Spiders

There are about 40,000 different species of spider worldwide. New Zealand is home to about 2500 kinds of spiders, most of them harmless to people. Some species are ground dwelling, while others live above ground in and on plants and buildings. They prefer warm temperatures and moderate humidity and are easily recognisable by their eight legs.

Most spiders are nocturnal and only appear during the day if they have been disturbed in some way. Different species share different characteristics, habitat, and prey techniques.

There are two types of spiders:

  1. Web spinners- Those which depend solely on webbing to snare their prey seldom move very far and mostly hide in a crevice, curled leaves or camouflaged as twigs.
  2. Hunting spiders- they are a lot less dependent on webs and mostly travel for food.

Identification and habitats of most common spiders of New Zealand

Venomous spiders

There are very few spiders in New Zealand that are capable of causing any harm. Most spiders are a nuisance primarily because of their webbing. The most harmful spiders in NZ are the katipo, the redback and the white-tailed spider.

The katipo (Latrodectus katipo) and the redback spider (Latrodectus hasselti) belong to the same genus as the American black widow spider. These two are the only spiders venomous to people in New Zealand. In both species it is the adult females that are capable of biting humans.

Bites from both species are extremely rare and there is a safe and effective antivenom for both redback and katipo bites.

 

1) Katipo (Latrodectus katipo)
Katipō (Latrodectus katipo)
Katipo spider¹

Female Katipo have black rounded bodies with slender legs and a white-bordered red stripe on their back and a red hourglass mark underneath. Adult males and juveniles are black and white and smaller than the females. The Katipo (meaning ‘night-stinger’ in Māori), a shy native spider, is on the decline in New Zealand due to changes in its habitat. It makes its webs on warm sandy beaches and sand dunes under:

  • beach grasses and other vegetation
  • stones and driftwood
  • debris such as empty tin cans or bottles.

Katipo are found in coastal areas in both the North and South Islands as far south as Karitane and Greymouth.

 

2) Redback spider
Redback spider Latrodectus hasseltii
Redback Spider²

Female Redback Spiders (Latrodectus hasselti) have black rounded bodies with slender legs and a white-bordered orange to red jagged stripe on their back and a red hourglass mark underneath. Adult males are slender with a cream abdomen with brown stripes and juveniles have additional white markings on the abdomen. Both the males and the juveniles are smaller than the females. Redback spiders are originally from Australia. They make their thimble-shaped webs on the undersides of ledges, stone overhangs and vegetation. They are more likely than katipo to make their homes around houses to take advantage

of the warm environment. Small redback populations have been reported in Central Otago (around Wanaka) in the South Island.

 

3) White-tail spider

 

White tailed spiders (Lampona murina and Lampona cylindrata)
White-tailed spider³

White-tailed spiders (Lampona murina and Lampona cylindrata) are quite distinct with dark bodies and a white patch at the end of their cylindrical/cigar-shaped abdomen. The juveniles and males have patches on their abdomen as well as white ‘tails’. White-tailed spiders are from Australia. Lampona murina has been in the North Island for over 100 years and Lampona cylindrata has become widespread in the South Island since about 1980. Both species of white-tailed spider live almost entirely on other spiders. They can be found in vegetation in gardens and bush, and around houses, which they like for the warmth. White-tailed spiders do not build webs. Largely nocturnal, they prefer warm and dry climates, making our houses their perfect residences. They enjoy being outdoors too, under tree bark, mulch, leaves, rocks or logs – but one of their favourite spots is our bedrooms. They are more likely than other spiders to be found where we sleep, with experts believing this could be due to the increased heat from our bodies.

 

Non-venomous spiders

Spiders like the grey house spider, daddy long legs and hunting spiders are a nuisance around houses or in the garden but they are harmless to humans. Non-venomous spiders are of two types- Web Spinners and Hunter spiders.

The most commonly found under this category are:

 

Web Spinners

4) Grey house spider (Badumna longinqua)

 

Grey house spider - Badumna longinqua
Grey house spider

The grey house spider Badumna longinqua is probably the most common spider in New Zealand, and lives in most homes and gardens. It arrived from Australia in the 19th century. Badumna has a comb of special hairs on its back legs, to comb out the threads from its spinnerets. It builds a cobweb with a narrow tube and traps prey with a fine ‘wool’ of threads between the structural threads. Tangled prey vibrate the lines, alerting the spider. These spiders do not usually bite but will strike out if they feel threatened or if they have taken up residence in the toe of a shoe you are putting your foot in! House spider bites are not life threatening; however,

sometimes they do require trips to the hospital when swelling, headaches or lesions are present.

 

5) Daddy long legs (Pholcus phalangioides)
Daddy long legs - Pholcus phalangioides
Daddy long legs spider

Daddy long legs are cellar spiders also known as skull spiders due its cephalothorax resembling a human skull. They are accidentally introduced to New Zealand. Their body length is about 10 mm with very long legs. They build line web indoors, often in the corners, near ceilings and snares flying insects. They immobilise their prey by wrapping them in webbing. They can easily catch and eat hairy house spiders, mosquitoes, and other insects. They are harmless to humans. Cellar spiders are usually dull in colour with banding or chevron markings.

