When the cold winds of winter blow, we throw on our warmest coats and gather around the fire. But what about insects? While some species migrate to warmer places, most rely on extraordinary survival mechanisms to endure the brutal cold. One of the most remarkable is diapause—a dormancy period so powerful, it's like hitting the “pause” button on life itself.
Suspended animation isn’t just the stuff of science fiction; many insects masterfully employ it, dropping their biological functions to absurdly low levels when they sense harsh times ahead. Diapause is more than a slow-down—it’s a precisely timed biological response that halts development and drops metabolic rates to a mere fraction of their usual levels. Triggered by changes in day length and temperature, insects use this survival strategy to suspend their life cycle, waiting until conditions improve.
Imagine being able to time travel—freezing everything until the world is ready for you again. That’s essentially what insects do during diapause, stopping all activity and waiting for the right moment to resume growth and reproduction. This underlying biology's sheer “cool” factor has fascinated researchers for generations, while its ecological impact is equally significant.
This remarkable adaptation doesn’t just help insects survive—it ripples through ecosystems. By carefully timing their reawakening, these creatures shape food chains and nutrient cycles, playing a crucial role in nature’s balance.
Note: There’s still some debate among scientists about the origins of diapause—did it evolve once and get lost in certain species, or did it evolve independently many times?
The role of heat shock proteins
While diapause slows down most biological processes, some insects have extra tools in their survival arsenal—such as heat shock proteins.
Heat shock proteins (Hsps) act like molecular bodyguards—also known as molecular chaperones—within the cells of insects. Just like a bodyguard protects an important person, Hsps protect a cell's proteins and delicate parts from damage caused by extreme conditions—like freezing temperatures.
When an insect enters diapause, the cold can wreak havoc on its body. Here’s where Hsps step in—they prevent the insect’s insides from becoming damaged by the cold, preventing ice from forming in the wrong places inside the insect's body.
Note: If ice were to form there, it would act like tiny knives, cutting through cells and causing irreparable damage—and possibly death. The Hsps essentially "chaperone" the cell's proteins, ensuring they don’t misfold or break apart when the cold strikes.
For more information on this fascinating topic, check out the study, Up-regulation of heat shock proteins is essential for cold survival during insect diapause
Diapause in danger: Climate change’s hidden impact
But even these extraordinary adaptations aren't invincible. Climate change is throwing new hurdles at insects that depend on diapause.
Diapause may be one of nature’s most incredible survival mechanisms—and sound like the ultimate winter superpower—but even this remarkable adaptation is starting to feel the pressure. As global temperatures rise, insects that rely on diapause to outlast the cold face a challenge they never saw coming: autumns are getting warmer, and winters, while still cold, aren’t always getting cold enough.
Take Calliphora vicina, the common blowfly, for instance. Recent studies reveal a fascinating effect known as cross-generation plasticity, where the temperatures experienced by one generation can influence the cold tolerance of the next. When adult blowflies experience warmer autumns (around 68°F), their larvae end up less cold-hardy than those whose parents lived through cooler 59°F autumns. In other words, warmer falls produce offspring less resistant to freezing temperatures—an issue when winter bites.
This cross-generational inheritance of cold tolerance could spell trouble for ecosystems. If insects fail to properly enter diapause or lose their cold-hardiness, populations may struggle to survive harsh winters—leading to higher mortality rates. As a result, food chains and ecosystems could be thrown off balance.
The bigger issue? It’s not just about survival for these insects. Blowflies are just one of many species—literally and figuratively—feeling the heat. Monarch butterflies, silkworms, mosquitoes and the bean leaf beetle—to name a few—are part of at least 64 insect species that depend on diapause. When their timing or resilience goes awry, the delicate balance of food chains and nutrient cycles starts to unravel, with consequences rippling far beyond just one generation.
Fascinating fact: Rootworms playing the long game
Some Northern Corn Rootworm (Diabrotica barberi) populations have evolved a remarkable strategy to outsmart crop rotations by keeping their eggs dormant for up to four winters. This extended diapause allows them to emerge precisely when corn is planted, making traditional rotation strategies ineffective and presenting a challenge for farmers.
Timing is everything: Diapause across life stages
Diapause can occur at various points in an insect’s lifecycle—egg, larval, pupal or even adult —depending on which stage is most vulnerable to environmental stressors. In fact, insects have cleverly evolved to halt development at the most critical moment, ensuring maximum energy conservation and survival. This timing flexibility highlights how diapause functions as a finely tuned survival strategy, as detailed in Insect Diapause: Developmental and Behavioral Mechanisms.
