The walnut husk fly is about the size of a housefly and very colorful. It has a yellow spot just below the areas where the wings are attached and iridescent, greenish eyes and the wings have three prominent dark bands. Blotches that are hard and dry are caused by blight disease and should not be confused with husk fly damage. This fly has one generation per year. The fly lays a cash of up to 15 eggs in the skin of the walnut often in mid to late July. These eggs hatch and start to consume the husk of the Walnut. These grubs grow in size through august where damage shows up as a blackening of the walnuts in the tree. The walnut its self is still growing until damage is wide spread. The walnut can still be used but now the husk is black and stuck to the shell making it a hassle to make an attractive edible product. In the old days the walnuts stayed green into late fall then all of a sudden they would split open spitting the treasured nut to the ground nice and clean ready to be picked up and consumed. Now that the husk fly is so wide spread we don’t see this much at all any more. The nuts stick in the tree and sometimes drop with the leaves and need a lot of cleaning before consuming. Oh well they are still nutritious and delicious! For more info click below.