Water hyacinth damage

[Bill Smith]

Hi there:

I'm really loving using the water hyacinths in my ponds, but in a couple of them, I'm noticing some pretty heavy pest damage:

I found some 1" sized back and grey caterpillars, so it's clearly a moth or butterfly of some kind laying eggs on the plants.

My question is, has anyone had any decent luck with any kind of treatment or pesticide that makes them less appealing to the critters, but is also pond safe? I don't mind mixing up a spray bottle of something, but I don't want to poison my ponds.

Thanks for any suggestions you can offer!

Bill

[Brandy]

Caterpillars would be a good candidate for Bacillus thuringiensis spray, which should be fish safe. It will however also take out mosquito larvae, and blackfly larvae, and so on, you may want to avoid it in your daphnia set up. Or not, it should only bother larval stages of insects.

Alternatively hand pick and squish and feed to fish!

Edited August 22, 2020 by Brandy

[Bill Smith]

3 hours ago, Brandy said:

Caterpillars would be a good candidate for Bacillus thuringiensis spray, which should be fish safe. It will however also take out mosquito larvae, and blackfly larvae, and so on, you may want to avoid it in your daphnia set up. Or not, it should only bother larval stages of insects.

Alternatively hand pick and squish and feed to fish!

Good advice, thank you! I have lots of bubbles and moving water, so I don't expect much larval activity anyway.

I will give it a shot and report back! 

Do you think I should cut off the affected leaves or let them be?

[Brandy]

I think it all depends on how much they bother you. They will keep making food for the plant. If they are too ugly you can cut them off entirely or just trim them into less "eaten" looking shapes, or you can wait for them to die back on their own.