Some species, like silkworms, enter diapause as eggs, not only halting development but synchronizing their life cycle with the environment. This ensures that they hatch only when mulberry leaves—their primary food source—are available in the spring, making this a vital survival strategy during long winters.
On the other hand, insects like the flesh fly (Sarcophaga crassipalpis) undergo diapause during the pupal stage. This allows them to survive the cold with the help of stress proteins and metabolic adjustments, ensuring they emerge when conditions become favorable again.
This strategic timing of diapause demonstrates just how adaptable insects are, allowing them to preserve their energy and survive periods of extreme cold or drought until conditions improve.
But while diapause offers incredible protection, some insects take survival one step further, mastering even more extreme methods to withstand the cold.
Extreme cold champions
Some insects go above and beyond diapause to survive the winter freeze.
- The European corn borer (Ostrinia nubilalis) might be small, but it’s a cold-weather champ. It survives temperatures as low as -40°F by producing a natural "antifreeze" of proteins and molecules to stop its cells from freezing. In winter, it switches to "low power mode", cutting its oxygen use and boosting an enzyme that helps it survive with minimal resources. Nestled in corn stalks, it waits for spring to kickstart its life cycle again.
- The Antarctic midge (Belgica antarctica) might be smaller than a pea, but it's the largest land animal—and the only native insect—in Antarctica. Despite its tiny size, this resilient midge has evolved incredible adaptations to survive in one of the harshest environments on Earth. For up to six months of its two-year life cycle, it remains in diapause, conserving energy during the extreme Antarctic winter. Through a combination of freeze tolerance, cryoprotective dehydration and burrowing, the midge manages to withstand temperatures that would be fatal for most other creatures.
- The arctic woolly bear moth (Gynaephora groenlandica) spends up to 90% of its life frozen, surviving extreme temperatures as low as -70°F. Producing glycerol—a natural antifreeze—it can withstand some of the longest, coldest winters on Earth. This moth has a remarkable 7-year life cycle, but it is only active for three weeks a year, spending the rest of its time in hibernation. In its final year, it transforms into an adult, mates and lays eggs—all within one week, before starting the cycle again.
These cold-weather adaptations are not just biological curiosities—they have real-world implications, especially when it comes to insects critical to our ecosystems and food supply.
Why it matters: The bumblebee plight
Just as some insects have evolved incredible cold-weather adaptations, others—like bumblebees—face new dangers as the climate shifts.
When we think about climate change, we often picture melting ice caps or extreme weather events, but the consequences reach much deeper into the natural world—right down to the survival of insects essential for our food supply. Take the bumblebee—a vital pollinator responsible for the health of many plant species and agricultural crops. Already under threat from habitat destruction and pesticides, bumblebees now face another challenge: climate-induced shifts in seasonal timing.
In particular, queen bumblebees—who enter diapause to survive winter—are becoming confused by warming temperatures. Normally, they emerge from dormancy in spring to establish a new colony. But earlier springs and warmer winters are throwing off this natural cycle. Instead of waiting until spring, some hives are producing new queens too early, causing these young bees to attempt to found colonies before enough flowers are available to support them.
The result? The offspring struggle to find food in a landscape devoid of blooms and must endure temperatures for which they are not equipped. This leads to high mortality rates, which in turn means fewer pollinators for the next growing season.
And if you believe this only affects bees, think again. Bumblebees are prolific pollinators responsible for many of the foods we love. Picture the apple pie you enjoy, the guacamole on your taco or even your morning glass of orange juice. Without these buzzing workers, crops like apples, avocados, oranges and countless other fruits and nuts would suffer, leading to reduced availability and higher prices.
So, why should you care? The fate of bumblebees and other pollinators is intimately tied to the food we eat. When diapause timing goes wrong due to climate change, it’s not just the bees that suffer—we do too.
Nature's resilient survivors
Insects may be small, but their survival strategies are nothing short of extraordinary. From entering diapause to producing natural antifreeze, these creatures have evolved remarkable ways to thrive in environments that would be fatal to most other organisms. Yet, as our world warms and seasonal patterns shift, these carefully tuned survival strategies are being disrupted—posing challenges not just for insects, but for entire ecosystems and the human food supply. The resilience of insects like the European corn borer, Antarctic midge and arctic woolly bear moth is a testament to nature's ingenuity, but it’s clear that the survival of these species, and many others, will increasingly depend on our efforts to combat climate change.
