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IDENTIFICATION:  There are many different kinds of galls. They are primarily caused by wasp, fly, and aphid insects and are usually more cosmetic than damaging.

HABITAT:  Many ornamental and food crops.

FEEDING HABITS:  Wasp, fly, or aphid gall insects "sting" a plant, which causes a growth that the insect uses as a home for its young. The gall serves as a shelter and food supply.

ECONOMIC IMPORTANCE:  Although unsightly, most are not considered very damaging. Tannic acid from galls has been used for centuries to tan skins of animals. Many galls contain materials that make the finest inks and dyes. Some galls contain products that have been used in medicine since the fifth century b.c.

NATURAL CONTROL:  Biodiversity.

ORGANIC CONTROL:  None needed, although healthy plants seem to have fewer galls.

INSIGHT:  Science does not yet know what makes the plants grow the curious, elaborate, and at times even beautiful structures that are absolutely foreign to the plant in the absence of the gall insect. The same species of gall insects on different species of plants causes galls that are similar while different gall insects attacking the same plant cause galls that are different. The galls also become homes for other than the initial insects.

Galls are interesting structures that form primarily in trees as swollen masses of abnormal plant tissue caused by fungi, bacteria or insects. There are many different kinds of galls primarily caused by wasps, flies, and aphid insects. Good news is that  they are usually more cosmetic than damaging. However, heavy populations of galls indicate stress in the host trees.

Tiny female gall wasps or cynipid wasps pierce twigs or leaves with her egg laying devices and deposits an eggs inside the plant tissue. Fluids deposited with the egg, and produced by the larva cause the plant cell multiplication process to begin. The larvae develops within a cavity inside the gall, feeding on material produced in the cavity lining. At maturity, the larva transforms into a pupa, and later becomes an adult that chews its way out of the gall. By causing  trees to form  galls, the gall wasp has provided food and shelter for its offspring.  Although unsightly, most galls are not considered very damaging. Natural control is biodiversity. Healthy plants to have fewer galls. Improve the general health of trees using the Basic Organic Program.

The galls below on the back side of the live oak leaves are no serious problem unless there is a heavy infestation. In that case the tree is definitely in stress for some reason. Apply the Sick Tree Treatment and the population of these galls will diminish.

Remember that the most important step of the Sick Tree Treatment is to expose the root flare of the tree.

Here are some of the interesting galls you will see in trees:

Live Oak Galls:

Red Oak Galls:



Galls on poison ivy:

Various native oak galls:

Fuzzy oak galls:


Pecan phyloxera galls:

Elm finger galls:

Gall Library Entries

Crown  |  Hackberry  |  Live Oak  |  Phylloxera
Red Oak  |  Vein Pocket  |  Wooly Oak




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