When you see the amber of goldenrod flowers along the edges of roadsides and in open fields, you know summer is on the wane. Goldenrod nectar is a favorite of bees, butterflies, wasps, and other insects. This creates a small microcosm of interesting characters to observe on a warm, late summer day.

If you suffer from hay fever or seasonal pollen allergies and assume this beautiful yellow flower is the cause of your affliction, think again. The culprit is more likely the common ragweed which typically blooms at the same time and sometimes grows in similar open-field areas. Ragweed, although classified in the same family of plants (Asters) as the goldenrod, has a small, green, non-showy flower with pollen that blows in the wind. Goldenrods have much showier flowers in order to attract insects which do the work of pollinating as they travel from flower to flower. Ragweed, on the other hand, relies on the wind and chance, as its much lighter-weight pollen goes windborne, floating through the air to reach other ragweed plants.

You will sometimes find a goldenrod plant with either a ball- or a spindle-shaped swollen area called a “gall,” perhaps an inch or two in diameter, on its main stem. The ball is caused by the goldenrod gall fly while the spindle-shaped gall is caused by a moth. Both have similar life cycles centered on the goldenrod plant.

The small, brown goldenrod gall fly is about five millimeters long and surprisingly does not fly very well. Instead, it walks up and down the stem of the goldenrod in search of a mate. After mating, the female lays her eggs inside the goldenrod stem by inserting her sharp ovipositor in the plant tissue. The larvae then hatch in ten days or so, and begin eating the inside of the plant stem. Their saliva contains a chemical that causes the plant to grow abnormally, creating the ball-shaped gall inside of which the fly larvae live.

The larvae stay inside for a full year before becoming adults. When fall approaches, the larva digs an escape tunnel but still does not emerge until the next spring. They stay alive during the winter by producing a kind of internal antifreeze inside. In the spring each larva will become a pupa (rest- ing stage) before emerging as an adult fly.

Goldenrod gall flies have many predators that can locate galls and dig out the juicy snack inside. Downy Woodpeckers and Carolina Chickadees are two birds that actually seek out galls and break them apart to feed on the larvae.

Goldenrod nearly became an industrial commodity during World War I when the price of rubber rose from 20 cents to almost two dollars a pound. Thomas Edison was asked by his good friend Henry Ford to find a domestic source for latex. Edison became quite the botanist, explored many species of plants to determine which might have similar characteristics to the Brazilian rubber tree. He determined that goldenrod actually showed the most promise, but rubber from golden- rod never made it past the experimental stage.

Hopefully, this September you will look at this beautiful plant with its clusters of tiny golden flowers with new appreciation and wonder.

Laura and Hal Mahan are owners of The Compleat Naturalist, located at 2 Brook Street in the Historic Biltmore Village. To reach the shop, call 828.274.5430.