A female blue dasher dragonfly at Nature Boardwalk at Lincoln Park Zoo.
The first time I saw this dragonfly above, I was convinced I must be looking at a new species, one I’d never seen before at Nature Boardwalk at Lincoln Park Zoo. It turns out this is actually a blue dasher, one of the most common species at the pond. Although I’d counted dozens of blue dashers at Nature Boardwalk, I’d never seen a female! In this species, the females look nothing like the males (below), and apparently they’re a whole lot harder to spot.
Male blue dasher
The tendency to see many more males than females holds true for several dragonfly species at Nature Boardwalk. Blue dashers take this to an extreme, but in widow skimmers and twelve-spotted skimmers, the same pattern emerges.
Male twelve-spotted skimmer
Female twelve-spotted skimmer
So where are all the females? A number of researchers have investigated the skewed sex ratio in dragonflies and damselflies to attempt to answer this question. It’s commonly known that in most types of dragonflies and damselflies, more males are seen than females.
There isn’t a clear explanation for the disparity in sightings. One proposal is that females have less flashy coloration, are better camouflaged and are less bold than their male counterparts. According to this hypothesis, there aren’t necessarily fewer females—females are just better at going unobserved.
Another possible reason is that females may have lower survival than males, but survival rates simply aren’t known in most cases. The bottom line: we don’t yet know why we see more males than females. In any event, this makes it a special treat to see the elusive females dragonflies.