Common Pests & Pest Control

Flies

Flies belong to the Order Diptera. There are 98 different Australian families & 7786 different species of flies in Australia alone. Mozzies, house flies, bush flies, & blowies all belong to this group.

Mosquitoes

Mozzies are small flies with long narrow wings with scales along the veins & wing margins. The mouth parts are formed into a long tube for sucking & antennae in males are usually feathered.
The larvae are aquatic & known as wrigglers and are often seen coming to the surface to breathe through a syphon. They especially inhabit still water, often in small spaces like tree holes or even tin cans. The pupae are also aquatic & active. The adult females of most species feed on blood but the males never do. The 275 Australian species feed at different times of the day & a feeding female can swell to twice her size. Many mosquitoes are important disease carriers, acting as transmitters for malaria, dengue fever, filariasis, & other parasites & viruses.

House Flies

Adults are usually stocky & strongly bristled. There are 180 species in this family & two of the most familiar are the Musca domestica, the cosmopolitan house fly & Musca vetustissima, the bush fly. Both are a great nuisance.

Life cycle

Within a week of reaching adulthood, a female adult fly lays batches of about 100 eggs in material suitable for larval feeding. Warm, moist, organic materials are preferred. The tapered, maggot-shaped larvae may hatch within a day. Larvae molt about 4 times during feeding, which may last up to a week or even less in more favorable conditions. Once fed, the larvae usually crawl away from the moist food to find a drier location in which to pupate. The pupae remain immobile for up to a week, at which time the adult emerges. The life cycle of the house fly is usually 2 – 4 weeks but in summer when conditions are favorable up to 12 generations may be produced. Over winter flies will become inactive, hidden & protected, or as larvae that develop very slowly.

The house fly is probably the most annoying insect pest indoors and is found in most parts of Australia. Typically the house fly alternates between materials that are likely to harbor disease causing organisms (e.g. animal excrement) and human foods, utensils & food preparation surfaces. They are known to transmit important diseases such as typhoid & the abundance of house flies in an area is sometimes used to indicate the efficiency of waste disposal & general sanitary standards of that region.

The bush fly is possibly the most widely known & annoying flying pest in the outdoors during Australian summers & is attributable to much of the use of personal insect repellant products during this time. The appearance of this fly is similar to the house fly, except it is smaller & the lifecycle is also similar & usually takes about 2 – 5 weeks to complete. The adults seek large animals, including humans, & remain on & around them for hours at a time, being attracted to sweat, tears, saliva & in the case of grazing animals, faeces. They are known to play an active role in the transmission of certain eye infections to humans & livestock & may also serve in the transmission of enteric diseases of humans.

Some species of flies are predators as adults, & some, like the stable fly, Stomoxys calcitrans, are blood sucking. The stable fly is usually found around dairies & other intensive farming facilities & biting & annoyance of livestock can reduce yields. The larvae of all these flies live in many different habitats, with dead and putrefying flesh, fungi, & rotting vegetation being the most important.

Blow Flies

There are 140 species of these small to medium sized flies. Many are metallic green or blue, others are mixtures of brown & black. The larvae of most of these species develop in dead & putrefying flesh or dung, although there are species that are parasitic. Blow flies will usually lay their eggs in dead & putrefying flesh where the larvae will feed not only on the rotten flesh but on the other larvae. Yuck! While many blowflies are beneficial by speeding up decomposition of carcasses, there are some economically important species which attack living animals. The best known is the introduced Lucilia cuprina which causes ‘blowfly-strike’ in sheep when the larvae start feeding on inflamed skin under the wool, & spread into the flesh.

Life cycle

Spiders

Redback

Long shiny legs a small mid section & large bulbous black abdomen which usually has a broad orange, red or scarlet dorsal stripe. The underside of the female also bears a bright red mark in the shape of an hour glass. Completely black forms are also found. Male spiders are a tiny 3-4 mm, compared to the large female 12-15 mm. These spiders show little aggression and, if threatened, curl up & fall to the ground.

Habitat

Redbacks prefer dry habitats ranging from forests to deserts. They make a loose web in rubbish or debris, and males will surround a female in her web. Around house holds Redbacks can be found in letterboxes, under seats, garden furniture, around pot plants, and in sheds. In areas where Funnel-webs & Trapdoors are found, Redbacks will frequently ensnare & devour these wandering male spiders.

