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Spiders

Spiders control

Since spiders generally feed off other insects it is imperative that food sources be identified and eliminated.  Spider control is best achieved by treating the upper areas (ceiling/wall junctures) of all rooms with a residual insecticide.  The floor/wall junctures of all rooms must also be treated. Badly infested (lots of webbing & egg sacs) areas such as crawl spaces must be lightly treated with a non residual aerosol.  All webbing should be removed within 3 days of treatment.  The exterior perimeter of the structure must also be treated.  Key areas would be around doorframes, windows and shutters.  These areas would be treated with a residual insecticide  It is advisable to remove any suitable habitat (compost piles, leaves, fire wood), for the crawling insects which the spiders feed upon, from the immediate (10′ ) area of the structure. 

 

 

Funnel-web Spiders

Atrax and Hadronyche 
Family Hexathelidae

Funnel-web spiders are found in eastern Australia, including Tasmania, in coastal and highland forest regions – as far west as the Gulf Ranges area of South Australia. Thirty-six species, including three tree dwelling species, have been identified.

 

Habitat and Distribution

Funnel-webs burrow in moist, cool, sheltered habitats – under rocks, in and under rotting logs, crevices, rot and borer holes in rough-barked trees. In gardens, they prefer rockeries and dense shrubberies, and are rarely found in more open situations like lawns. The most characteristic sign of a Funnel-web’s burrow is the irregular silk trip-lines that radiate out from the burrow entrance of most species. These trip-lines alert the spider to possible prey, mates or danger.

 

Rain may flood burrows and the temporary retreats of male Funnel-webs, causing an increase in their activity. Funnel-webs are very vulnerable to drying out, so high humidity is more favourable to activity outside the burrow than dry conditions. Most activity is nocturnal. Gardeners and people digging in soil may encounter Funnel-webs in burrows at any time of the year.

 

The Sydney Funnel-web Spider

The Sydney Funnel-web Spider (Atrax robustus) occurs in New South Wales, from Newcastle to Nowra and west to Lithgow. They especially favour the forested upland areas surrounding the lower, more open country of the central Cumberland Basin. This includes the Hornsby Plateau to the north, the foothills of the Blue Mountains to the west, and the Woronora Plateau to the south. Funnel-web occurrence is low in much of central-western Sydney, and also the sandy coastal parts of the eastern suburbs and the Botany Bay area. They do better in areas of sandy clay, shale or basaltic soils that can retain moisture more effectively.

 

Other species

Queensland: Hadronyche formidabilis
North Coast, New South Wales: Hadronyche formidabilis, H. infensa, H. valida 
Blue Mountains, New South Wales: Blue Mountains Funnel-web H. versuta & Southern Tree Funnel-web H. cerberea
Central Coast, New South Wales: Hadronyche cerberea, Atrax robustus
South Coast, New South Wales: Hadronyche sp ‘illawarra’ group, Atrax robustus
Southern Highlands, New South Wales: Southern Tree Funnel-web H. cerberea 
Kosciusko, New South Wales: Kosciusko Funnel-web Hadronyche sp 
Victoria: H. modesta & H. meridiana 
South Australia: H. adelaidiensis, H. eyrei & H. flindersi 
Tasmania: Tasmanian Funnel-web Spider H. venenata, H. pulvinator

 

Identification

Funnel-webs are large spiders (1.5 – 4.5 cm body length) with glossy dark brown to black carapace. The abdomen is usually dark plum to black and not patterned.

Males often have a ventral spur or swelling midway along the second leg, which is pointed in Atrax and blunt (when present) in Hadronyche. Spinnerets usually obvious, finger-like and at the end of the abdomen. The eyes of Funnel-webs are closely grouped.

Spiders commonly mistaken for Funnel-webs include: Trapdoor Spiders and Mouse Spiders.

 

Habits, Mating and Reproduction

Female funnel-web spiders spend most of their life in their burrows, but do occasionally hunt on the surface at night. Adult males however leave their burrows and wander in search of females, particularly during summer and autumn. This is when most encounters with humans occur, with males accidentally wandering into houses and garages, often via gaps under doors. The males spend their entire short adulthood seeking as many receptive females to mate with as possible.

 

Male funnel-webs approach the females’ hidden burrows, possibly by following the scent of their chemical attractants. During mating, the male must restrain the female from striking him with her fangs using the spurs on his second legs, while he transfers sperm via his palps into her genital opening.

