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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?

rain wash away pesticides image

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!

Our focus areas include Brisbane, Gold Coast, Tweet Heads & Logan.



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Kent Bailey
11 months ago
Just had my home barrier treatment for termites by Pest Ex. In every way a brilliant job and fantastic friendly service unlike...read more anything else I have struck on the Gold Coast. This is a very professional company and every person involved was excellent in every way. Strongly recommend them to all who read this review because you won't do better.
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Christie McCabe
a year ago
On time. Efficient. Friendly. Informative. Well priced. Our experience with Pest-Ex was easy from the moment Reception answered our call. Our routine...read more pest inspection could be done the next day (a Saturday which is most convenient for full time workers). Karl arrived at 7am with a smile to complete the service and carried out the work efficiently informing us of the process where required. Thanks team.
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Chris Burt
2 years ago
Very professional and able to identify our pest problem on the spot. Was on time and great communication with admin girls via...read more phone. Very conscious of keeping our pet safe after the treatment which was a classy touch. Highly recommend!
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6 months ago
Great people and always helpful and providing a good service.
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Lorrie Cruickshanks
a year ago
Thank you to Garyn who first identified the issues, he was extremely thorough and prompt and then to John and Janine and...read more the team who treated and area and placed the baits. The process was fully explained and they were extremely courteous and very professional. Thank you to all the team. The office also kept us up to date with when their representatives would be visiting and this is very much appreciated. Great work.
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Donna Hamerton
a year ago
After reading reviews, I'm glad that I chose Pest-Ex. Maria in the office was more than understanding to accommodate me and times....read more I was able to get a booking the same day I made the enquiry. Garyn my technician was even able to come earlier. When he arrived he was happy to explain everything that was going to happen and how to work around my pets and children. Need pest control done - hire these guys.
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Phoebe Worth
2 years ago
Impressed with the service. The technician Steve was on time, friendly and thorough - you could tell he was not rushing the...read more job. Will be using Pest-Ex again. Thanks guys!
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Mickey Ketch
a year ago
This company actually investigates the problem instead of just spraying your place and leaving. Very HIGH knowledge and experience in what they...read more do. They took the time to investigate the cause, the source of the problem and elimnated it completely which included going through every cupboard, cracks hiding spots the lot. We had a cochroach problem in our apartment for 3 months and we had 4 different companies come out and NONE of them investigated they only sprayed. After we called PestEx, Mr. Phillips was very knowledgeable and experienced eliminating our problem entirely. We also use PestEx in our shop and both Mr Phillips and Marty are EXCELLENT in resolving and maintaining pest problems. HIGHLY RECOMMEND PEST EX. BEST I'VE SEEN IN QUEENSLAND.