water lily pests

by George
(Tunbridge Wells, UK)

My pond lily and pond weed have been devastated by small worms,light brown, 5mm long. I have drained the pond twice but they persist and have been around now for approx. 5 years. Help please!

Doug says that he doesn't know which worm this is but it sounds as if you have some caterpillar larva trying to make lunch of your plants. The quick way to deal with them is to go to your favorite pond store and get some Bacillus thuringiesis (Bt) that is suitable for ponds. Some is designed to kill the water stage of mosquito larva and lives nicely in water. I'd dust the plants with this. Once the larva eat it they should stop feeding - although it usually takes 3-5 days for them to actually die (but they don't eat in the meantime)

Hope this helps even though we can't id the pest without a pic.