Town of Okotoks crews are out this week spraying for Elm Scale.
A non-toxic horticultural oil is used to combat the insects, which attack elm trees in large numbers.
It's not to be confused with Dutch Elm Disease, which is not present in Alberta.
The prevention of Dutch Elm Disease is the reason behind strict rules around storing and transporting firewood, as well as the provincial pruning ban from April 1-September 30.
Elm Scale, on the other hand, is the name of insects that feed off of sap from trees.
Urban Forest Parks Technician with the town, Gordon White, says they can be a blight on trees in large numbers.
"The insect feeds on the leaves a little bit, but most of the damage comes from feeding off the twigs. If left unchecked, they can certainly cause branch dieback in trees and could potentially kill them."
Aside from the scale-like appearance that gives the insects their name, White says there are other ways to identify trees affected by Elm Scale.
"One of the key signs that your elm has elm scale is the bark starts turning black. That's the sooty mould that's growing on the sap that the insects excrete. It can build up on decks and cars and stuff. It can be a nuisance."
If a tree on your property has a build-up of the bugs, White says you don't necessarily need special oil or pesticides.
"If you blast them with a stream of cold water you can certainly remove some of them, I just caution people if you're using a pressure washer or something like that, don't strip the bark of the tree."
The town is asking residents to give crews plenty of room as they work and to watch for signage.