Tuesday, February 8, 2022

What's This Bug? The Ice Crawler.

A brown Ice Crawler on grey ice.
As I write this, winter storms are creating misery across huge portions of the US. There’s just so much snow and ice a person can take. But that is not the case with the Ice Crawler (aka Rock Crawler, Ice Bug) of the Grylloblattodea order. These critically endangered insects are small insects (about an inch) that live in cold and snowy mountainous places like ice fields, glaciers, subterranean lava tubes, and ice caves.

A female on a clump of ice in someone's hand. You an see her ovipostor at the rear of her body.
Ice Crawlers are only found in western North America and Canada and in northeast Asia. In these areas this plucky insect has carved out a place for itself where they have less risk of being preyed upon and are not competing with other insects. They thrive in temperatures that hover around the freezing mark, but they will freeze to death if it gets much lower. Conversely, temperatures much above that point will kill them as well. In fact, merely holding them in a warm hand too long can kill them. They have adapted to living on mountains as temperatures there tend to be more stable than in lower altitudes. And if it gets too cold, they will go underground or under the snow (an insect igloo). Their preferred temperature range is too cold for most insects; the ones that venture there quickly die. There are also fewer of the common predators (birds, small mammals) up there, but if one comes too close they will retreat into their underground lairs. In addition to all these adaptions, Ice Crawlers have adopted a nocturnal lifestyle to further enhance their survival chances.

A Mount Spokane Ice Crawler foraging in the ground.
If high altitude landscapes offer specific survival benefits for Ice Crawlers, they also offer little in the way of food. Ice Crawler has adapted to this in a very basic way – they’ll pretty much eat anything they come across. It is believed that they feed on aerial plankton, but they also scavenge under rocks for decaying plant
matter or mosses. Additionally, they will snap up any hapless flies or moths that made the fatal error of visiting the snowy realms. 

Ice Crawlers have an unusually long lifespan for an insect. Long lives are common amongst cold weather dwellers, and for the Ice Crawler it can take as much as 7 years to complete a life cycle from egg to adult. Add to that the year or so that an adult can live, and you got yourself the Methuselah of the insect world. 

Professor Sean Schoville at work on a mountaintop.
Unfortunately, all these adaptations that have allowed the Ice Crawler to survive in an environment that is inhospitable to most other living things is what is putting their species at risk for extinction. Just as amphibian health reflects the condition of the watery world they live in; Ice Crawlers reflect the ice that’s their home. As we lose ice to climate change, their numbers are falling. Scientists know that much, but there is still a lot to learn about these shy insects and the fear is that we are losing populations before we even know they existed. Luckily, we have some scientists who are willing to spend hours sitting on ice to get the needed data. Sean Schoville, a professor at the University of Wisconsin deserves a special shout-out .He has gone the extra mile (literally) to discover as much as he can about these little creatures. If you want to learn more about what he does, check out this fun article written by an adventurous man who joined him on an expedition (there are some great pictures). 

Submitted by Pam

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