Insect enthusiasts and naturalists probably find insect galls interesting or even beautiful. Gardeners and landscapers, though, may be less enthused to discover insect galls on trees and shrubs, and may be concerned about insect gall damage.
Fortunately, with few exceptions, insects galls do not damage trees and shrubs. While they may look unsightly, particularly on specimen trees, most healthy, well-established trees and shrubs will be unaffected by galls in the long run. Heavy gall formations may slow growth.
Because the negative impact of galls on plants is largely aesthetic, control measures for galls or gallmaking insects are rarely warranted. Leaf galls will fall off, either with the leaves themselves, or from the leaves once the insect or mite has emerged. Galls on twigs and branches can be pruned out. A gall that has already formed cannot be treated or sprayed to eliminate it. The gall is part of the plant itself.
Gallmaking insects, it should be noted, will attract their own biological controls in the form of parasitoids and predators. If your landscape is riddled with galls this year, give it time. Nature will restore the balance in your ecosystem.
