Monday, January 21, 2019

Where the bugs are

By Beth Sullivan
It’s really beginning to feel like winter. The temperatures have really taken the downward turn, and as I write this, we are anticipating a winter storm. We have had a few random warmer days when I have noticed small flies doing an air dance outside the window in the sun and the winter moths were out on warmer nights several weeks ago, but overall, the insects are not in evidence at this time of year. There are, however, birds that rely on insect protein to be part of their winter diet.

Spring or bust

Insect species have different ways of surviving the winter. In many cases, though, it is not in the adult form. With the exception of those that migrate, like some large dragonflies, or hibernate in their adult form like some bees and hornets, most are in some other stage of their life cycle. Many insects lay their eggs in the fall before they die. The eggs winter-over and hatch in the spring if they are not disturbed or eaten by birds. Most insect eggs are protected in ways to deter birds: think of praying mantis egg masses which are straw like and uninviting. Rarely have I seen a bird attack a mantis egg case. Other insects, most notably species of flies or small wasps, lay their eggs inside plant tissue which then modifies itself to create a protective casing around the egg and later, the developing larva. These are galls. The type most visible now is the goldenrod gall. The stem of the goldenrod forms a ball of tissue around the egg which stays intact all winter. They can be seen easily at field edges. They are not, however fully protected from the eyes and beaks of small birds. The downy woodpeckers and black-capped chickadees are noted for alighting on the sturdy stem and pecking into the gall to expose the egg, and then picking it out . Perfect protein.
Paper wasps, or white faced hornets, make the big gray nests that hang unnoticed overhead all summer and are only revealed when the leaves fall. Very often the colony is killed by the cold before all the eggs have hatched or larvae developed in the fall. I have watched several species of birds, including blue jays and titmice, go after such nests as they remain hanging or even rip at them once they fall. The frozen eggs and larvae are great sustenance.
The paper nest of the hornet may still contain unhatched larvae and eggs well into the winter.

Some flies and wasps will inject an egg into the goldenrod stem which swells around it, creating a gall.

Inside the gall, the egg and then the developing larvae are protected over winter.

Winter treehouse

Other groups of insects spend the winter under bark flaps and in crevices on trees. They can be adults, eggs, larvae, or pupae. Some are even embedded in bundles of lichen or deeper in holes where there may be some rot. This is also where the birds know where to look. Spend some winter day observing a tree, preferably from inside at a warm window. These persistent birds, woodpeckers, chickadees, titmice, and kinglets, among others, will hop along branches, inspecting all surfaces. What is also interesting is observing how each species of bird approaches the task. The nuthatches will always work a tree going head first, down. They inspect bark flaps and cracks from this particular angle. Another very special, very small, bird is the brown creeper. They are not nearly as common as the other birds, and their camouflage is so good they are rarely spotted, except as they move around a tree trunk. This birds start at the bottom of the tree and work their way up the tree, examining the underside of everything and finding what the nuthatches may have left behind. They each have their own niche.
Of course the larger woodpeckers have the greatest advantage of having a big enough beak to delve deep into the heart of a tree, especially dead or rotting ones, to find the ants and termites and beetles in all stages.
The insects are out there. You just need to have a bird-brain to find them.
The tiny brown creeper goes headfirst up a tree then drops down to the bottom to do it again.

The white breasted nuthatch will go down the tree headfirst.

Woodpeckers with long, strong beaks can probe deep inside a tree looking for insects. 

Photographs by Beth Sullivan.

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