Tilt your head back on a warm sunny day. Look just above the Ocean Spray and Nootka Rose bushes. What do you see? Turn your gaze down, peer at the tops of flowerheads, investigate the soil. What do you see? What don’t you see? They are everywhere and they have been for hundreds of millions of years: Insects!
At any given moment there are estimated to be ten quintillion (10,000,000,000,000,000,000) insects roaming the planet. Insects are often tiny in size, but mighty in their impacts on ecosystems and human societies.
Insects are more than just pollinators; they are clean-up crews for waste (decomposers), food for an abundance of wildlife, dispersers of seeds and much more. Our six-legged friends are also valuable to human society. Insects are the heavy lifters in the pollination of one of every three bites of our food. They are a direct food source themselves for around two billion humans also. So, how do they survive the winter?
Different insects have different strategies for surviving the colder months, and many don’t survive, they die. Insects are ectotherms, meaning that like reptiles, they derive their heat from the outside environment. Because of this, it can be very tricky for insects to stay warm in the winter.
Bagworms, for example, generally do not survive the winter, but females lay their eggs in brown-coloured pouches that survive overwinter and hatch the following spring. Many insects’ eggs survive over winter through diapause. Diapause is when the animal stops development for a period and then begins again in response to an environmental cue (such as light, or warmth).
Like bagworms, dragonfly adults lay eggs before the winter and adults often die. But that is not the only way this species survives the winter. Dragonfly juveniles (also known as nymphs or naiads) live in freshwater and can survive the winter too! They either stay active, especially in warmer places like Southern Vancouver Island, or they can enter diapause. If the nymphs stay active, they have the advantage of eating and growing throughout the season; however, they have the disadvantage of being a potential snack for fish!
Some types of dragonflies, and many other species of insects have a different method completely, … they migrate. Migration is a tactic of survival used by many animals in which they move away for a period, often to find warmth or food as seasons change.
Insects that migrate include some types of butterflies, moths, true bugs and beetles. The most impressive insect migration might be that of the monarch butterflies which can migrate 4,000 km to overwinter in the warmth of Mexico. Many insects migrate one way, lay eggs, die and their hatchlings make the migration back to their homelands.
Another unique method of winter survival, and a less “natural” one is invasion. Organisms that were brought to a place because of human activity and are causing negative effects on the environment, human health or the economy are called invasive species. Unfortunately, there are several invasive insects spreading throughout British Columbia.
The ways in which insects survive winter are fascinating and vast. Some methods are as specialized as having antifreeze proteins that stop them from freezing overwinter. Others can control what parts of their bodies freeze and keep vital organs thawed in the coldest months. Their unique adaptations to winter go on and on. They are impressive, and despite their size, excel in survival. Unfortunately, insects are largely threatened globally. Over 40 percent of insect species are at risk of extinction.
Want to be an ally to our tiny neighbours? Here are three calls to action to protect insects:
1. If you must use them, use ecofriendly pesticides: Using harmful pesticides can kill terrestrial wildlife and leach into waterways, causing algal blooms and harming freshwater invertebrates like dragonflies.
2. Rewild your lawn: Planting native species and adding dead wood to your yard can make it an oasis for pollinators and many other native species. You can learn more here: crd.bc.ca/education/natural-gardening.
3. Protect and restore ecosystems: Vote for nature when you can, and volunteer with local organizations to restore native habitat!
