As the BBQ season starts to kick in, a lot of houseowners are looking at sprucing up the outside of their homes, by
washing exterior walls and getting rid of those nasty looking spiderwebs.
Reuben from EcoSan, an Auckland-based pest control company, has been getting calls from people who want their houses washed and any
spiders sent packing at the same time.
His response to such requests is simple. Get rid of the spiders first.
“A lot of people are under the impression that water blasting and soft washing will get rid of spiders,” he says.
That’s true up to a point. But spiders, particularly during daylight, will hide in concealed holes and cracks, tucked
safely away from the spray.
Then there’s the fact that spiders are quite hardy critters.
“Chlorine products and antimicrobials that are used for controlling mould and moss may kill more sensitive spiders, but
many will resist the chemicals. Even spider eggs will remain unharmed.”
Insects also have a low respiratory rate so they can survive underwater for a long time.
The recommended strategy for eradicating spider populations on the exterior of houses and buildings is to use residual
insecticides.
“These residual insecticides don’t need to be toxic to family and pets to be effective against spiders,” Reuben says.
So when is the best time to strike?Treat two weeks before washing
EcoSans recommends treating a house exterior with a residual insecticide two weeks before it’s due to be washed.
“We find this gets the most effective results,” Reuben says. “If a spider control treatment is applied after the house
is washed, the spiders may begin to make webs reversing the work of the house washing.” He goes on to add that the
chlorines and antimicrobial residuals from the house wash will shorten the life of an insecticide.
Spiders also tend to make nests within timber, aluminium and PVC joinery, “Residual insecticide needs to be liberally
applied around frames and entry points to properly control these spiders. If the building has recently been washed, the
insecticide residue could ruin the clean finish of thew windows.”Controlling spiders after a house wash
Applying residual insecticide a minimum of two weeks after a house wash is a good way of minimizing spider numbers. “The
after-wash spray will kill off any remaining spiders plus prevent new spiders from coming along to create webs,” Reuben
explains.
Spiders on exterior cladding make even the cleanest joinery look messy. Following the treat step process of treat, wash
then treat again will keep a home spider free and looking better, longer.