Backyard and Beyond

Dennis Paulson’s new Dragonflies and Damselflies: A Natural History‘s is a great introduction to odonating.

Paulson has written the standard field guides to American/Canadian odes as well as dozens of journal papers on odonates. The pictures in his field guides are too small; that’s these guide’ principal fault. But consider: there are 461 species to be covered in the US and Canada. There is strong sexual dimorphism in odonates, meaning at least two images for each species. Some damselfly species have four or five color forms. Dragonflies and Damselflies of the East is 519 pages long, not including glossary and index. Gotta be some hard calls for the author and publisher in this field of field guide publishing.

This new book, however, is coffee table format. It’s aimed for a popular readership. While there is a Further Resources appendix, I note the absence of a real bibliography. There’s a lot of scientific literature out there; touching base with it would have been a good thing, especially with our unparallelled ability to pull up scientific literature on the ‘net (if not full text than at least the abstract).

Chapters on natural history alternate with two-page spreads on individual species from around the world. At the time of publication, there were 6,299 described odonate species. That number is sure to change. Nearly two hundred of these were first described between 2015-2017. Only a small sample are included here, obviously, representing the great range and diversity of this order of insects.

News to me: the Common Winter Damsel (Sympecma fusca), found in southern and central Europe east to central Asia, stays dormant through the winder. They grab hold of something and sit out the winter in dormancy. The two other species in this genus are the only overwintering adult Odonates we know of. Advantage: very early start to reproduction, before predatory migratory birds show up. Disadvantage: they suffer “moderately high mortality from rodent predation” in winter. A frosted-over damselfly is still fresh meat, after all.

On the Azores, the population of Citrine Forktails (Ischnura hastata) is all female. They’re the only ode that manifests parthenogenesis. With so many species, there are many strategies and adaptations and habitats. The basic plane is the same, but the differences are what fascinates.
The Eastern Pondhawk (Erythemis simplicicollis) rates an entry because it is one of the few species in the world that seems to be increasing its numbers, going against the general decline brought about by… us. I photographed this one in Brooklyn. They thrive in any kind of fresh water; many other species have rather more specific requirements: gravel bottoms, slow moving streams, fast moving streams, muddy bottoms, etc.

What else? Much else. Up to 60% of the weight of a dragonfly is muscle used to power their four wings. “Although they operate independently, the fore- and hindwings interact with one another. The hindwings suffer slightly increased drag owing to the turbulence created in front of them by the forewings, but the positive pressure generated by the hindwings actually decreases drag on the forewings.”

There are even some numbers on flight speed: average speed of a moderate sized dragonfly: 4.5 mph. The largest dragonflies, the darners, can hit bursts of 34mph!
Sweetflag Spreadwing (Lestes forcipatus) female. Photographed in Alley Pond Park in Queens, on the same day as this
Slender Spreadwing (Lestes rectangularis). These are now the only Queens records for Lestes genus spreadwings at Odonata Central. iNaturalist has one more, seen in 2016, but nobody could get it down to species level. I have a similar problem with the third spreadwing I photographed in Ally Pond Park that day. Without the specimen in hand, identification can be impossible, but I’d rather see them flying than tucked into someone’s drawer. Brooklyn, by the way, has only one record of a spreadwing, but here too the picture is too obscure for species-level.