Did you wonder what those yellow ropes floating in the canals were?
Yellow ropes are one of the ways that the Twin Falls County Pest Abatement District (TFCPAD) sampled for Black Fly Larvae and gauged the effectiveness of the treatments. Buffalo gnats or Black Flies can only develop in moving water. Larvae anchor themselves to rocks or vegetation and let the flowing water bring them food. Depending on water temperature and food, they can develop into adults in as little as a week or they can take up to several months. Adults can travel up to 30 miles. Controlling Black Flies is best accomplished in the larval stage on a regional scale, not just in one county! When larvae are at the right stage of development TFCPAD uses a natural bacterial product called Bti(Bacillus thuringiensis v. israelnsis)applied to the water.Larvae see this as food and consume it. They have an alkaline gut which reacts with Bti causing lesions which quickly kills them. Bti has little impact on non targets and is very safe to use. It is also effective against mosquito larvae.
You can help reduce Black Fly numbers by reducing habitat! Keeping ditches and streams clean and free of debris, and vegetation mowed will help. As you can see in the photo, this little blade of grass hanging in the canal was providing good habitat for Black Fly larvae
TFCPAD samples for Black Fly Larvae in all waterways in the county and treats with Bti when appropriate.