Q: I was visiting my daughter and she pointed out that the west side of her house was covered with flies. She said it happens every year around this time. Is there a way to get rid of them?
A: I notice them each year at my home too. My theory is that these early-hatching flies are attracted to light colors or warm surfaces. If the surface happens to be a doorway, the fly comes indoors when you do.
Use a water-based outdoor insecticide to kill those on the wall. Do it early in the morning when they are too cold to move rapidly.
The best weapon against flies is to get rid of the places where they breed. If you grew up on a farm like I did, you know that flies prefer animal manure. Your daughter likely doesn’t raise chickens or cows but dog and cat droppings make excellent homes for fly eggs. Clean up around her home and yard and ask her neighbors to do the same.
If flies are indoors, sprays containing pyrethrin are generally considered safe to use if you can hit the insect directly. Don’t forget that flypaper works as well now as it did a hundred years ago. Hang a strip near a sunny window and wait for the flies to find it.