I harvested the first cucumbers of the season this week. I’ve seen them growing for a couple weeks now, seen the flowers even longer. But haven’t seen any bees.
This caused me a bit of concern for reasons both macro and micro. The lack of bees regularly buzzing during the summer months definitely bodes ill for our food system. But on a more selfish level: I want my damn cucumbers. Without the help of pollinators, they’re not going to happen.
Cucumbers – and cucurbits in general – have male and female flowers; they require something to transfer the pollen from one to the other. Ideally, this is insects. In a pinch, it can be a human with a Q tip. Which is a real drag.
But even with the lack of bees, the cucumbers are growing. That’s because there are plenty of hover flies. Diptera syrphidae, for the bug geeks.
There are thousands of types of syrphid flies world wide, all of them striped black and yellow like bees. On my cukes alone I’ve seen three different types, distinguishable by the variation in body and wing, eyes and mouth parts.
Diptera syphidae are not like Bluebottle flies (Diptera calliphorinaea) when it comes to pollination: hover flies are intentional pollinators actively seeking out pollen and nectar to consume, and transferring it from flower to flower in the process.
But that’s not all: syrphid fly larvae are predators of common garden pests. Voracious, badass little predators, according to Cornell University: “Most syrphid fly maggots feed on aphids, thrips, leafhoppers and other soft-bodied prey like small caterpillars. They move along plant surfaces, lift their heads to grope for prey, seize and suck them dry and then discard the exoskeleton.”
I like bees; I want them around. But show me a single bee species that sucks the life out of aphids and then tosses their broken, empty shells aside like a WWF wrestler, thumping it’s chest and shouting at the crowd.
Bring the thunder, syrphidae. And the cucumbers.
Bug Guide. Syrphid Flies, retrieved from http://www.bugguide.net/node/view/196
Cranshaw, W. (2004). Garden Insects of North America.
Shelton, A. Syrphid Flies, retrieved from http://www.biocontrol.entomology.cornell.edu/predators/syrphids.php
Shepherd, M. and Black, S. H. Flower Flies, retrieved from http://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/flower_flies.shtml