Are you Swatting Gnats Again? Good!

by Emily Sigillo and Julianna King

CC Some Rights Reserved  Charley Eiseman

Take it from two soccer players who practice on grass fields: gnats are annoying! The official common name for gnats is “black flies” (Simulium jenningsi).  As larvae, black flies live in streams, so we only see the adult stage.   They are attracted to body heat, making them fly at our faces and even ending up in our mouths, an unexpected source of dietary protein for soccer players. These flies attracted so much negative attention that a group formed called Neighbors Against Gnats (NAG) in 1983. The oversupply of gnats caused the Pennsylvania government to take action against the gnats, and these programs are still in place by the Department of Environmental Protection. Yet, the decline in the gnat population was due to the increasing water pollution in the local streams. Recently, black flies have been making a comeback, and we are here to tell you why the gnats returning, and yes being irritating, is a good thing!

For quite some time, the water pollution levels were too high for the black flies to survive. In recent years, the Bureau of Clean Water in Pennsylvania has taken care to purify the streams. This impact has gone much further than just helping people in Pennsylvania, but it has also helped the gnats. Black flies are a bioindicator species. Their presence is proof that the streams are cleaner than they were decades ago!  With all this said, the state does recognize the annoyance that the gnats cause to Pennsylvanians. So, the state sprays the rivers with an insecticide called Bt, or Bacillus thuringiensis. Before you jump to any conclusions about this, Bt is a bacteria that does not have any of the negatives that chemical insecticides do. Larvae of the gnats eat this bacteria, which eliminates many gnats before they are even born, and a highly effective way of treating the water for gnats.

Black flies also play an important role in their ecosystems. While the flies are developing in the streams, they break down vegetation into an important food source for fish. Not only do they make food, but the flies are food themselves. Once they start flying, they become a  food source for birds and their baby chicks. Without them, some birds might not have enough fuel for their long journey north!

Speaking of babies, this is why gnats suck blood in the first place. Similar to mosquitoes, a female black fly needs to feed on blood for her eggs to mature. After a blood meal, the fly breaks down a protein called hemoglobin in the blood into individual amino acids, which are the building blocks of proteins. The amino acids are then used to make yolk proteins, which are the food source for the baby fly when it is inside its egg.

Now, I do realize that while their presence is a positive sign for healthy ecosystems, we don’t all want to walk around swatting and swallowing gnats every day for nine months out of the year. So, what can we do to solve this dilemma? If there are gnats in your kitchen, a simple bowl of vinegar and dish soap will attract them. On the soccer field, we do a simple trick: hold your hand above your head. Gnats tend to anti-gravitate towards the highest point of your body. So, if you’re not interested in spraying toxic chemicals all over your body to repel black flies, which may or may not be effective depending on the type you are using, this is an excellent solution for you!  

When a fly bites you, it is the saliva from the black fly that causes the itching we feel.  Although we may find gnat bites to be annoying and try these methods to avoid it, researchers have found a way for the saliva to help us! Black flies have proteins in their saliva that increase blood flow and prevent our blood from clotting. This used to get past humans’ natural defenses so the fly can obtain their meal quicker. Researchers found that these proteins could be used in humans to stop clotting and inflammatory responses associated with vascular injuries. In other words, they could be used as a treatment for heart attacks

So, next time black flies are outside annoying you, think about the positives. We may think of them as an annoyance, but many other living things couldn’t survive without them. Not only this, but the presence of black flies shows that you have clean natural water sources nearby. And who knows, maybe one day you will be able to thank them for keeping you alive too!

2 thoughts on “Are you Swatting Gnats Again? Good!”

  1. This article was super helpful for me! I never knew the trick of raising your hand above your head, or about all of the positives of the existence of gnats. Next time I’m out on a hike, I won’t be as angry at all the gnats swarming me!

  2. Leave it to Americans to create a group specifically targeting an insect! (the acronym makes a nice lil pun by the way haha) So cool that a treatment for heart attacks can come from studying the gnats. Bugs like these become helpful in the most unlikely of ways!

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