Yukon insects outsmart northern climate
A few years ago, when Randy Lamb was working for Yukon Agriculture Branch, he got a call from a Whitehorse business owner with a bug problem.
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One of the Yukon's overwintering insects, a bumblebee, holds pride of place in Randy Lamb's insect collection.
(photo: Randy Lamb)
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Every morning when his employees came to work, they found scores of red bugs, a little smaller than ladybugs, in the entry way of the business. When squished, the bugs leaked red fluid. The business owner was sure it was blood and the bugs were feeding off his employees.
The reality was less alarming and more interesting, says Lamb, who now works for another branch of Yukon Environment but retains his fascination with insects.
The red bugs were an unusually large kind of aphid, and the red was just the aphids' bodily fluids, not the blood of innocent employees.
The red aphids are unusual in more than size. Like the ladybugs they resemble slightly, they appear to overwinter as adults. To survive the cold of a Yukon winter, they move into cracks in trees, rock faces, clay cliffs, and buildings, preferably facing south.
In late summer and early fall, both species gravitate to warm surfaces and start moving into cracks. In some places further south, ladybugs have been known to congregate in huge numbers at suitable overwintering sites, just as garter snakes do.
The Whitehorse business with the aphid invasion faced south and had plenty of warm, inviting crevices in its siding and entry way. The aphids were just looking for a winter home, says Lamb.
Although most insects survive the cold weather in the relatively tough form of eggs or pupae, quite a few, like ladybugs and the red aphids, have developed ways to overwinter as adults or larvae.
The large, furry bumblebees that trundle clumsily around early spring flowers have probably spent the winter buried in the leaf litter on the forest floor, says Lamb. The large wasps that plagued the southern Yukon this spring also overwintered as adults, probably in much the same circumstances.
"It's minimal protection. They seem to nest under anything that's available."
In both cases, the individuals that come out from the insulating leaves in spring are queens who set out in search of locations for new hives. The other members of the bee and wasp colonies only live a single season.
Lamb speculates that the large number of wasps and bees that emerged this spring survived thanks to a series of late falls and warm winters.
"We've had some pretty interesting seasonal trends lately that have really thrown things for a whack."
Some insects overwinter as larvae rather than adults. Long-horned, or "pincher", beetles are one Yukon example. They're woodboring beetles that eat their way through freshly cut pine logs or fallen trees.
"Sometimes you can hear them munching when you walk by a pile of pine logs," says Lamb.
The pincher beetles can survive more than one winter as larvae before transforming into adults.
One of the more spectacular insects to overwinter in larval form, says Lamb, is the giant predacious diving beetle. The large water beetle is a fierce predator that will attack prey even larger than itself. Adults often show up in puddles in May when they're flying in search of new water bodies to lay their eggs.
However, the adults are newcomers on the scene. The insects survive through several winters as larvae called water tigers.
"The larvae are huge. They eat things as large as minnows," says Lamb. "They're really intimidating. They'll even grab fingers if you give them a chance."
- For more information about other insect adaptations to the cold, check out Your Yukon column #63 – "Insect Antifreeze."
- For information about Yukon insects, contact the Yukon Department of Environment at (867) 667-5652.
