Winter treatments for black fly larvae begin!

Black fly survive winter primarily in their larval stage. Although water temperatures are not optimal for growth, black fly larvae are still feeding and developing. On a warm sunny winter day (which we occasionally see in Idaho) black flies will hatch out and lay their eggs into a water system. Black flies have a unique adaptive attribute where females can reproduce autogenously (without mating). Being able to hatch out on a warm winter day and autogenously lay up to 600 eggs allows their species to rapidly colonize early in spring.

Applications of VectoBac 12AS are done based on water flows. In early spring and during certain weeks in the summer, river flows can be well over 7,000 cubic feet of water per second (cfs). But during the winter, flows typically average between 400 - 700 cfs and so the cost of treating is about a tenth of the cost at high flows. By eliminating larva in the winter, it takes black flies longer to migrate to our area from other parts of the state and become established.

A key part of our spring and summer black fly control is actually done from November through February. By effectively controlling black fly larva through the winter, we can save a lot of time and money in the spring and summer.