Spiders - Identify and Control
Although some people are scared of spiders, in New Zealand there are only a few species that should provide a cause for concern; the katipo, the redback, the cupboard (or false katipo) and white-tailed spiders. Of these the katipo is the only spider native to New Zealand. A bite from one of these may well require medical treatment, most people want to keep all spiders out of the home, especially if you have small children and pets around.
There are two types of spider from a control point of view;
web-building spiders (katipo, redback, cupboard spiders)
running or hunting spiders (white-tailed spiders).
Control of web-building spiders is relatively easy but control of running spiders is a lot more difficult. However, with a combination of preventative measures and appropriate treatments, you can certainly make a spider encounter a rare occurrence.
THE THREE INTRODUCED SPIDERS OF NEW ZEALAND WITH NASTY BITES:
REDBACK (KATIPO IS VERY SIMILAR)
CUPBOARD SPIDER OR FALSE KATIPO
WHAT DO SPIDERS LOOK LIKE?
Most people will know a spider has eight legs (and two body segments). As such they are arachnids and not insects – insects have six legs and three body segments. Although identifying spider species can require expert knowledge, most of the common pest spiders are easy to recognise.
Katipo: Female katipo have rounded black bodies, with a white-bordered red stripe on their back and a red hourglass mark underneath. They are easily confused with redbacks. Adult males and juveniles are black and white and smaller than the females. Katipo are found on or near warm, sandy beaches. It is becoming rarer over recent years. There is also a black katipo which is mainly found in the north of the North Island, but is not considered dangerous. The katipo, although dangerous, is not considered a pest and is protected as an endangered species.
Redback spider: Female can be up to 3cm (male is many times smaller). Although we all expect a black spider with a red mark on the abdomen, young Redbacks tend to have a patterned mark rather than a red mark and sometimes adults can be almost completely black. Still confined to limited areas, primarily around Auckland and also in central Otago. More likely to be found building webs around the home than the katipo.
Cupboard spider (or False katipo): This spider which comes from South Africa is now widespread in New Zealand and range from black to dark brown in colour with only very feint red markings to the rear most part of the abdomen.
White-tailed spider: A slender spider up to 2.5 cm long with brown and black striped legs. White tip to the abdomen.
Grey House spider: A grey / black spider up to 2.5 cm, with a feint pattern on the abdomen. Typically builds webs around windows, doors and eaves, often with a funnel like entrance. (But it’s not a Funnel web spider, they build webs in the ground and under logs).
Huntsman: These large, fast moving spiders have been introduced from Australia. Although large in size, that are quite timid (unless guarding an egg case) and their bite is not considered dangerous.
Tunnel web: These are the largest spider in New Zealand by weight and are commonly found in Wellington.
Young spiders are generally miniature forms of the adult and often remaining on the female or near the web until bigger. The young hatch out of egg cases which are white round or disc-like, dense balls of webbing material. If you see an egg case near a spider, it is likely it will be more aggressive, so beware!
SIGNS OF AN INFESTATION
An infestation of web-building spiders is fairly easy to spot; a build up of webs on the house or in the garden, although the more dangerous spiders, such as the redback or cupboard spider, may be harder to spot as their webs are a little less obvious. Their webs tend to be more open and messy (like a fishing net), often with leaves and other debris incorporated. They also like hiding under rocks and inside tubular metal fencing, making their webs difficult to see.
It is very rare to have an “infestation” of running spiders. Certainly, there can be occasions when running spiders are more common. As a general rule, if you have lots of web-building spiders (indicating good conditions and plenty of insects for food), you will also get an increase in running spiders.
MAIN PEST SEASON
Spiders will be more common in the warmer months and often spider numbers will be higher if the spring is warmer and wetter than normal. Spiders building their nests indoors will be active all year round.
Katipo: Lives in coastal areas on warm dunes and surrounding areas. It’s numbers appear to be reducing probably due a combination of destruction of habitat and being out competed by the false katipo. It’s name means “night stinger”.
Redback spider: Redbacks live in dry sheltered sites, under rocks and logs, in tubular fencing, in roof voids… in the outside dunny! The female Redback will often eat the much smaller male spider after mating.
Cupboard spider: They get their name from their like for sheltered, undisturbed places to build their webs (such as cupboards). Their webs may be difficult to spot, but their presence can be detected by their droppings – white spots (like small splashes of paint) on the floor underneath webs.
White-tailed spider: Prefers cool moist locations, such as the mulch in garden beds. Will come inside in Summer to escape the heat, often hiding in sheets and clothing on the floor. Their favourite food is other spiders.
Huntsman spider: Huntsman spiders tend to live under rocks and bark (thus their very flat body shape – which make them very adept at squeezing into cars!).
If you suspect you have been bitten by a katipo or redback, you should seek urgent medical attention.
If you think you have been bitten by a spider, clean the wound with antiseptic or warm soapy water and place ice on the bite (not directly on the skin).
If you can catch (safely) or take a photo of the spider, it can allow the species to be identified to ensure the correct treatment.
Although white-tailed spiders also give a nasty bite there is no evidence that their bites give rise to skin necrosis (a bit of an urban myth!). However, if you get a reaction at the site of a spider bite (no matter the species), seek medical attention as soon as possible.
SPIDER PREVENTION TIPS
Keeping garden beds away from the edge of the house will significantly reduce the spider population.
If garden beds next to the house are kept in place it is important to keeping vegetation trimmed back from the edge of the house and paths.
Keep clothes and shoes off the floor to reduce spider hiding places.
SPIDER CONTROL TIPS
A crawling insect aerosol should be kept on hand to spray the occasional unwanted spider. Ensure the spider receives a good dose and keep your distance. PestXpert Spider Blast Eliminator with its extra power is an ideal option.
The best treatment for web building spiders is to spray their webs and hiding places with an insecticide (ready to use pump back or aerosol). The key tip to get the best performance is to wait a day or two after spraying before brushing down any webs. This ensures the spiders will have picked up a lethal does of insecticide (by walking on the web) and by using a brush (rather than hose), you can ensure the insecticide remains in place to prevent new spiders taking up residence.
To prevent web-building spiders taking up residence in the first place, spraying around doors, windows and vents, as well as under eaves and guttering delivers excellent results. As these spots tend to be sheltered from sun and rain, the treatment can last many months. To get deep into hiding places you can use the power of PestXpert Spider Blast Eliminator.
It is a lot more difficult to prevent running spiders, such as the white-tailed, entering the home. Carrying out a preventative spray around the perimeter of the home and any openings will have some benefit, although running spiders often walk on the tips of their legs, preventing them from picking up a lethal dose of insecticide. However, if you carry out a preventative treatment for web-building spiders and other insects, the chances of running spiders coming in are reduced, as there is little prey around.
NB. The katipo is fully protected under the Wildife Act as a protected species, which means actively killing a katipo can be punishable by fine or imprisonment. However, given their natural habitat is in and around sand dunes, a treatment around the perimeter of a property is highly unlikely to cause an issue.
PESTXPERT SPIDER PRODUCTS
Spider Blast Eliminator is the ideal product for spot treatments of spider hiding places. With its unique high power, 5 nozzle spray, it can get deep into crack and crevices. It’s also great for direct spray of spiders, as you can keep your distance!
For long lasting preventive treatment use Pro-Spray Outdoor Perimeter to spray all the surfaces where spiders build webs. The Pro-Spray Outdoor Perimeter with its 1m spray wand allows eaves to be reached safely.
Pro-Spray Crawling aerosol can also be used for the direct spray of the occasional spider invader. It is also ideal for spot treatments into crack and crevices, with its extendable nozzle and ability to spray upside down.