On a warm late summer day if you walk into a field of flowers particularly yellow flowers like goldenrods you might think you have stepped into a swarm of bees or wasps. There is intense buzzing and many small yellow and black insects on the flowers and flying all around you. But despite all appearances these are not bees or wasps at all. They are flies. Syrphid flies, also known as flower flies and hover flies, to be more exact, and there are many species that mimic bees and wasps, a good strategy if you are trying to fend off predators.
Syrphid flies are true flies in the Order Diptera (“two wings”) and Family Syrphidae. Adult syrphid flies feed on nectar, pollen, and sugary secretions from aphids. You can use their love of sweets to attract them with mixture of sugar or honey and water sprayed on surfaces like tree trunks in open areas. When moving about on flowers syrphid flies assist in the pollination of many plant species including crops we grow.
The larvae have more varied diets depending on the species. Some syrphid fly larvae feed on decaying plant matter, damp wood (perhaps for the bacteria and fungus which are more nutritious?), and subterranean parts of plants. Others prey upon aphids, scale insects, thrips, and similar sap-sucking insects and can be beneficial in crop fields and gardens. Some species lurk in ant nests where they disguise themselves with chemical secretions and eat ant larvae.
Syrphid larvae in the tribes Eristalini and Sericomyiin live in muddy stagnant water, even cesspools, where they feed on detritus. A long breathing tube from the anal segment pokes above the water to access the air. This long breathing tube has earned them the name “rat-tailed maggots”.
I recently bought “Field Guide to the Flower Flies of Eastern North America” and have found it very helpful in figuring out species of syrphids that live in my area. The book is well illustrated and includes descriptions and range maps. In the descriptions, the authors have included flowers that species typically visit if known. I have been able with this book to identify three syrphids (Eupeodes americanus, Sericomyia chrysotoxooides, Toxomerus marginatus) that had been in my “unknown” files for several years. And I’ve identified three others I photographed last week (Eristalis dimidiata, Eristalis transversa, Sphaerophoria philanthus).
Below is a small gallery of some of the syrphid flies I’ve seen here over the years.
Field Guide to the Flower Flies of Eastern North America. Jeffrey H. Skevington and Michelle M. Locke. Copyright 2019 Princeton University Press.
This small butterfly with dark brown wings and yellow spots is the Arctic Skipper (Carterocephalus palaemon). I saw it a few days ago on a warm, sunny, and humid afternoon on June 12. It was resting on a blade of grass in a sunny opening in an encroaching forest. Although the Arctic Skipper is widely distributed and ranked a G5 or “globally secure” there is only one record that I could find of it from Carlton County and it is historical but there was no information about when or where it was seen or who saw it.
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Papilionoidea (Butterflies and Skippers)
Family Hesperiidae (Skippers)
Subfamily Heteropterinae (Intermediate Skippers)
Genus/species Carterocephalus palaemon
The upper wing surface is dark brown to almost black with roughly rectangular yellow spots. Below they are like the color of a deer fawn and marked with black-rimmed yellow spots. Wingspread is 2.5 to 3.2 cm.
A circumboreal species found in North America from Alaska to Canada’s Atlantic coast and south to California and Pennsylvania. Not truly an Arctic species.
Larval Host Plants
Larvae of Carterocephalus palaemon eat grasses. In California purple reedgrass (Calamagrostis purpurascens) is reported as a larval host. In some European countries, brome (Bromus spp.) are preferred larval hosts. Purple moor-grass (Molinia caerulea) has been reported as a larval host in Scotland. Purple reedgrass is rare in Minnesota and purple moor-grass does not grow here. There are bromes both native and introduced in the state as well as the native Canada bluejoint grass (Calamagrostis canadensis). It is likely that Carterocephalus palaemon larvae feed on other grass species besides the few mentioned in the literature.
Another busy and late night but a productive one. I added several more species to the checklist but this one was already on the list after I found a caterpillar of the species last fall. It is the Laurel Sphinx Moth (Sphinx kalmiae). There is an abundance of potential food plants (ash and lilac) for this moth to choose from right around my house so I am hoping to find a few caterpillars later this summer.
Its been a busy month and a half of mothing so far with many new species and as well as returning species seen last summer. As of May 31 the moth checklist for 2018 is now at 57 species with a combined checklist for 2017 and 2018 of 225 species. There are also many new ones in the “Unknown Moths” file. The latest checklist additions, all observed between May 26 and May 31, are Argyrotaenia mariana, Helcystogramma melanocarpa, Acronicta morula, Elaphria versicolor, Eucosma awemeana, Petrophora subaequaria, Acronicta interrupta, Ancylis albacostana, Leuconycta diphteroides, Ectropis crepuscularia, Orthofidonia flavivenata, Palpita magniferalis, Bibarrambla allenella, Plagodis pulveraria, Monopis monachella, Pero morrisonaria, Apotomis funerea, Semioscopis packardella, Tacparia desertata, Hydriomena renunciata, and Galgula partita. Returning species include Caloptilia stigmatella, Pseudeustrotia carneola, Euphyia intermediata, Tetracis crocallata, Gluphisia septentrionalis, Prochoerodes lineola, Metanema determinata, Metanema inatomaria, Plutella xylostella, Clostera albosigma, Acronicta lobeliae, and Idia americalis.