 

Hunting spiders

Hunting spiders rely on stealth rather than webs. Three common species are Crab spiders, Jumping spiders and Wolf spiders.

 

6) Crab spider (Diaea ambara)
Ozyptila Praticola Crab spider
Crab spider

Crab spiders (Thomisidae family) are common on garden plants but are well camouflaged. They wait with outstretched arms for insects to land on the plant, then grab them. Crab spiders usually inject venom into the head of their victim and suck out its insides. They leave the body intact.

 

 

7) Jumping spiders (Trite planiceps Simon)
Jumping spider Trite Planiceps
Jumping spider

Jumping spiders (Salticidae family) have eyesight to rival a primate, and a mammal-like cunning. They will stalk a fly on the edge of a table, then walk hidden towards it, checking its position before pouncing.

If the spider has to approach directly, it will crouch down and move very slowly until close enough to pounce – like a cat stalking a bird.

When you look at a jumping spider closely, it will often raise its head and look back.

 

8) Wolf spiders (Anoteropsis spp.)

Wolf spiders are small spiders with a body length of about 7 mm. They are native to New Zealand. They are an active hunter with good eyesight.

Wolf Spider Lycosidae
Wolf spider

It hunts by day and are able to catch insects bigger than itself. They are fast runners. Female carries white egg sac, attached to her spinnerets, for several weeks.

 

Signs of a spider infestation

In general, spiders can be found in dark, secluded areas, both in your home and garden.

  • Look for spider webs – The size and shape of spider webs vary by species. Some are orb-shaped while others are funnel-shaped.
  • Some spider species live in burrows rather than webs, while others are free-ranging and take refuge in crevices.
  • Some species of spiders are attracted to moist environments. Check your basements, walls, sheds and other damp locations.
  • Other species can be found in places such as attics, the junction of a wall and ceiling, closets and storage boxes.
  • Spiders feed on other insects and prey on ants, flies, woodlice and other spiders, so where there is a plentiful supply of other insects, spiders will wait to find their next meal.
  • As the temperature drops in Autumn, spiders become more active, looking for a mate, and come out of their hiding places. Towards the end of Autumn many die off, but some hibernate until the following Spring.

 

Preventative measure of spider control:

Spiders love clutter because it creates an easy foundation for their homes. Keeping your homes clear of clutter will minimize their presence.

  • Spiders generally enter buildings through gaps in the construction like unscreened windows or spaces between doors and floors. Seal cracks and crevices around door frames, cupboards, pipes, tiles etc
  • Try to minimize any gaps around the exterior of your home that could make it easy for spiders to get inside.
  • Be sure that screens are not bent or torn to prevent spiders from climbing through the cracks.
  • Check pots and garden furniture before bringing them indoors and educate children about the danger of White Tail and Redback Spiders in particular.
  • Keep storage items in plastic, airtight containers rather than in cardboard boxes where spiders can easily enter.
  • Spider eggs are laid into a silken sac, on average about 100 eggs in each sac, which may be fixed to a surface, hidden in the web or carried by the female. Removing these egg sacs can help prevent the spider infestation.
  • Controlling running and jumping spiders food sources around the house is the best way to prevent them from entering your home. Spiders eat other insects, so reducing the other insects around your home will reduce their food sources, and spiders will be less interested in hanging around.
  • Most spiders like to hang out near light sources, which helps them capture flying insects that are attracted to light. At night time keeping the doors and windows closed helps prevent their entry.

 

Control measures

Using insecticides designed to kill spiders is an effective control method, and using these pesticides properly can help to prevent mass infestations of spiders that will require professional pest control.

 

Perimeter Spray Treatment

If spiders are coming indoors, hunting for their prey, spray residual insecticide treatment such as Spider & Insect Spray around all entry points and up to 1 meter from ground around the perimeter of your house. Spray anywhere they are webbing, on decks, under eaves, on porches and other areas on the exterior of buildings. This acts as both a barrier and removes other spiders that would attract spiders like white tails to feed on them. Do not remove webbing until at least 7 days after spraying.

 

Indoor Spray Treatment

Cover all food, food utensils, food preparation surfaces, clothes, toys and bedding and remove fish tanks and other pets from the spray area. Spray the infested areas with Hawkeye Spider & Insect Spray: on the spiders themselves, in ceiling corners, around door and window frames,

on the skirting, under and behind furniture, in clothes cupboards and hot water cupboards.

 

Photo attributions

¹ Katipo – jesscostall CC BY
² Redback spider – Toby Hudson / CC BY-SA
³ White-tail spider – Fir0002 / GFDL 1.2
Grey house spider – Thérèse Oliver, MAF / CC BY 3.0 AU
Daddy long legs – Olei / CC BY-SA
Crab spider – André Karwath / CC BY-SA
Jumping spiders – Thomas Howard / CC BY-SA
Wolf spiders – Raphaël Poupon / CC BY-SA

 

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