An insect gall is any deformity caused by an insect. They are very common and were known by ancient man. Theophrastus, a greek, wrote about them 300 years before the birth of Christ. He wrote about their use in medicine. Some galls on animals are caused by insects, but this project is limited to galls on plants caused by insects and mites.
Insects have six legs.
Mites have eight legs and are not insects. Any abnormal growth of a plant is a gall. Some of these are caused by limbs rubbing together or cutting or biting by animals. Fungi and viruses often cause witches'-broom. Nematodes, mites, and insects are the most common causes of galls on plants.