Fern Glen Essays
They've Got a Lot of Gall
by Judy Sullivan

It's a typical winter's day. Fields white with snow, roads white with salt. Biting cold drives the mercury to cruel depths. Savage winds shake the trees. Snug in your home, but hungry, you turn your head and bite the wall. Thankfully, there's no need to venture out. After all, you're living in a loaf of bread. A yeasty boudoir that never grows stale. Indeed, the walls replenish themselves. What magic is this? What fairy tale? All a matter of course (first, second or third) when you're the grub (no pun intended) of the goldenrod gall fly.

It starts in late May, a month of wonderful beginnings. A freckled female fly has a ticking biological time clock of two weeks duration. After responding to the attentions of young male, she sets out to find the perfect spot to set up a nursery. This is not a simple task. For this young female is Eurosta solidaginis, the goldenrod gall fly. Her name indicates her association with the Solidago, or goldenrod plant. Although this is specific indeed, not just any goldenrod will do.

The young mother selects her plants with care. She treads gently, tastes with her feet, and then inserts her ovipositor (a romantic name for a thin, sharp egg tube) into the tip of the stem. However, as soon as the point of the tube pierces the first layer of leaves, she realizes that there is something amiss. Some fool scientists have wrapped the leaves of the Canada goldenrod around buds of other goldenrod species. This is no time for practical jokes. She withdraws her tube and continues her quest for the perfect stem. Only the tall goldenrod (S. gigantea) or Canada goldenrod (S. canadensis) will provide the right environment for her eggs. She reflects that the mothers of the scientists should have experimented on them. Then again, maybe they did...

After an arduous walk (those cute wings are more fashion than function), she locates Solidago canadensis. However, she's faced with one more crucial test. Is it a good Canada goldenrod? Even within the right species, not every plant will welcome her eggs. She tastes, stabs the bud with her egg tube and, after this final approval, injects a single egg. One down. Ninety-nine to go. No wonder she has no sense of humor.

Meanwhile, inside the stem of that one plant, the gall fly egg hatches in just over a week. The little larva chews and burrows its way further into the stem. There it simply settles down to the process of growing. In response to the presence of the larva, the goldenrod begins to form a round growth, or gall, that supplies its guest with food. Crusty on the outside, chewy on the inside - a living loaf. As the walls are reduced by munching the plant grows new ones, providing a steady supply of meals. Despite the plodding maternal dedication of the fly, I'm most struck by the behavior of the goldenrod. A constant supply of food to something that lies around and grows. Sound familiar? At least it doesn't play basketball in the house...

During this marathon of egg laying, mom hasn't stopped to eat a bite. It's not surprising that, at the end of approximately two weeks, she's worn out. Marching up and down stems and jabbing her ovipositor like a lance into tough tissues takes its toll. It would be satisfying to report that she sinks into a hot bubble bath with a vapid novel, a chilled glass and a deep sigh. Nevertheless, this is not only a cautionary tale, but a true one, as well. She dies.

Next week: danger knocks without

Questions, comments, or other feedback to Judy Sullivan.