A rising buzz: Edmonton wasp and ant populations might double because of extended warmth waves

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When a sustained record breaking heat wave took its toll on the Edmontonians, most of the beetle populations thrived in the arid conditions and are on the rise.

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Instead of taking the typical 20 days to develop, insect life cycles in hot conditions can shorten to a week and quickly double. Edmonton city pest expert Mike Jenkins said he expected populations of ants, flies and yellow vest wasps to thrive in this heat and, as a result, to be larger than in previous years.

“They thrive in hot and dry conditions, and their life cycles are all increasing, so they can actually double the size of the colony in that week,” Jenkins said. “Your metabolism depends on the outside temperature. The warmer it is, the faster your metabolism goes, and many of them actually thrive in warmer temperatures. That’s why you see a lot more insect activity in tropical conditions.”

Temperatures rose to the mid-30s range last week with very little rainfall, resulting in an extreme heat warning for the entire province.

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Although Jenkins expects more insects to be buzzing around the city due to the extreme heat, Jenkins said a limiting factor currently could be limited access to water resources due to the arid conditions. These bugs still have to forage for food and liquid resources, and Jenkins said if they can’t find them, they are more likely to become irritable and, in the case of wasps, more likely to sting.

But the limited deep-lying aquatic habitats will also reduce the chances of growth for mosquito populations, which Jenkins said would otherwise have developed rapidly due to the heat.

“The good news is that it’s so hot and dry right now that there are no temporary aquatic habitats,” he said. “These types of conditions are not conducive to large numbers of mosquitoes.”

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Population growth isn’t necessarily a bad thing, although it could cause more trouble for people depending on where you are, Jenkins said. But it depends on the type of species, Jenkins said, noting that species not native to Edmonton could cause more problems because they don’t have predators to control the population.

This applies to the elm scale, which has become a major nuisance among the elms in the city’s urban forest. Without predators, this white spongy insect thrives and could harm the trees it lives on if it sucks the sap from them. Jenkins said the city is actively working to reduce and control these populations by spraying an insecticide into the branches to target directly at the elm scales.

“They’re not native, they don’t have these natural enemies, and their numbers are increasing,” Jenkins said. “They are the ones who are potentially a greater threat to our urban forest, and that’s what we’re focusing on.”

To minimize the effects of elm shedding, residents are encouraged to keep elms well watered and healthy on private property, and only prune dead or dying wood between October and March.

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