In the early part of the last century, Ash trees were a popular replacement in areas devastated by the Chestnut blight. Ironically, today the Ash tree may face similar devastation. Since its accidental introduction into the United States and Canada in the 1990s, the Emerald Ash Borer has spread to more than 14 states and large parts of Canada. The little green menace has left an estimated 50 to 100 million dead Ash trees in its wake.
The EAB isn’t picky, and that’s what makes it so destructive; it eventually kills all species of Ash. Even worse, EABs attack trees as small as one inch in diameter, well before young trees have a chance to set their own seeds. Field studies of Michigan forests infected with EAB show the borer will kill every single Ash in the forest, causing some scientist to whisper the dreaded ‘e’ word – extinction.
In the past decade, a number of techniques have been used to fight the EAB including numerous insecticides and quarantine of infected areas. But unfortunately, most have only served to slow the progress of the borer. The EAB seems unstoppable in part because the Asian native faces little natural controls in North America – at least until now.
Canadian officials have just approved the importation and release of two Asian wasp species tested in Michigan in 2007. Though some scientists have understandable reservations about introducing another non-native specie, laboratory tests show the wasp only lays grub-killing eggs in the EAB grubs.
Unlike wood bans and insecticides, the wasps aren’t dependent upon individual cooperation and collective financing; they’re an army of self-propagating EAB hunters. If successful, we may be able to curtail the EAB in time to save many Ash trees, and avoid the long arduous restoration process we’ve faced with the American Chestnut.