Bug survival mode

Yesterday, the NRT went on an awesome bug hunt to find all sorts of little critters creeping along the ground. As we walked around the trails, we were surrounded by the hustle and bustle of animals preparing for the winter. Squirrels and chipmunks were running around with acorns and hickory nuts, and flocks of birds were gathering in large groups for their long journeys south. This made me think, "what will all the bugs do?" Surely these ectothermic invertebrates ​need some kind of defense against the harsh cold temperatures. If they can't survive the winter, how do populations continue year after year?

After a little bit of digging, I became amazed at the different ways that bugs are able to survive extreme temperatures. Some of their adaptations were ones that I am familiar with, such as migration, but I was shocked to learn about insect antifreeze and even group cooperation to make it to the following spring. Below are a few of the different ways insects are able to make it through the winter!

Ectothermic:
An animal that is not able to produce its own body heat. They use heat energy from the sun to power their bodies.

Invertebrates:
Animals that lack backbones

Diapause​

This was a new one for me, but I was happy to learn about it. Diapause is an extended period of no growth or development and it is essentially the ability to freeze in place and then unfreeze again in response to environmental cues. Interestingly, the state of diapause is triggered by day length and not actually by the cooler weather that comes with the winter. As the days get shorter and there is less sunlight, a bugs body will tell it to start slowing down. The invasive Emerald  Ash Borer will enter a state of diapause during the winter and will remain completely inactive without moving and even eating under tree bark for many months at a time. Once the days begin to get long enough indicating spring is approaching, the extended amounts of sunlight will trigger the beetles to exit this state of dormancy.

Antifreeze

Yes, you read that correctly, some animals have natural antifreeze in their bodies! It's not exactly like the antifreeze that we put in our windshield wiper fluid, but it certainly serves the same purpose. The antifreeze that is found throughout some insects is a variety of different compounds that are also known as cryoprotectants. Cryo- meaning involving or producing cold and -protectants meaning providing protection, so cold protection or protection from the cold. 

One of New England's fall favorites, the Woolley Bear Caterpillar, uses cryoprotectants to shield it from the cold winters. These caterpillars can stay active into the fall, when many other insects begin to slow down. Because of their ability to produce antifreeze, these caterpillars don't need to find somewhere to overwinter and will usually stay hidden under leaf litter. They do become essentially immobile, but their bodies are not harmed by the extreme cooling temperatures. Woolley Bear caterpillars are able to stay unfrozen in temperatures as low as -8 degrees Celsius, or 17 degrees Fahrenheit!

Migration

Just like many other animals, billions of insects take to the sky during the changing of the seasons to travel to warmer climates and follow their food! One of the more well-known insect migrators is the Monarch butterfly, who can fly up to 3,000 miles each fall to their overwintering grounds of central Mexico. Monarch migration is currently in full swing, and if you come by Sheep Pasture in the next couple of weeks, be sure to explore the garden in front of our offices! The few butterfly bushes we have left have been a welcome stop-over site for these autumn travelers.

Monarchs are not the only insects that participate in cyclical migrations, many flies and even lady beetles have similar habits. Because of their small size and ability to go unnoticed most of the time, it can be difficult to track insect migration. Even so, scientists have observed a couple of interesting anomalies in the past few years indicating that insect migration may be more common than we think.

One of these anomalies was a cloud reported by the National Weather Service in San Diego, CA last year. The weather station was confused by what looked like a giant rain cloud on their radars but with no rain in sight. The radar was picking up on millions of "droplets" 5,000 feet in the air. Aside from this strange radar image, the area where the cloud was being seen seemed to have nothing out of the ordinary going on. That being said, a couple of people investigating the area did notice an uptick in lady bug activity and although it was never confirmed, much research has gone into whether or not millions of lady bugs might be migrating all at once 5,000 miles in the sky. Even if it wasn't lady bugs, it was certainly something of similar size moving in a uniform pattern across the night sky and opens the eyes to something that needs to be explored more - mass insect migration!

... And more!

Bugs are by far the most diverse animals on the planet and can be found on every single continent including Antarctica! This means that they have to have some incredible adaptations to defeat the cold weather. We talked about some of them above, but there are many more ways these little critters escape and even thrive in the cold weather. Some of these other methods include huddling together for warmth, digging below the frost line, laying eggs that can survive the cold weather before dying, and finding shelter in man-made buildings and structures.