Too Much of a Good Thing?

Already this spring [2001] the B.U. Horticulture Hotline (HortLine) has received many calls about nightcrawlers, the large earthworms found in gardens and yards. These huge worms are not harmful; in fact, they are beneficial to the soil. Nightcrawlers perform the same function as ‘regular’ earthworms, composting and aerating the soil. However, they tend to be slightly over-zealous in their work, and the castings they leave behind cause hard bumps to form in lawns. Some residents find walking on and mowing their worm- rich lawns a very rough ride, causing them to seek treatment.

Control: Short of going into the fishing-bait business, few documented solutions exist for nightcrawler overpopulation. There are no chemical treatments specifically designed for their control. However, insecticides such as diazinon, malathion, or endosulphan are reported to be effective. Two fungicides, Benlate and ridomil, have also been found to be somewhat effective against nightcrawlers. When considering treating nightcrawlers, remember that they are good for the soil.

Compiled by Dr. Bill Paton and Shauna Peters