There was a big hatch of these Band-winged Meadowhawks, Sympetrum
semicinctum over the 4th of July weekend at Westwood Hills Nature Center. I
don't think I've seen this particular dragonfly before; I wonder if there is an
unusually big hatch this year, or if I've just never noticed them before (and
not just me, two other acquaintances have noted their appearance this year. Or maybe it’s some of both. Here are some relevant facts from the guide
books I consulted.
·
it is a relatively uncommon dragonfly, and
usually occurs in small numbers, unlike other meadowhawks
·
it is very susceptible to predation by fish
·
it does not compete well with other dragonfly
larva
·
it often lays eggs above the water line in vegetation,
which over-winter, and hatch the next spring when water levels rise with
melting snow and rains.
We’ve has a couple of cold, snowy winters in a row, which
has led to a very low fish population at Westwood lake. It was also a very wet spring, with higher
than normal lake levels, so maybe a higher percentage of Band-winged Meadowhawk
eggs ended up in the water this year to hatch and develop. The expanded habitat may have also led to
less competition with other dragonfly larva.
So perhaps Band-winged Meadowhawks have been present at Westwood in very
low numbers, but the combination of cold winters and a very wet spring created
very favorable conditions for this dragonfly to thrive and appear in large
numbers this year. Perhaps.
With the amber patches on all four
wings, it's a fairly distinctive dragonfly. Most species of meadowhawks are
often difficult to identify to species, though as a group they are pretty easy
to recognize. They are smaller dragonflies that often perch horizontally, with
their wings held slightly forward. Males
are generally red, and females are a yellow-orange.
You might find in some sources that this dragonfly is split into two separate species, S. semicinctum and S. occidentale, or the Western Dragonfly. The Western Dragonfly is often further split into a number of subspecies. The latest studies seem indicate that while there are geographical variations in these dragonflies, there aren’t enough differences to warrant a split into separate species.