The female then spins a pillow-shaped silk egg sac, into which she lays over 100 eggs. She cleans and turns the egg sac several times during incubation and will defend it vigorously if disturbed. The spiderlings hatch about three weeks later, and stay with the mother for a few months. After two moults, they leave her burrow, dispersing by foot to eventually make their own burrows. Juvenile males will stay in their burrows until their final adult moult, after which they will become wanderers.

Funnel-webs mature in about two to four years, with the females living to ten or more years, and the males dying about six to nine months after maturity.

 

Toxicity

Bites are most prevalent during summer and autumn when males leave the burrows in search of females. Accidental encounters with wandering males usually occur in gardens, houses, garages and sheds – particularly ground-level dwellings on concrete slabs.

Bites are dangerous and can cause serious illness or death. The venom appears to particularly affect primates (ie humans), whereas other mammals – such as cats and dogs – are relatively resistant.

The male Sydney Funnel-web Spider is more dangerous than the female. This is because the toxic venom component that attacks the human and primate nervous system so severely is only present in male spiders. Initial symptoms after a bite include local pain, mouth numbness, vomiting, abdominal pain, sweating and salivation. Antivenom is available and no deaths have occurred since its introduction.

 

First Aid

People are usually bitten on a limb. Immediate action should be taken to apply a pressure immobilisation bandage and immobilise the bitten limb using a splint. Restrict the victim’s movement. Capture the spider for positive identification. Do not wash venom off the skin, as retained venom will assist identification. Seek medical attention urgently. St John Ambulance Emergency First Aid.

 

Control

For advice on how to minimise the risk of Funnel-web Spider bites, including keeping them out of houses, have a look at our Spiders in the House and Garden factsheet.

 

Redback Spider

Latrodectus hasselti

Redback Spiders are found throughout Australia. They are common in disturbed and urban areas. They belong to the Family Theridiidae, which is found worldwide. The notorious Black Widow Spider (Latrodectus sp) of the United States is a close relative of the Redback Spider, and only differs in appearance by the absence of a red dorsal stripe. Other species of Latrodectus occur in the Africa Pacific Islands, New Zealand, Europe and North and South America.

 

Habitat and Biology

Webs consist of a tangled, funnel-like upper retreat area from which vertical, sticky catching threads run to ground attachments. The Redback Spider favours proximity to human habitation, with webs being built in dry, sheltered sites, such as among rocks, in logs, shrubs, junk-piles, sheds, or toilets. Redback Spiders are less common in winter months. Daddy-long-legs Spiders and White-tailed Spiders are known to catch and kill Redback Spiders.

Insects are the usual prey of Redback Spiders, but they are capable of capturing quite large animals, such as male trapdoor spiders, king crickets and small lizards, if they become entangled in the web. Prey-stealing is also common, with large females taking stored food items from others’ webs.

 

Identification

Female Redback Spiders are black (occasionally brownish) with an obvious orange to red longitudinal stripe on the upper abdomen, with the red stripe sometimes being broken, and an "hourglass" shaped red/orange spot on the underside of the abdomen. Juveniles have additional white markings on the abdomen. Females have a body about the size of a large pea (1cm long) and slender legs.

The males are only about 3-4 mm long and its red markings are often less distinct. The body is light brown with white markings on the upper side of the abdomen, and a pale hour-glass marking on the underside.

Spiders commonly mistaken for Redbacks include their close relatives, the Cupboard Spider (Steatoda sp), the Grey House Spider (Achaearanea tepidariorum) and other members of the Family Theridiidae. Many of these spiders have a similar life history and habits to the Redback Spider.

 

Habits, Mating and Reproduction

Male Redback Spiders do not produce a web, but may be found on the fringe of a female’s web, especially during the summer mating season. The male has to make overtures to the female to discover whether she is ready to mate, which can prove fatal if she mistakes him for prey. It has been found that in order to occupy the female’s attention during mating, the male spider offers her his abdomen by standing on his head and ‘somersaulting’ his abdomen towards her mouthparts. The female begins to squirt digestive juices onto the male’s abdomen while the first palp is inserted. If he is not too weak, he will manage to withdraw, and then insert the second palp. She will continue to ‘digest’ his abdomen. Most males do not survive this process, which seems to be unique to Latrodectus hasselti.

