A hot summer means ants and wasps could make picnics more precarious, and pests could take bigger bite out of trees.
The latter is of concern to City of Red Deer arborists, who are on the look-out for signs of tree damage after last week’s prolonged heat wave and more warm weather on the way this weekend.
Insect life cycles speed up in hot weather, meaning more generations of bugs can develop in the summer season.
While City of Red Deer urban forester Susan Katzell hasn’t noticed any major infestations yet, she has seen plenty of signs of European elm scale, fire blight, spruce sawfly, ash bark beetles and other tree pests.
On Tuesday, city arborist Paige Graham was busy pruning ash trees near Gaetz Avenue and 74th Street that showed signs of ash bark beetles — dark rings and circular pin-hole bores that can weaken branches. These insects can kill whole trees, but it’s rare.
A more insidious elm-eating pest is the emerald ash borer. Several triangular prism traps have been hung in Red Deer trees as a surveillance measure for these insects, which Katzell said have “devastated”green ash trees across Ontario and in Winnipeg.
So far, no emerald ash borers have made their way to Alberta. And that’s a relief to Katzell since most of the downtown trees that grow from hard grates on Ross Street are ash trees.
“They are very valuable-looking trees,” she explained. “If they all died it would change the aesthetics of the city…
“Our hard winters aren’t enough to kill these bugs,” added Katzell. She tells Red Deerians who are driving to Manitoba or Ontario this summer: Don’t bring back firewood as it could contain these insects.
A pest that’s made a presence in the city is European elm scale — Katzell said gardeners should watch for tell-tale signs, including yellowing leaves and sticky “honeydew” (insect excrement left on the bark). It often gets covered in blackened mould.
To minimize the effects of elm scale, keep elm trees well watered and healthy. Katzell advises pruning out any dead or dying wood between October 1 and March 31 only. Dormant oil and foliar sprays can be used to treat infested trees. She said gardeners should consult with an arborist.
Most bug populations are cyclical, “but heat speeds up their development,” increasing numbers that hatch over the summer months, said Ken Lehman, ecological services operations co-ordinator for the City of Red Deer.
Lehman believes understanding bugs is a first step towards dealing with them. For instance, he said yellowjacket wasps are looking to create a nest this time of year, so putting up a nest facsimile (stuff a paper lunch bag with crumbled paper and hang it in a tree) will deter them from building in your yard because they are territorial.
When wasps hatch in late summer and plague outdoor diners, he advises not swatting at them because wasps will be threatened and sting you. Since they are after sugar as well as protein, leaving a bit of sugary drink in a narrow neck bottle can act as a wasp trap.
But Lehman stresses there’s a place for everything in the ecosystem. “You don’t want to get rid of all of the wasps,” he said, because they eat ants — which are also copious this summer.