Very toxic. Males do not bite as there fangs are too small to penetrate human skin, but the bite from a female is very painful & can be fatal. However there have not been any fatalities since 1956, when an effective antivenin was developed but this spider must always be treated with caution. Most Redback bites occur when the spider is accidentally picked up or trapped against the hand or body when cleaning out rubbish from a workshop or garden.

Symptoms

Stinging sensation at bite although no sign may be evident
Swelling around bite & paleness; pain & tenderness
Pain in lower limbs due to absorption of venom in lymphatic system
Patient shows shock symptoms: pallor, weakness, profuse sweating - sometimes only round bite site, nausea & vomiting
Some cases show paralysis of lower limbs

Treatment

Keep patient as still & calm as possible
Remove tight clothing & make patient comfortable
Apply cold pack to the bite being careful not to freeze tissue (wrap ice pack in towel)
Seek medical assistance promptly

White Tail

Cigar shaped body that varies from grey to plum to black depending on the age of the spider & when it last molted. Its legs may also be red-brown to black, also depending on its age. The adult has an outstanding patch of white on the dorsal tip of its abdomen. Juvenile spiders have a series of light patches on the top of the abdomen which deepen with each molt until they disappear leaving only the distinctive white 'tail'. Female spiders measure 12 - 20 mm & the slimmer male spiders measure 5 - 12 mm.
These nocturnal open range hunters are not aggressive but like many other spiders will bite if touched or placed on the body inside clothing

Habitat

White-tailed spiders prefer cool places. Outside they can be found under the bark of trees where it builds a temporary tubular retreat sac. Often they can be found in doors particularly in bath rooms where it is cool as well as in bedrooms under clothing left on floors & they have even been found in beds.

Toxicity

Although dangerous, the bite is not lethal. Severe illness & localized pain may be experienced as well as blistering & tissue necrosis. The venom of a white tail contains flesh dissolving enzymes & a microscopic organism Mycobacterium ulcerans, which is what, can cause necrotic (ulcerous) sores.

Symptoms

Clearly visible puncture mark
Burning local pain sometimes followed by blistering & ulceration, however the symptoms have no predictable pattern
The speed of tissue damage & of other symptoms varies widely. Ulceration may begin with surface blistering or a darkening of flesh beneath the bite
Reaction can be rapid & painful, with violent vomiting & diarrhea, or gradual with relatively little pain
If necrosis spreads extensively, the only way to retard damage is to remove the dead tissue & scrape around it. It is thought that the digestive enzyme that causes this damage can renew itself

Treatment

L-Cysteine ointment can counteract the necrotic effect of the venom
Aloe Vera in ointment or fresh leaf form can also greatly help to neutralize the effects of the bite; apply generously over wound 3-4 times a day until it heals
Seek medical assistance as soon as possible hat causes this damage can renew itself

Black House

Robust build with large abdomen, dark brown to black with black legs. The female is a medium sized spider measuring up to 18mm long; the male is only 9mm. There fangs are not obvious but move pincer wise. Their web is a mat with an obvious, roughly round, entrance hole & the spider will wait for an insect to become ensnared. Not an aggressive spider.

Habitat

In the wild they construct their webs in the loose bark of trees, but in & around buildings they make their webs in window frames, in corners, under eaves, in fact any place they have security. These spiders are frequently attacked & devoured by the white-tailed spider.

Toxicity

Toxic. The bite of the Black House spider is poisonous but not lethal. There bites cause some pain & swelling, but the patient soon recovers. Medical advice should always be sought as there may be an allergic reaction.

Huntsman

The Family that Huntsman belongs to, Heteropodidae consists of 13 genera and 94 described species and Huntsman are also known as Triantelopes, Tarantulas or Giant Crab spiders because of their rapid sideways scuttling gait. They generally have a hairy flattened body structure & their front two pair of legs is longer than their back two pair of legs. Some species are quite large, the female being about 40 - 45 mm long & 160 mm across outstretched legs & the male only slightly less. Despite their fearsome appearance these nocturnal hunters are not an aggressive spider.

Habitat

The natural habitat of Huntsman is under the loose bark of trees but they will often enter houses & may be found on walls. If threatened these spiders can & will squeeze into cracks & crevices where no other animal can.

Toxicity

Not toxic. Although a large Huntsman can give a painful bite, most species are entirely harmless to humans.