How many types of galls are there?
In fact, there are more than 2,000 species of gall-making insects in the United States. The association between the gall-making organism and the host plant is usually quite specific. Different organisms produce galls of characteristic size, shape and color.
What insects form galls?
Galls are formed mainly by gall midges and some other flies (Diptera), gall wasps (Hymenoptera), and mites (Acarina), but are also caused by aphids (Homoptera), sawflies (Hymenoptera), and a few moths (Lepidoptera) and beetles (Coleoptera).
Why do insects make galls?
Some galls act as “physiologic sinks”, concentrating resources in the gall from the surrounding plant parts. Galls may also provide the insect with physical protection from predators. Insect galls are usually induced by chemicals injected by the larvae of the insects into the plants, and possibly mechanical damage.
What do galls look like?
The appearance is generally recognized as a bump, peak, or scabby area of plant flesh. They are firm to the touch and may be thickly coating a plant, found singly or in pairs. Leaf galls on plants might be green and match the plant material. They might also be bright pink or red and resemble large pimples.
What are stem galls?
Stem gall is caused by a fungus that is most damaging to injured or stressed plants. Stem gall causes galls or swellings to form on twigs or stems of forsythia, often high on the plant. Twigs or stems may die back.
What is an oak gall wasp?
Gall wasps are small, brown wasps with the abdomen flattened side to side. Many gall wasps develop for 2 or 3 years in woody galls on the twigs of oaks. Adults then emerge from the twig galls during the winter. They lay eggs in the buds and die.
What are tree galls?
Galls are abnormal growths that occur on leaves, twigs, roots, or flowers of many plants. Most galls are caused by irritation and/or stimulation of plant cells due to feeding or egg-laying by insects such as aphids, midges, wasps, or mites. Each type of gall-producer is specific to a particular kind of plant.
Is gall poisonous?
Let’s consider some plants that fit the characteristics of gall. Obviously, it must be both bitter and toxic. It should also be possible to make it into a decoction (water solution of the plant). One plant stands out in its toxicity, however–hemlock.
Are galls harmful?
Are galls harmful to trees? Galls can have an ugly appearance. However, most do not seriously affect the health of a plant or tree. Heavy infestations may distort leaves or cause an early leaf drop.
Are burls galls?
Tumor growth in plants is commonly known as gall or burl. Galls contain knots, callus, ingrown bark and stains, whereas, burls are bark-covered and display wildly contorted grain. These tumors can occur on twigs, branches, trunks, roots, or leaves (like seen above) and might be numerous per host.
