As winter thaws into spring, insect life is emerging in Southeast Alaska. We spoke with Juneau naturalist Bob Armstrong to find out what the bugs are doing.
Temperatures are climbing up from freezing. Two weeks ago a caddisfly was reportedly seen circling around a Haines light bulb. A few days ago a large mosquito was observed landing on a pile of wood. The insects of the northern Lynn Canal are coming out.
Bob Armstrong was a biologist for Fish and Game who retired decades ago. He has since turned his attention to the insects around his home in Juneau. Armstrong says some of the early insects we are seeing have spent the winter in their adult form.
Armstrong: “Caddisflies, there are some that overwinter under the bark of trees as an adult and then when spring arrives, they go into their mating ritual. And there is another one called a snow midge that comes out in midwinter and its sole purpose is for mating. And they run about on the ice and mate with one another. They are very tiny, look like a little fly.”
Armstrong says the mourning cloak butterflies also overwinter as adults. They have dark red wings with a yellow edge and are the first butterflies out in the spring.
Some spiders also stay active throughout the winter.
Armstrong: “There is quite a few that come out on the snow to hunt. There are insects that come out and run about on the snow and they go after them in winter.”
Armstrong says spiders tolerate frost, but only to a certain point.
Armstrong: “And so once they do their hunting they have to go back down into the ground below the snow. And from what I understand if they are out and about and we get some rain or things start to melt a little bit and then the temperature plummets, they can’t go back down into the ground, and they end up freezing and dying.”
Armstrong says willow catkins, the budding flower clusters on willow branches, are already attracting a lot of bugs near his home in Juneau
Armstrong: “And there is one fascinating insect called the willow weevil, which is a beetle with a big snout. And they mate on the willow catkins, and then the female lays her eggs on them. And then the larva eats the inside of the catkin.”
That is just one link in the food chain. Armstrong says some birds have learned to recognize an infested catkin by its curved shape. He has observed birds feasting on catkins full of larvae.
Other iconic bugs are feeding on the willows. The spotted tussock moth spends its youth as a black and yellow caterpillar known as the wooly bear.
Armstrong: “They are toxic. So birds won’t eat the caterpillars. But when they go into their cocoons they lose that toxicity. Chickadees have learned to target them and eat the larva inside, so that is why have learned to build their cocoons under rocks where other creatures can’t get to them.”
As adults, the moths make a clicking noise that helps prevent them from being eaten by bats. The clicking acts like a warning flag. Armstrong says there is some evidence the clicking interferes with bat sonars.
Armstrong: “But probably the most important insect in Alaska is the queen bumblebee.”
Armstrong says those important pollinators overwinter by themselves in the ground. In the spring they have to rush to eat enough food to be able to lay eggs.
Armstrong: “There is a plant called an early blueberry that blossoms probably any day now. And you’ll see quite a few bumblebees coming to the flowers and feeding on them. At this time of year, they would be the queen bumblebee.”
Blowflies are also pollinators. Those metallic-looking flies spend part of their youth as maggots in salmon carcasses.
Armstrong: “Then the maggots maybe go through up to six stages and then burrow into the ground and pupate and emerge as adults. And I read one report where they determined they were more important than bumblebees.”
After watching insects closely for many years, Armstrong says he sees their individual personalities.
Armstrong: “Most interesting is I did quite a bit of work with crab spiders.”
These spiders do not weave a web. They hunt on flowers. Bumblebees are a prized catch for the females because that gives them enough food and energy to lay their eggs.
Armstrong: “It’s just fascinating to watch the different bumblebees that will approach a flower with a crab spider on it. Some of them will hover there looking, and going around the flower and so on and zoom away, and some others will just land on the flower and feed and get caught.”
Armstrong says nowadays he sees fewer insects than in past years. Studies around the world confirm this observation.
Armstrong: “There is quite a bit of evidence worldwide that a lot of insects are declining because of climate change. Almost everywhere they looked there’s been up to a 70% decline in insects. So it’s pretty sad what is happening.”
A friend of Armstrong’s in Gustavus also has observed a decline in bumblebees. He tied it to the decline in willows, an important food source. He says a large moose population has been feeding on the willow, reducing their number.
Armstrong: “Probably what is needed is to eliminate the wolf predator control program, so it will help control the moose, so the bumblebees will survive better.”
Armstrong says life is complicated, and humans often get it wrong. Maybe observing our insect neighbors more closely can help us get it right.
