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Rethink pesticide applications and storage in hot locales and during extreme heat events.

July 1, 2022

Excessive heat can destroy the insecticides locked in your vehicle toolbox and make pesticide applications less effective, said pest control industry consultant Stoy Hedges


To achieve better results and reduce callbacks when temperatures are cranking, rethink how you apply and store pest control products.

Ask yourself: Where are the pests when it’s hot outside?

They’re probably not crawling on hot foundation walls and surfaces in full sun. Argentine ants, for instance, will avoid walking on surfaces that get hotter than 84 degrees Fahrenheit. Instead, they’ll trail along edges of patios and foundations that don’t get so warm, said Hedges.

It’s more effective to treat the cooler, shaded areas where the bugs are hiding during the day. This includes in foundation cracks and voids, behind vegetation growing along the foundation, in expansion joints, in the grass along sidewalk, on patio and foundation edges and under rocks and mulch. “You’ll have much better success,” said Hedges.

Ask yourself: Am I using the right product for the heat?

Extreme heat can affect the performance of some insecticides. “We do know that many pyrethroids are negatively affected. They become less active as the temperature rises. It stands to reason if it’s super hot, the insecticide will break down,” said Hedges.

That means your application won’t last as long. “You’re not going to get two to three months of residual on surfaces where the temperatures get really hot. Those areas will need to be retreated,” he said.

Ask yourself: Am I properly storing and transporting products in the heat?

High heat can affect the products on your service vehicle. It can melt glueboards. “A melted glueboard is a mess,” said Andrew Greess, president of Quality Equipment & Spray, a distributor and custom builder of spray equipment for the pest management and landscape industries.

Aerosol cans can explode when temperatures exceed 120 degrees Fahrenheit, concentrated insecticides are affected and baits and gel baits can be denatured by the heat.

“In fact, every label I’ve read says store in a cool, dry place,” said Hedges. This can be hard to do when the temperature is 115 degrees Fahrenheit in the desert Southwest. As such, some technicians use specially designated coolers to transport baits and fungus-based insecticides.

Use a thermometer to get an accurate measurement of heat in your vehicle toolbox. “It could be cooler; it could be a lot hotter. You just don’t know [until you measure it],” said Hedges. Try to park in the shade, and never transport pesticides in the cab of your vehicle, he added.

Ask yourself: How can I reduce the risk of rodent bait meltdown?

In the “Mallis Handbook of Pest Control,” rodentologist Dr. Robert Corrigan said rodent bait blocks are subject to “bait meltdown” in areas of the country with hot daytime temperatures, and especially in bait stations located along the south and west sides of buildings in these areas.

To reduce the risk of bait meltdown, he suggested using bait stations made of metal or high-density plastic, which dissipate the heat better than plastic stations. As well, substitute gray-colored stations for black ones, which get hotter in the sun. Other tips are to use vertical versus horizontal bait rods, insert bait blocks into resealable plastic baggies and clip the bags to the interior sides of the station. Also, make sheet metal covers to cover stations subject to intense sunlight. During the warmest months or in stations that get the hottest, consider using snap traps.