A gall is a tissue proliferation for plants. It is a plant’s reaction to tissue injury, i.e. following a bite or a sting. A gall is a kind of closed wound. They can manifest themselves as a simple growth or a complex, multi-chamber structure. For the formation of these special growths, the type of substance injected by a parasite plays an important role. Usual suspects include wasps, mosquitos, flies, lice or mites. Those who would like to learn more about galls must first learn the types of host plant. This is the only way to logically narrow down the many types of insects and substances that cause a gall to be formed. Want to see for yourself? Cut a gall and have a look inside, though you can often be confronted with only larvae. Or collect a few galls for yourself and wait patiently at home to see what hatches!