as a lawn, in order to control populations. Nests may be destroyed by tracing the ants' trails back to the nest, then pouring boiling water into it to kill the queen. This works in about 60% of the mounds and needs about 14 litres (3 gallons) per mound.
Ants that tend other insects can indirectly cause pest infestations. Many homopteran insects that are considered as horticultural pests are controlled by the use of grease rings on the trunks of the trees. These rings cut off the routes for ants and make the pest species vulnerable to parasites and predators
RODENTS
Because rodents multiply so quickly, just a few can lead to an out-of-control infestation before you know it.
MOSQUITOES
Mosquitoes are a vector agent that carries disease-causing viruses and parasites from person to person without catching the disease themselves. Female mosquitoes suck blood from people and other animals as part of their eating and breeding habits. The female mosquito that bites an infected person and then bites an uninfected person might leave traces of virus or parasite from the infected person's blood. The infected blood is injected through, or on, the "dirty" proboscis into the uninfected person's blood and the disease is thus spread from person to person. When a mosquito bites, she also injects saliva and anti-coagulants into the blood which may also contain disease-causing viruses or other parasites. This cycle can be interrupted by killing the mosquitoes, isolating infected people from all mosquitoes while they are infectious or vaccinating the exposed population. All three techniques have been used, often in combination, to control mosquito transmitted diseases.
SPIDERS
Not only are their webs a nuisance around the house, but spiders can inflict painful, sometimes dangerous bites. |
