Natural Causes

Greg, thanks for mentioning cars. I overlooked that. A large cause of mortality for meadowhawk eggs is habitat alteration. Each year adults mistake mowed lawns and trails as dried temporary ponds, the short grass to tall grass transition at lawn edge and trail edge resembling a small dried pond. All the eggs mistakenly deposited in these areas have no chance of survival.

I have never seen one die naturally as Ken's account, but I have found some very mature-looking specimens that I believe likely just ran out of time. Occasionally I'll find corpses of obviously mature dragonflies with various decomposers doing their thing, but it's possible a bird or asilid ended the dragonfly's life and dropped them.

Often I think about what both of you mentioned, essentially "false positives" in habitat selection as a result of urban ecology. Even examples such as possible increased predator success rate due heightened visibility of Libellula croceipennis seen on a car antenna. Each year I watch Epitheca petechialis and some other species patrol and occasionally oviposit in residential swimming pools.

I'm sure we could each think of other examples and plenty of examples outside the realm of dragonflies. Anyway, it's interesting to think about. Modern urban/suburban environments have been around such a short time in relation to insect selection and evolution (and will possibly just be a blip on the radar) but they essentially throw a wrench in eons of practical selection.

Anomalous situations have altered and wiped out lineages in the past so in a sense the false positives in humanized environments isn't really new. One species thrives (or destroys habitats, builds needlessly large houses, contaminates water sources, etc.) at the expense of others. I guess the difference is these are conscious modifications rather than instinctual.