Spiders are easy to kill one at a time and hard to keep away, because the reason they are on your house is usually still there: food, shelter and a steady supply of new arrivals from the garden. Getting rid of them for good means dealing with all three, and doing it at the right time of year.
This guide covers when spiders build up and why, when to spray, which products and home remedies are worth using, and when a professional treatment makes more sense than doing it yourself. If you would rather skip straight to it, professional spider spraying in Auckland is covered on our service page.
Why you suddenly have so many spiders
Usually it is the season. Spider numbers rise through the warmer months along with the insects they eat, and from late summer into autumn many male spiders mature and leave their webs to look for females, which brings them indoors. Te Papa's spider expert describes this late-summer wandering as the time people notice spiders most. New lights, clutter and a flush of insects can add to it.
Four things decide how many spiders a house carries:
- Season. Many spiders overwinter as eggs or small juveniles and grow through spring and summer. By late summer they are adult and obvious, and the males are on the move.
- Food. Outdoor lights, gardens, compost and bins draw insects, and insects draw spiders. A house with a lit porch beside a garden is a feeding station.
- Shelter. Eaves, window frames, gaps behind cladding, stacked timber, garages and sheds all give spiders somewhere to build and hide.
- Supply. Bush-edge and coastal sections have a constant supply of new spiders arriving from outside, which is why the same treatment lasts longer in the middle of a suburb.
The best time to spray for spiders in NZ
Late summer is the most useful time for an exterior spray, before the autumn build-up, with a second treatment in spring if webs return quickly. On the day, choose dry, still weather with no rain forecast, since product labels ask for anything from six to 24 hours dry. We prefer the morning or late afternoon to hot midday sun, and hold off brushing down webs for a couple of days.
What's the worst month for spiders?
In Auckland most people notice spiders most from about February to April, when adult spiders are at their largest and wandering males come indoors. White-tails, vagrant spiders and tunnelwebs are the ones most often found inside at that time of year. A treatment already in place by February meets them at the walls, rather than after they have come in.
Why the timing of a residual matters
A residual spray keeps working after it dries, but not forever, and it works best on surfaces spiders walk over and build on. Applied in late summer, it covers the months when spiders are most active around the house. Applied in winter, much of its life is spent when there is little to control. Leaving webs in place for a day or two after spraying means the spiders cross the treated surface when they come out.
What actually works to get rid of spiders
A combination works; no single product does. Treat the outside surfaces spiders use with a residual spray, remove webs and egg sacs, vacuum spiders and webs indoors, seal the gaps they come through, change the outdoor lighting that feeds them, and clear the clutter they shelter in. Each step makes the others last longer.
Residual spray on the outside
Eaves and soffits, window and door frames, vents, fences, decks, pergolas and the garage. These are where webs are built and where insects land.
Remove webs and egg sacs
Brush or hose webs off a couple of days after spraying, and take down the round silk egg sacs in corners and eaves, each of which can hold dozens of eggs.
Vacuum indoors
Vacuum spiders, webs and egg sacs from ceiling corners, behind furniture and under beds, then empty the vacuum outside.
Seal the gaps
Door seals, torn fly screens, gaps around window frames and where pipes and cables enter the house.
Change the lights
Insects are drawn most to bright white and bluish light. Warm yellow outdoor bulbs, motion sensors and lights switched off when not needed all mean fewer insects, and fewer spiders waiting for them.
Declutter the garage and sheds
Boxes, stacked timber and stored gear are ideal shelter. Sticky traps along the walls show you where spiders are moving and catch a few along the way.
What is the best way to get rid of a spider infestation?
Treat it as a house problem, not a spider problem. Work around the outside first: every eave, soffit, window frame and door, then the fences, deck and garage. Clear webs and egg sacs from the same places, then move inside to the ceiling corners, behind furniture and the garage. Finally, fix what drew them: the lights, the clutter and the gaps. Doing it in that order, in late summer, is what stops the webs coming straight back.
Egg sacs
Round or lens-shaped silk egg sacs in the corners of eaves, window frames, garages and sheds are the next generation, wrapped in protective silk. The surest way to deal with them is to remove them by hand or with a vacuum cleaner and put them in the bin. Check again in spring, when many spiders produce new ones.
Spider sprays in NZ: what to look for
For spiders on and around the house, a residual surface spray is the product type that works. It dries onto eaves, frames and walls and keeps affecting spiders that cross it. Bug bombs and foggers kill what they reach in a closed space such as a garage, but do not treat the outside walls. Dusts are for voids. Sticky traps catch rather than prevent. Follow the label exactly.
Many residual sprays sold in New Zealand are based on pyrethroids, synthetic relatives of the natural insecticide pyrethrin. Products people often search for include Wet & Forget's Miss Muffet's Revenge and Kiwicare's NO Spiders range. Both are residual surface sprays, and the same rules apply to them as to any other: the label says where they can be used, how much, and how long to keep people and pets away.
What is the most effective spider killer?
