Why are spiders coming inside? Spider season in SA

Spiders come inside in spring and early summer because the warmer weather wakes everything up at once. There are more insects about, which means more food, many house spiders reach maturity over the warm months and go looking for a mate, and hunting spiders follow their prey indoors. Most of the spiders you find inside are harmless, and a few simple habits plus an inside-and-out treatment keep them down.

Around the Barossa and Adelaide it usually shows up as small spiders on walls and ceilings, fresh webs in the window frames and the odd big one in the bath or the laundry. It’s one of the most common things people ring us about once the weather turns, so here’s what you’re likely looking at and what to do about it.

Which spiders come inside in South Australia?

Black house spiders (window spiders). Dark, solid-looking spiders with a charcoal-grey abdomen and white markings. They build lacy, messy webs with a funnel-shaped retreat in window frames, wall crevices and around eaves. The Australian Museum notes they reach maturity in summer, when the males go searching for females. They are timid and bites are uncommon, though a bite can cause local pain and swelling.

Daddy long-legs. The thin, long-legged spiders hanging in ceiling corners, behind doors and in sheds. The popular story that they have the most potent venom of any spider has no scientific evidence behind it, according to the Australian Museum, and they are harmless to people. They will even kill and eat a redback.

White-tail spiders. Cigar-shaped, dark grey, with a white spot at the tip of the abdomen. White-tails don’t build webs to catch food. They wander at night hunting other spiders, and black house spiders are a favourite. That’s why they turn up indoors in the warmer months. Their bad reputation is mostly undeserved, as we explain in what the research says about white-tail bites.

Redbacks. Mostly an outdoor spider, in dry, sheltered spots like sheds, wood piles, under outdoor furniture and in meter boxes. They do sometimes end up in garages and outdoor toilets. Only the female’s bite is dangerous. See our guide to where redbacks hide and redback bite first aid.

Why you’re seeing more of them right now

It comes down to food and breeding. Warm days and nights bring out flies, moths and other insects, and spiders follow the food. Black house spiders mature over summer and the males leave their webs to find females. White-tails, in turn, follow the black house spiders. When researchers followed 130 confirmed white-tail bites for the Medical Journal of Australia, 95% happened indoors and most were in the warmer months, September to April. That lines up with what we see on the job: spider calls pick up as soon as spring arrives.

If it’s been a couple of years since your place was last treated, expect to notice the difference. The spiders that would have been knocked back outside have had time to build up, and more of them end up wandering in.

What you can do yourself

• Brush down webs regularly around window frames, eaves, door frames and the pergola. A broom on a long handle does the job.
• Check flyscreens for holes and fit or fix door seals, especially on laundry and back doors where gaps are common.
• Move wood piles, stacked pots and junk away from the walls of the house. These are exactly the dry, sheltered spots redbacks choose.
• Wear gloves in the garden and shed, and shake out boots, gloves and clothing that have been left outside or on the floor.
• Keep outside lights near doors switched off when you don't need them. Lights draw insects at night, and spiders build where the food is.

A can of surface spray from the supermarket kills the spider you hit and not much else. It won’t treat the eaves, the window frames or the nesting spots the next lot comes from.

Inside spray, outside spray, or both?

This is one of the most common questions we get when people ask for a quote. Most spiders live and build on the outside of the house, on eaves, window frames, fences and sheds, and the ones you find indoors have mostly walked in from there. So the outside treatment does a lot of the work.

But if you’re already seeing spiders on the walls and ceilings, webs in the cornices or small spiders around the bedrooms, the inside corners need treating too. That’s why our standard spider control treats the nesting and web areas inside and out in the same visit. Most customers fold it into an annual general pest treatment, so the ants and cockroaches are covered at the same time. If your place doesn’t need the inside done, we’ll tell you.

When it’s worth calling us

• Webs are back within days of brushing them down.
• You're finding spiders inside most nights, or in the kids' rooms.
• There are redbacks around play equipment, outdoor furniture or the clothesline.
• It's been more than a year since the last treatment and the numbers are climbing.

Tell Garry what you’re seeing on 0403 018 325 and he’ll give you honest advice and a free quote. We cover the Barossa Valley, Gawler and Adelaide suburbs.