Article posted on May 15, 2018

How Does Rain Affect Pest Control Treatments?

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Brisbane Resident, Justin asks

“We’ve just had pest control done at our house and it looks like it’s going to start raining. Should we be worried? Will the pesticides be washed away? What should we do?”


danny kelly pest imageWe get this question quite a lot here at Pest-Ex from concerned residents for obvious reasons.

Needless to say, if you’ve just spent a couple of hundred dollars on having your house or property sprayed for bugs, the last thing you need is to have everything washed away in a big down pour.

In most cases, callers ask us –

  • Can you spray pesticides in the rain?
  • Will the rain wash the treatment away?
  • Should we cancel our appointment or not?

Here’s a complete answer to Justin’s question, along with some key pointers to help you out.

Can a big downpour of rain affect pest control?

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If you’ve just had the exterior of your house sprayed and it rains not long afterwards, chances are it won’t affect the treatment whatsoever. There’s 2 reasons for this –

  1. Most homes have eaves and guttering that overhang wall edges – so, unless the rain is coming in with 80mph wind gusts and blowing directly against the walls, it’s not going to have any affect
  2. When we treat the exterior of the home or business, we ensure that we don’t spray wet surfaces. This is because the pesticides need to “bind” with the area of which its being applied. In other words – we don’t spray a wet wall. If it’s been raining heavily for hours on end before performing the treatment then it’s probably not a good time to spray. The pesticide needs to bind with the surface for it to take affect.

Should you cancel your appointment?

There will be some exceptions to the rule but for most cases, you won’t need to reschedule your appointment. Obviously if you’re only having the inside of the property treated you won’t need to, but there are a few things you need to be aware of if it’s been raining and you intend on having the outside done.

Firstly, many of the insecticides that we use are insoluble and won’t be washed away by rainfall, however if it’s been raining heavily for days on end, and the weather only looks to be getting worse, then it might be best to reschedule.

Secondly, often when it’s wet and the ground’s soft, most pests, especially ants – they’ll actually come out from the ground because they’re looking to escape the moisture from their nests. This can result in the treatment being more effective because we can not only hit the pests directly but also because the pesticide granules dissolve and are absorbed into the ground, killing off more pests beneath the surface. Infact some treatments require the product to be wet in order for the toxins to be released.

We will often advise the customer gets out into the yard within the first week or two, and water the perimeter of the property in order to activate the pesticides – especially if it’s been considerably dry.

So, for some treatments, if it’s going on wet ground, it’s even more effective.

In Summary

When treating the outside of the home, especially when spraying for spiders etc, we apply a thin film of insecticide spray – usually Bi-Flex Aqua Low Odour – . The product dries within 10 minutes, so if it rains half an hour later, it won’t affect the treatment.

Any treatments performed at ground level, as with granular insecticides, we’re usually treating for ants or cockroaches, especially in the lawns. This type of product works best if it’s wet. Again we’ll usually tell the customer, “If it’s not wet, they’ve got to get out there and give it a bit of a hose.”

So, in summary it really depends on the type of treatment as to whether or not the treatment might need to be rescheduled or affected in any way, but typically this isn’t likely.

Customers should note that no reputable pest control company should be applying pesticides of any sort against wet surfaces. We don’t for the reasons mentioned above. Of course if you have any concerns get in touch with us and we’ll gladly help.

Ready to work with Pest-Ex?

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Pest-Ex have been providing pest control services throughout Brisbane, the Gold Coast, Tweed Heads and Logan City since 2006. We have performed thousands of pest inspections and have more than 7,000 happy customers.

We’re also –

  • Fully insured and licensed
  • Our pest controllers are among the most experienced and qualified in the pest control industry
  • We only use environmentally friendly products, and are dedicated to providing pest control solutions that are safe for your family and pets
  • We are flexible, and can work in residential, commercial and industrial properties

Talk to Pest Ex today for all your pest management and protection services – we look forward to hearing from you!



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