Once the female has mated, she can store sperm and use it over a period of up to two years to lay several batches of eggs. She spends much time producing up to ten round egg sacs (1cm diameter), which are white, weathering to brown over time. Each egg sac contains approximately 250 eggs and only one to three weeks need to pass before more eggs can be laid. These sacs are suspended within the web. Sometimes small ichneumonid wasps parasitise them, puncturing each sac with tiny holes. When the tiny pale-green spiderlings hatch, they disperse by ballooning to another suitable nest site.

Females mature on average in about four months. The smaller male matures on average in about 90 days. Females may live for two to three years, whereas males only live for about six or seven months.

 

Toxicity

Redback bites occur frequently, particularly over the summer months. More than 250 cases receive antivenom each year, with several milder envenomations probably going unreported. Only the female bite is dangerous. They can cause serious illness and have caused deaths. However, since Redback Spiders rarely leave their webs, humans are not likely to be bitten unless a body part such as a hand is put directly into the web, and because of their small jaws many bites are ineffective. The venom acts directly on the nerves, resulting in release and subsequent depletion of neurotransmitters.

Common early symptoms are pain (which can become severe), sweating (always including local sweating at bite site), muscular weakness, nausea and vomiting. Antivenom is available. No deaths have occurred since its introduction.

 

First Aid

Apply an ice pack to the bitten area to relieve pain. Do not apply a pressure bandage (venom movement is slow and pressure worsens pain). Collect the spider for positive identification. Seek medical attention.

 

Control

For advice on how to minimise the risk of Redback Spider bites, see Spiders in the House and Garden factsheet.

 

White-tailed Spider

Lampona cylindrata 
Lampona murina

Family Lamponidae (Araneomorphae)

Both species were described by L. Koch in 1866 and 1873 respectively. 
The genus name is from the Latin lampo = shine; the species names come from the Latin cylindratus = in the form of a cylinder, and murinus = mouse-gray.

 

Features

White-tailed Spiders have a dark reddish to grey, cigar-shaped body (males about 12 mm, females up to 18 mm long) and dark orange-brown banded legs. The grey dorsal abdomen bears two pairs of faint white spots (less distinct in adults) with a white spot at the tip; the male has a hard, narrow plate or scute on the front of the abdomen. The two common species in southern Australia, Lampona cylindrata and L. murina, are similar in appearance and have overlapping distributions in the south-east. Their bites have been controversially implicated in causing severe skin ulceration in humans.

 

Distribution

Lampona cylindrata is found across southern Australia (south east Queensland, New South Wales, Victoria, South Australia, Tasmania, Western Australia). Lampona murina is present in eastern Australia from north-east Queensland to Victoria (Queensland, New South Wales, Victoria,).

 

Biology

White-tailed Spiders are vagrant hunters that live beneath bark and rocks, in leaf litter, logs and detritus in bush, gardens and houses. Tufts of specialised scopulate hairs on the ends of their legs allow them to walk easily on smooth or sloping surfaces. They make temporary silk retreats and spin disc-shaped egg sacs, each containing up to 90 eggs. They are most active at night when they wander about hunting for other spiders, their preferred food. They have been recorded eating curtain-web spiders (Dipluridae), daddy-long-legs spiders (Pholcidae), Redback Spiders (Theridiidae) and black house spiders (Desidae) During summer and autumn White-tailed Spiders are often seen in and around houses where they find both sheltered nooks and crannies and plenty of their favoured black house spider prey.

 

Human interaction/ Threats

White-tailed Spider bites can cause initial burning pain followed by swelling and itchiness at the bitten area. Occasionally, weals, blistering or local ulceration have been reported – conditions known medically as necrotising arachnidism. As well as the spider’s venom, minor bacterial infection of the wound may be a contributory factor in such cases.

A debate continues about the involvement of White-tailed Spider bite in cases of severe ulcerative skin lesions seen in patients diagnosed as probable spider bite victims. Typically, in such cases no direct evidence of spider bite is available. Sensational media reporting of supposed cases of severe "necrotising arachnidism" has given the White-tailed Spider a bad reputation. However, a recent study has monitored the medical outcomes of over 100 verified White-tailed Spider bites and found not a single case of ulceration (confirming the results of an earlier study). The available evidence suggests that skin ulceration is not a common outcome of White-tailed Spider bite.

White-tailed Spiders around your house can be controlled by catching and removing any that you see and by clearing away the webs of the house spiders upon which they feed. 

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