Cordulegastridae! And, field season - that's a wrap!
The last Maine teachers of the year have sampled! Hannah & I were out with two teachers (3 environmental science classes) from Scarborough High School over the past two days. We visited three sites: one is Mill Brook, where we've sampled each year before; one was a new site, an urban stream in Portland; and the third was another new site, a nice stream in a mostly forested spot with some pasture in Scarborough.
The urban stream had very slim pickings for dragonfly larvae (though we got a couple). Overwhelmingly, we found scuds, a more pollution tolerant invertebrate we would expect at such a site.
The two other streams, though, had good numbers of dragonfly larvae. One family we found most abundantly at both sites was the Cordulegastridae. We don't always find these elsewhere, but have found them at Mill Brook now at least two years in a row. So, I hunted down a bit more info about them, which you can read here: http://insects.ummz.lsa.umich.edu/michodo/mol/Corduleg.htm
My take-aways from this description is that there are few species - probably only a max of about 5 species in the East, and one is rare; the most common species is C. maculata; and they are, like Gomphids, a sit-and-wait predator that burrows into sand/silt. So, I think these will be a really fascinating family to learn more about.
Thanks to everyone for their hard work this field season!