Next Thursday is World Bee Day. Prepare yourself for a deluge of social media and other information reminding you how dire the situation is for honey bees and why we need to save honey bees to save the world. If you can, try to redirect people toward the native bee species that really matter. If you’ve followed this blog for any length of time, you’ve heard why honey bees should not be the focus of our concern about pollinators. If you need a refresher, you can read this.
Native bees deserve a day of recognition. They deserve a lot more than that. However, it’s also worth remembering that bees are not the only group of pollinators that keep ecosystems humming along. Butterflies and moths are important. So are wasps, ants, and even beetles and hummingbirds. In some places, bats are hugely important too. But don’t forget about flies!
Flies are the most diverse group of insects in North America, with an estimated 61,000 species. Many of those species feed on pollen and/or nectar as adults. Some are specialist feeders on certain plants and others are generalists. Some flowers rely on flies for pollination, but for most, flies just provide some additional help – a little insurance in case native bees or butterflies can’t fully do the job (maybe because honey bees are suppressing their populations).
One of the reasons flies aren’t always recognized as important pollinators is that many of them are mistaken for bees. That’s understandable – many of them look a lot like bees, with similar body shapes, coloration patterns, and behaviors. One fairly dependable way to tell them apart is to look at the antennae. Most bees have fairly long antennae, but flies tend to have short little stubby antennae right between their eyes. Speaking of those eyes, fly eyes are usually noticeably larger than bee eyes too. If you’re really close, or are looking at a dead insect, you can count wings – bees have four, flies have two.
Another reason to celebrate the value of flies is that they tend to play two roles during their lives – one as larvae and a different one as adults. Bee larvae spend their childhood in the nest their mom built for them (in most cases) and feeding on the pollen and nectar their mom brought to that nest. That’s nice, but they’re not really doing much for the world at that point, are they?
Fly larvae, depending upon the species, might be eating manure or rotting meat, eating roots or other parts of plants, or hunting down other invertebrates or their eggs for food. In some cases, their mom lays an egg on a live caterpillar or other insect so the larvae, upon hatching, can burrow into that creature and eat it from the inside out. These are all important roles in ecosystems that help regulate ecological communities. Oh, and by the way, fly larvae are hugely important food sources for many other animals.
PLUS, they help out as pollinators when they grow up. That’s their side hustle.
So, on World Bee Day, and any day, really, let’s not forget about flies. Celebrate their diversity, the myriad roles they play, and even the horrific eating-creatures-alive-from-the-inside practices of a few of them. We’d sure miss them if they were gone.
The Prairie Ecologist 