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Purpose of Black Flies

posted May 13, 2016, 10:45 AM by Christine Roman
May 13, 2016

Dear Parents/Guardians,

Since our playgrounds have been challenging this week with black flies, I thought I would do a little research around the purpose of these pesky insects. Here are highlights from an article written by Donna Rhodes back in May 2009 for the Salmon Press Media.

Due to the large number of black flies in our area, they are part of many birds’ and amphibians’ diets. Born from beneath running waters each spring, the hatches begin to appear as temperatures in their watery womb hit 40 to 50 degrees. When the larvae hatch, they cling to aquatic plants in the streams and actually do some good.

The larvae (the middle lifestage between eggs and the adult fly itself) are filtering creatures. While hanging onto their perches in the water, they feed on bacteria and other microorganisms in the streams and rivers. By removing these particles of vegetative and bacterial growth, they clean the water. N.H. Large Lake Fisheries Biologist Donald Miller said that the presence of black flies indicates a healthy body of water.

*Black flies are a great indicator of good water quality," he said. "They need pure, well-oxygenated water in clean-flowing streams. They filter out a lot of suspended material that is found in our streams and ultimately utilize it as food." Black flies are also a tasty tidbit for birds, swallows and warblers in particular. Bats enjoy a snack of black flies if there is not a tastier moth or beetle nearby, says UNH professor Dr. John Burger.

Have a great weekend!