October 2000
Eaten Alive
Hungry moths threaten to obliterate a munich symbol
Noah Webster, author of America’s first dictionary, and I were both born and raised in West Hartford, Connecticut. In his reference book, under “h,” the word “horse chestnut” can be found. As a child, I often stood in the yard of the small saltbox house in which he had once resided, gazing up at the flowering deciduous trees described in his volume. My immediate fondness for the horse chestnut was surely a result of the fact that these trees, unlike the less exotic maples or oaks that line every neighborhood in town, are not indigenous to New England. I looked forward to spring, when Webster’s chestnuts would burst with large, white floral bouquets. One year, I pinched a couple of the dark brown pods from the linguist’s lawn and gave them to my father to plant on our property.
Little did I know back then that I would make my home in a city where horse chestnut trees are the essence of summer. A beer garden, after all, would be a mere parking lot with picnic tables without the plant’s broad leaves to cool our brew and our backs. Gärtnerplatz would be an unsettling display of park benches and empty brandy bottles if not for the serene setting the Isar city’s beloved flora provides. Those who have lived here for any length of time have come to expect, perhaps even eagerly await, being bonked on the head by falling chestnuts in autumn. Though residents, until now, have taken the local greenery for granted, there is no doubt that the tree is as much a part of what defines Munich as Brez’n and Weisswurst. Adorned with more than 15,000 Rosskastanien, the Bavarian capital certainly boasts the most concentrated population of the flowering tree in all of Germany.
In 1992, a hungry band of immigrants hit town, ones that may change the Munich landscape forever. Cameraria ohridella, or the Chestnut Leaf Miner, a new variety of burrowing moth, munched its way northwest from Vienna, where it has been nourishing itself since 1989. Scientists in the most ravaged European locations — Germany, Austria and Macedonia — are still trying to determine whether or not the moths will eventually destroy the chestnut trees. Environmental groups and individuals are becoming edgier as ever more leaves turn brown long before September. “There is not one tree left that has not been infested,” laments Michael Brunner from Munich’s Gartenbau. In a letter to Mayor Christian Ude, Richard Quass, of the city council, asked “Has it yet been determined whence the insects came, and, if so, did the horse chestnuts there die?” The missive — written as an inquiry but carrying with it an air of desperate pleading — poses a bottom-line question. “Is the city prepared, in an effort to save the chestnut trees in Munich, to allocate the manpower needed to remove the [larva-infested] leaves as they fall, for as long as it takes to find a way to destroy the Miner moths?”
The answers to Quass’ questions are “no” and “probably not.” No one is yet sure how destructive the tiny, insatiable menaces will prove to be. Some beer garden owners claim that, in raking away fallen leaves containing moth larvae, they have at least kept the bugs from spreading. According to the Süddeutschezeitung, leaf removal, while somewhat effective in controlling the spread of Miniermotten, is an undesireable option at this point because, as city gardeners warn, raking away rotting leaves will upset the soil’s natural nutrient balance. In addition, the consensus is that it is too expensive to hire the hands to do the job.
Hard-hit European countries appear to have several choices, none of which has panned out as yet. It is possible to kill the Miner moths with insecticide. The city of Vienna, for example, is currently working with a compound, DIMLIN, that wipes out moth larvae, but is not harmful to humans, birds, bees and even car finish. A landscaping school in Weihenstephan is currently looking into a chemical solution to Munich’s problem, however, injecting 15,000 trees is considered, by many decision makers, to be cost prohibitive. More environmentally friendly alternatives include fly paper-like traps laced with a synthetic female moth hormone to catch male Miners. Though this method proves effective — as Miller moth strips work in home kitchens — constructing traps large enough to hold thousands of male moths is a tricky proposition. Natural predators — other insects, such as ground-nesting wasps, released to eat the Miner moths — are also being experimented with at present. Scientists have not yet found an insect that will take up residence in the chestnuts.
Every spring I try to make a mental note of which horse chestnut trees in my neighborhood flower in pink. By fall, when I could pocket another precious seed for my dad — the one I gave him as a child is white — I have forgotten. Perhaps this year, a cascading chestnut will jog my noggin into remembering — before it’s too late. I am, nevertheless, hopeful that those involved in the rescue effort will strive for success. As Münchner, after all, they could not possibly give up without a fight.
