Why do common house flies fly in square formation, hard on the angles?

Question

Some flies swoop and circle like the birds and bees but the black flies around my home and barn fly in abrupt 90degree turns. Is there an anatomical reason for this?

Answer 1

flies (Diptera) have only two wings, and two undeveloped wings called "halteres" sort of club shaped things, they rotate like a gyroscope sort of

THAT is why flies can hover and dart like that, while bees and other insects can't

Answer 2

I don't know about the "square formation", but most insects are capable of flying in the fashion you described it. It is simply because the fly flies fast (say THAT ten times fast!) that it appears to be "abrupt". Most insects, as well as mammals and fish, will take a second or two to examine their surroundings, which you can see by them hovering, seemingly for no reason. In fact, insects do not see as we do. A fly's compound eyes allows them to see the world as a series of lights and shadows. As soon as something changes that, such as a human creeping closer to swat them from the wall or buzzing by one's face, it reacts by flying in the opposite direction. So, there is no "anatomical" reason, per se; it is a survival reflex.