For a spider you can see, a vacuum cleaner or a direct hit with a household insect spray. For spiders you cannot see, a residual spray on the surfaces they use. University of California pest specialists make the point that spraying alone gives only temporary control unless it goes with removing webs, clutter and entry points, and that matches what we see. The EPA's advice for any insecticide at home is to use the least you need, exactly as labelled.
Smells and home remedies: what the evidence says
Peppermint oil, vinegar, citrus peel, eucalyptus and conkers are all widely recommended online for keeping spiders away. We are not aware of good evidence that any of them keeps spiders off a house for more than a short time. As deterrents, they are cheap to try and unlikely to hurt, but do not expect them to stop webs coming back.
The best homemade spider repellent is not a spray at all. It is a broom, a vacuum cleaner, a tube of sealant and a change of light bulb. Those deal with the web, the spider, the way in and the food supply, which is what actually decides whether spiders stay.
Can you get rid of spiders 100%?
No, and you would not want to. Spiders are among the most effective predators of flies, moths and mosquitoes around a house, and new ones arrive from the garden all the time. A realistic goal is a house with no webs building up on the outside, few spiders indoors, and no white-tails hunting through a supply of house spiders. That is achievable, and it lasts if the causes are dealt with.
"Permanently" is the wrong word for any spider treatment. The residual wears off, spiders keep arriving, and the insects that feed them come back each summer. What makes the result last is the combination: fewer insects, fewer hiding places, sealed gaps, and a treatment renewed once or twice a year.
Spiders and flies are linked
Reduce the insects around your house and you reduce the spiders. House spiders feed on blowflies, house flies and moths, and they build their webs where those insects land: around lights, windows and doors. A house with bins beside the back door, uncovered compost and a bright porch light is supplying the spiders' food, and the spiders will keep coming back to eat it.
So the fly side of the job is part of the spider side. Lids on bins, compost managed properly, pet waste picked up and fly screens on the windows you open all help. Our guide to flies in the house covers each type of fly and where it breeds.
DIY or professional spider treatment?
DIY is usually enough for a single-storey house in a suburban street, where you can safely reach the eaves and webs are a mild nuisance. A professional exterior and interior treatment makes more sense for two-storey homes, bush-edge and coastal sections, houses where webs return within weeks, and anywhere white-tails keep turning up indoors. It is also safer than working from a ladder with a sprayer.
A professional treatment differs mainly in reach and thoroughness: every eave, soffit and frame, the garage and the roof void entry points, with products and equipment that put the residual where it is needed. See what spider spraying costs in Auckland, or call 09 925 0448 for a price on your house.
Frequently asked questions
How long does spider spray last?
It depends on the product, the surface and the weather. Manufacturers of retail residual sprays claim anything from a few months to a year on surfaces sheltered from rain, such as eaves and soffits, and much less on exposed walls. Rain, strong sun, water-blasting and repainting all shorten it, which is why exposed walls and fences lose protection first and why many homes are re-treated once or twice a year.
Is it safe to spray for spiders with pets?
Generally yes, if you follow the label. Keep pets and children away while you spray and until the surface is dry, usually a few hours, cover or move pet food and water bowls, and cover fish tanks if you treat indoors. Cats are more sensitive than dogs to some insecticides, so read the label carefully. Our guide to pest control safety around pets and children covers the detail.
Should I spray inside or outside?
Mostly outside. The webs and most of the spiders are on the outside of the house, and a barrier there stops spiders and the insects they eat from coming in. Inside, keep treatment targeted: the corners, skirtings and gaps where spiders get in, and the garage. Broadcast spraying of living areas adds exposure without adding much control.
Do ultrasonic spider repellers work?
We are not aware of any good independent evidence that plug-in ultrasonic devices repel spiders, and we do not recommend spending money on them. If you have one and still have webs, that is your answer. Money spent on sealing gaps, changing outdoor bulbs and an exterior treatment does more.
What is a spider's natural enemy?
Other spiders, birds and wasps. White-tails specialise in eating house spiders, daddy long-legs catch white-tails, and spider-hunting wasps paralyse tunnelwebs and vagrant spiders to feed their young. Lizards and birds take plenty in the garden. None of these will clear a house, but they are one reason not to spray the whole garden. Our guide to white-tail spiders explains their taste for house spiders.
Do spiders come inside more when it's cold or wet?
The season matters more than the weather. The spiders that turn up indoors from late summer into autumn are mostly males that have matured and left their webs to find females, and some wandering spiders dry out and go looking for moisture once they are inside. A spell of wet weather can bring ground spiders to doorways, but it is the time of year that drives most of what you see.
- Te Papa blog — Wellington's summer spiders (why numbers rise)
- Te Papa — What spider is that?
- EPA New Zealand — insecticides and pesticides at home
- UC IPM (University of California) — Spiders: pest notes
- UNH Extension — Bug-friendlier outdoor lighting
- Kiwicare — Spiders (product label and application advice)
- Pest Management Association of New Zealand — Spiders
- Manaaki Whenua Landcare Research — identification
