Filed under: Noticing Nature.
Blackfly season, we all are anxious for it to end. But what role does the blackfly play in the ecosystem? Is our sacrifice of a drop of blood and some minor discomfort contributing to the productivity of the blackfly’s ecosystem? In my opinion it is and I want to explain why. Blackflies spend most of their lives as wormlike larvae living in streams, the swifter the better. The larvae have mouthparts, shaped like beautiful finger-like fans, which they wave in the current to catch the tiny particles they eat. Their diet thus includes tiny bits of dead leaves, algae and bacteria from the stream. Since they prefer swift current and feed by filtering, they anchor themselves to the top of surfaces in the water so they won’t be washed downstream. This location makes them easy targets for any stream predator, including dragonfly larvae and fish. Add to that the fact that they can be abundant, with hundreds living side-by-side in a square foot of streambed. Many studies have shown that blackfly larvae make up a big chunk of the diet of trout and salmon. The larvae of these pesky flies are thus allowing plant and bacterial matter to eventually become trout and dragonfly tissue where it can then be available to terrestrial predators. So where do we fit in? Only the female blackfly needs to bite us, she requires blood proteins for complete development of her eggs. Actually there are many species of blackfly, only a few feed on humans, most feed on other warm-blooded animals. Nevertheless, the next time you scratch a blackfly bite, take comfort in the knowledge that your sacrifice contributed to the productivity of your local stream ecosystem, to the beautiful dragonflies flitting around you and perhaps to the flesh of the trout or salmon you may enjoy later on your plate.