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Little bugs provide a big meal for grasses

April 19, 2017 GMT

Midge flies that look like mosquitoes but don’t bite are called chironomids. Although harmless, they can hatch in such enormous swarms — like a huge cloud of bugs — that they will freak you out.

At a lake in northern Iceland — named Myvatn or “midge lake” — so many of the bugs can hatch in the spring and summer that they darken the sky and make it difficult to breathe. That’s partly because a single midge can lay up to 3,000 eggs. During a good season, that can mean billions of midges hatch out.

That’s because during the summer, the midge’s life cycle can go from egg to larva to pupa and finally an adult fly that hatches from the water as quickly as two to three weeks. Over the cold months of winter the larvae wait until the water gets warm again in the spring before they grow up and hatch out.

Some scientists got the idea to try and figure out what effect all of those bugs have on the plants surrounding midge lake. They set up an experiment and found that when there were lots of midges, the grass around the lake grew really well — fertilized by the dead midges that fall to the ground. Shepherds in the area even call the grass midge grass.

Claudio Gratton, a University of Wisconsin–Madison professor, figured out that the midges were equal in nutrition to feeding the grasses around the lake a half-million Big Macs — if the grass ate Big Macs, which they don’t. But it’s a cool way to point out that there’s a lot of food value in all of those bugs.

In addition to fertilizing the soil in areas where there may not be a lot of food for plants, places like Iceland where it’s cold most of the year, midges are an important food source for many fish even in places like Montana and Wyoming. Fly anglers have several types of flies that imitate the different life stages of midges to catch fish when these bugs are filling the water.

The research points out that even little things, like bugs, can have a big effect on other things, like plants.

— Brett French, Gazette Outdoors editor