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September 21, 2011

Galls

Have you ever been on a walk in the woods, a park or through a field of weeds and wildflowers and noticed strange bumps on tree twigs and leaves or plant stems? These are called galls, abnormal growths triggered by an injury or irritation to the plant, often caused by a living organism like an insect. Galls provide food and shelter for developing larvae.

When some insects or mites feed on certain plants or lay eggs on plant tissue, galls begin to form. There are more than 1,500 species of gall producers; plant mites, aphids and plant lice, gall midges and gall wasps are a few. Each kind of gall producer causes its own type of gall to form. No one is really sure what makes galls form, but it may be that insects or mites inject or secrete a chemical substance onto a plant when laying eggs in or on it.

galls on leaves

Galls can be as simple as bumps on a leaf or complicated structures that are as hard as rock. While there are many gall producers, only a few plants grow galls, including willows, oaks, goldenrod and asters. If gall producers don't choose the correct species of plant, a gall will not form.

Insect or mite eggs hatch inside a gall in spring or early summer, safe from predators and harsh weather. In the fall, the larva makes an exit tunnel to use the next spring when it enters the world as an adult. After the insect or mite leaves, the gall remains on the plant, often providing shelter or food for other insects like beetles or caterpillars.

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Family Fun

Going on a Gall Hunt

Galls come in many shapes, sizes and textures. Some galls are fluffy, while others are scaly and bumpy. Most often, they grow on oak trees but can be found on other plants like aster flower stems, blackberries and goldenrods. You can find galls on nearly all the parts of oak trees-leaves, buds, branches and roots. For other plants, look on the leaves, stems and ends of twigs.

What's Inside?

a gall cut in half

Those strange lumps, bumps and balls are actually habitats for some insects and mites. After you have found a gall (preferably a goldenrod ball gall), inspect the outside carefully. Is there an exit hole? Is it soft like a pom-pom or hard like a rock? With the help of an adult, cut the gall in half. Look inside for an insect, an exit route and how much of the inside of the gall has been eaten.

Read Conservationist for Kids for more information and activities!

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Upcoming DEC Events

Hudson Valley

Stony Kill Farm Environmental Education Center

(currently closed due to fiscal constraints, but the Stony Kill Foundation is sponsoring events)

A Fall Day on the Farm
Saturday, October 1 from 11:00 AM to 3:00 PM

Norrie Point Environmental Center

Discover Norrie Ramble
Saturday, September 24 from 2:00 PM to 4:00 PM
Join us on a family-friendly 2.5 mile hike along the scenic banks of the Hudson River.

Capital Region

Five Rivers Environmental Education Center

History Happened Here: CCC Camp S-72
Saturday, September 24 at 2:00 PM

Family Fun: Squirrels and Their Kin
Saturday, October 1 at 10:00 AM
Parents and children must accompany each other. Call 518-475-0291 to register by Wednesday, September October 28.

Watchable Wildlife: Reptiles and Amphibians
Saturday, October 1 at 2:00 PM

Event Descriptions at Five Rivers

Albany Pine Bush Preserve Discovery Center

Brilliant and Bristly Buckmoths
Saturday, September 24 from 11:00 AM to 12:00 PM
Call 518-456-0655 to register. Cost: $2.00/person, $5.00/family, children under 5 free.

More events at Albany Pine Bush Discovery Center

Western New York

Reinstein Woods Environmental Education Center

Advance registration is required. Call 716-683-5959.

After-School Escape
Thursday, September 22 and 29 at 4:30 PM
For children in grades K-5. No registration required.

Mushrooms and Fungi: A Monarchy of Their Own
Saturday, September 24 at 10:00 AM
For adults and children age 8 and older.

Fall Bird Walk
Sunday, September 25 at 9:00 AM

Habitat Hunt
Sunday, September 25 at 2:00 PM
For children under age 12.

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Alien Investigation Hike
Thursday, September 29 at 7:00 PM

Busy Beavers
Wednesday, October 5 at 6:30 PM

Event Descriptions at Reinstein

Events at other Nature Centers throughout the State