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.
Early Sunday morning I saw a group of bronze-headed shield bugs (Homaemus aeneifrons) sunning themselves on the seed heads of Canadian hawkweed (Hieracium umbellatum). The previous night had been very cool with temperatures dipping to 40 degrees F and this cluster of seed heads facing due east into the sun was a perfect place to warm up. In all, there were six bugs catching the early morning sun.
Homaemus aeneifron is widespread in North America occurring as far south as Kansas and Arizona and as far west as Alaska, British Columbia, and California. It is frequently found in moist meadows and weedy areas. Some reports state that it feeds on grasses and sedges (Carex) and rushes (Juncus) but one has it feeding on Monarda fistulosa (wild bergamot) and Oenothera biennis (evening primrose). These on hawkweed did not appear to be feeding. Beyond catching some rays it was hard to say why they were all there.
My mothing nights find more than moths. Beetles, bugs, flies, wasps, spiders, and crickets, even snakes and frogs, are frequent visitors to the porch light. The latest non-lepidopteran to make an appearance is the sword-bearing conehead (Neoconocephalus ensiger). It is a new addition to my insect checklist and is one of five species of Tettigoniidae (Katydids) that I’ve identified from here.
The sword-bearing conehead is a large insect with males growing 4.5 to 5.5 cm, and females 5.2 to 6.4 cm. The head is conical with the sides pinched-in and black below. The body’s lower surface is edged in black. The stridulatory vein, which is used to make the call song in males, is long and weakly swollen. The ovipositor is blade-like and nearly the length of the body hence the name “sword-bearing”. Two color forms, green and brown, exist.
Sword-bearing conehead is common across much of the eastern and north-central US and ranges as far north as Manitoba, Ontario, Quebec, and New Brunswick in Canada. Habitat includes damp grassy areas, roadsides, and weedy areas where they feed on grasses and sedges including the flowers and developing seeds.
…during much of July and so will be posting a little less frequently. But summer has arrived and brings with it a new group of moths that love the hot and humid weather. Here are five of the seventeen new moths plus one returning visitor that showed up at my porch light over the weekend. I’ll be writing about these species later in August. There are already a few in the works on the moths Habrosyne scripta (almost done!), Oreta rosea, Phlogophora iris, Campaea perlata, and Monopis spilotella seen this year and last year.
Xanthotype sp, one of three species found here and nearly impossible to tell apart from a photo alone.