In warmer months, it’s almost impossible to ignore the insects and insect-like creatures that surround us. Brilliant spider webs glisten with a morning dew, ants march along patios and sidewalks to their hills in the grass, and mosquitoes buzz near our ears as we slap at them and scratch the welts they leave on exposed skin.
As temperatures drop, these critters just as easily fade from sight and our thoughts. But they’re still out there, in some form or another, waiting out the frigid months before re-emerging. How they do it, however, depends on the type of insect.
“A key fact to remember is that insects and spiders, unlike people, do not maintain constant internal temperatures,” said Gwen Pearson, outreach coordinator in Purdue’s Department of Entomology. “They are at the mercy of the elements in terms of their temperature, especially in winter, and they have many ways of surviving until it’s warm enough for them to thrive.”
Those strategies include migrating to warmer locales or sneaking into houses, tree bark, the ground, or deep water, or utilizing compounds in their blood as “antifreeze” to keep from becoming ice cubes.
Here are some of the interesting stories Pearson has about how insects survive the winter.
Moths and butterflies
One of the most famous overwintering strategies for butterflies is the monarch migration each fall. These butterflies seek out the warmer climes of Mexico — with some traveling as many as 3,000 miles one direction — before returning to the United States in the spring.
Black cutworms, a scourge for soybeans, gardens and golf courses, also migrate as mature moths. These pests can travel the distance from Texas to Minnesota in just two days in the spring.
More commonly, moths and butterflies in Indiana tough out the cold in different life stages.
Luna moths survive in the pupa form. They build their cocoons in the shelter of leaf litter and emerge in the spring. Imperial moths burrow into the ground as caterpillars and spend the winter as pupae, resurfacing in the spring. Mourning cloak butterflies have an internal compound that acts as an antifreeze, allowing them to survive winters in their adult forms while tucked under rocks or in tree bark crevices.
Fun fact: Wooly bear caterpillars, which will eventually become Isabell tiger moths, find nooks and crannies to tuck away in to spend the winter. They can freeze and thaw several times without suffering any harm.
Springtails
Never heard of a springtail? Most people call these little arthropods “snow fleas.” They’re one of the few insect-like creatures people tend to notice as active outdoors during the winter months. They get their name because, like fleas, they’re tiny, are great jumpers and have black bodies that stand out against the white snow. They are no relation to actual fleas, however, and they are harmless.
Despite their association with snow, springtails are active year-round and their presence in your garden is a sign that you have good soil. They can live in snow banks during the cold months and some species produce ethylene glycol, the same compound that is used as antifreeze in vehicle radiators.
Fun fact: Scientists can manufacture a protein springtails use to keep from freezing. They hope to use it for human tissue, extending the time harvested organs can remain viable for transplantation.
Ants
Ants don’t hibernate, per se, but pretty close to it. Many ants bulk up, eating as much as they can in the fall and burrowing into the ground to wait out the winter in their colonies. They huddle together to keep warm, living off body fat until the spring.
Fun fact: When ants find food, they leave odor trails as they head back to their colonies, giving friends and family a way to find their next meals.
Bees
We all know that the queen bee rules the roost. Bumble bee queens actually rule it alone for many months each year.
In the late summer or early fall, bumble bee queens lay eggs that won’t become worker bees. These new bees’ only job is to procreate and produce the generation that will live through the next year. By the time winter has arrived, all worker bees, males and former queens, die off. That leaves just new females, who will become a new generation of queens in the spring.
These queens (they have already mated in the fall) feed on pollen to build up fat reserves to live in loose soil and plant debris for the winter, producing their own antifreeze-like compound to survive harsh winters. Then they chill, literally, for about six months until temperatures warm, and then they lay worker eggs and start the life cycle again.
Fun fact: The fuzz on bumblebees keeps them warm, helping them survive the cold in early weeks of spring. They also shake quickly, much like humans shiver, to warm up their flight muscles in the cold.
Aquatic insects
In warmer months, mosquitoes, dragonflies, mayflies and other insects buzz around us, so it can be difficult to think of them as aquatic organisms. But that’s exactly what they are, especially in winter.
After the cold sets in, the immature, wingless versions of these insects (eggs, nymphs, larva) settle into ponds and lakes. Water maintains a fairly stable temperature as you drop down the water column, and these insects find a place to wait out the winter. Many species can tolerate super cold conditions and will not freeze until well below 0 degrees Fahrenheit.
Fun fact: Dragonflies can live underwater in the nymphal stage for years and are ferocious predators. They extend mouth parts out to capture and hold prey while they eat them.
Ticks
After spending time out in nature during the warmer months, many people know it’s a good idea to do a once-over of your body to check for ticks. These parasitic arachnids burrow their heads into a victim and suck out a blood meal.Many also carry pathogens that can pass on Lyme disease, anaplasmosis, Rocky Mountain spotted fever and a host of other illnesses.
As temperatures drop, many species of ticks go dormant and rest in leaf litter and other debris. When this happens, many who are vigilant during warm months erroneously believe that their risk of picking up a tick vanishes. But ticks can become active again at any time if the temperature rises above freezing, making it a good idea to check for ticks any time you’ve been outdoors where ticks may be active.
Fun fact: Not all ticks become active when temperatures rise in the winter. Female blacklegged ticks must have a blood meal before spring in order to lay eggs. These ticks will “wake up” from their dormant state on warm winter days to look for a quick bite.
Homebodies
While you may not encounter too many insects or arachnids outdoors in winter, there are many you may find that sneak into homes to ride out the cold months.
Spiders like garages and attics where they can produce sacs that are unlikely to be disturbed by people. These sacs may hold eggs or hatched baby spiders that will emerge in the spring. Some spiders that don’t seek indoor shelter produce antifreeze and tuck away in leaf litter or other protected nooks.
Cluster flies, some ladybugs and stink bugs are attracted to warm, sunny sports on the sides of houses in the late fall. They tend to find cracks that allow them inside homes as temperatures drop. Finding and sealing up these vulnerable spots would not only keep the bugs out but save you at least a few dollars on heating and cooling bills.
Even indoors, many of these insects enter diapause, a period of suspended development like hibernation. They’re either inside or tucked away somewhere outside, waiting for warmer days to re-emerge and continue their lives.
Fun fact: Cluster flies lay eggs in the soil, and their maggots burrow down to feed on earthworms. They eat the worms’ insides, leaving just a shell of the worm in the soil.
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