What is life like for an insect on these dry winter days?
Although our winter has been mild here, in Northern Pennsylvania, we had what is referred to as a January thaw on the 10th thru the 13th.
During this January thaw, we had a wasp flying inside our home on the first day of the thaw; on the 13th, a fly was buzzing around the parishioners in church, and later that day, I killed a stink bug in our home.
Insects are different than animals in that they can’t generate their own heat internally.
Instead, insects need to either find an external source of heat or adapt themselves to live without heat.
Some insects have the capability of freezing and still survive, while other insects must avoid freezing.
Insects survive winter in different ways. One way is to migrate.
The Monarch butterflies, which are the foremost example of our migrating insects, migrate to warmer climates and then clump together in protected spaces.
Many insects successfully pass the winter as immature larvae.
For example, the woolly bear caterpillar uses the protection of a heavy cover of leaf litter or a similar shelter, while other insects replace the water in their bodies with glycerol, a type of antifreeze.
Some grubs, such as the Japanese beetle, simply burrow deep in the soil below the frost line to escape the cold.
The eastern tent caterpillar overwinters as an egg, within an egg mass of 150 to 400 eggs.
These masses, which are covered with a shiny, black varnish-like material, encircle tree branches the size of a pencil or smaller in diameter.
After hatching in early March, the caterpillars from one egg mass stay together and spin a silken tent in a crotch of a tree.
They emerge to feed on leaves either in early morning, evening or at night when it is not too cold.
In the spring, the newly hatched larvae do not travel for food because the eggs were laid on a tree of their preferred food.
Many adult insects die off, leaving their offspring to carry on their genetic legacy. Throughout the winter, numerous insects remain active under the ice of rivers and ponds.
Aquatic insects, such as dragonflies, stoneflies, mayflies and damselflies, live as nymphs under water and also beneath the ice, where they feed actively and grow during the winter.
In the spring, the nymphs emerge as adults.
The praying mantis is a good example of insects that lay eggs encased in a hard case.
The Lady Bird beetles, which hibernate, are seen in great numbers in the fall as they congregate together to find shelter, often in our homes.
Many large wasps seek winter shelter in the eaves and attics of houses or barns, while tree holes, leaf litter, under logs and rocks are common shelters for overwintering adult insects.
One of the first butterflies seen in the spring is the mourning cloak butterfly.
This butterfly, which reduces the water content in its body and builds up glycerol that acts as antifreeze, hibernates in tree holes or other shelters.
Perhaps the honey bee has the most fascinating way to keep warm.
Up until recently, it was thought by many scientists that the honey bee hives were kept warm by the bees congregating together; however, a new honey bee job has been discovered, that of a heater bee.
Usually, bees are assigned a special job in the hive, by their age.
It is now known that a bee of any age can become a heater bee.
The heater bee accomplishes his duties by either rapidly vibrating its abdomen, which causes heat.
The heater bee has been known to remove its wings, which allows vigorous use of the wing muscles, without actually moving the wings, This allows for a higher than normal body temperature.
Along with this discovery, it was also found why queen bees leave certain cells empty. Previously, this was thought of as an undesirable quality of a queen; therefore, queens that left empty cells were sought out and removed.
In fact, these empty cells were found to be essential to a healthy hive.
Before the discovery of heater bees using infrared technology, it was thought the bees that crawled in these empty cells were cleaning them out, when actually the heater bees where crawling inside these cells to keep the surrounding cells at the proper temperature.
A maximum of 70 or more cells were warmed per heater bee.
A heater bee can also directly regulate the temperature in individual cells by standing over the cell and pressing its thorax against a cell. Previously bee keepers had believed the bees were only resting when in reality the bees were working their wing muscles extremely hard to heat up the cells with their higher body heat.
Besides performing the task of heating the brood cells, heater bees also help regulate the overall temperature of the hive.
If a bee’s body temperature drops below approximately 95 degrees, the ability to fly is lost. If the temperature drops low enough, they lose the ability to move.
As the temperature drops the bees clump together towards the middle of the hive, surrounding the queen.
While the temperature on the inside of the cluster stays warm, the bees on the outer parts of the cluster are much cooler.
The swarm occasionally rotates with the outer bees moving to the inside of the cluster, giving all of the bees a chance to keep warm enough to survive.
Despite their strenuous efforts, bee colonies can potentially die off or lose most of their members to the cold of winter.