The maggots feed for 14 to 30 days. It is built from the insect ' s skin, and named for its resemblance to a seed from the flax plant. Adults then emerge and start a new generation. If it is too hot or cold, Hessian flies remain as maggots inside the flaxseed until the weather moderates. There are 4 to 6 generations per year of this pest in the South.
Generations tend to overlap.
The pest oversummers as flaxseeds in wheat stubble. The first generation in September is generally on volunteer wheat or on wild grass hosts, the most important of which is little barley. Then there are often two more generations in the fall and early winter. There is usually one spring generation in northern Alabama, and there may be two spring generations in southern Alabama.