I have an infestation of army worms. There are thousands of them. They eat every blade of bermuda grass in about a week. The grass eventually recovers, then a new hatch of worms repeat the process. Controlling erosion is a priority and bermuda goes dormant in the winter so I don't want to go through any more time wasting cycles. I have perhaps 4 or 5 acres around the pond. The grass is new this year and just getting established.

The feed store recommends Sevin insecticide, but after reading the label I won't use it. (Extremely toxic to fish and everything else.) So for I haven't found any pond friendly insecticide.

I did treat with BT. Its "organic" so it doesn't hurt the fish, unfortunately the army worms laughed at it.

Anybody know of a reasonable treatment I should try?

Have you checked out diatomaceous earth?

That stuff is all natural and is effective on many insects. Should not phase the fish or wild life. I've only used it around chickens for mites and such, but it worked.

Vortex, I "think" my hay guy uses Talstar for army worms. Extremely costly and destructive little buggers.

We use DE in our chicken and goat sheds as well, but I don't think it works if wet.

I used Sevin and it worked well. Cough. wheeze.

The little SOBs attacked my new grass planted around my new fall last fall and did a lot of damage before I realized what was going on.

Checked the label for Talstar.

"This pesticide is extremely toxic to fish and aquatic invertebrates."

So that's out along with other Bifenthrin based products.


I've never had good luck with DE.

Thanks for the head's up. I just checked, and Permethrin's toxic to fish as well.

Research the active ingredient spinosad. It is listed as an organic controller of caterpillars. It has limited toxicity to aquatic life and is species specific. It is affordable, often sold under the title Monterey Garden Insect Spray.

I would say even with permethrin or bifenthrin products, you are applying to the grass not the pond and outside of application right before major downpour, the amount that would leach into the water would be minimal under normal conditions. In addition with the dilution factor of the pond water can there be much harm to the fish?

Bifenthrin can be toxic, but if dosed properly it can be a very effective and very selective toxin for carp/goldfish while leaving the other desirable fish. However it also can disrupt the aquatic insects and larva at the same time.

That might work. It needs to be ingested, so it is too late f I r this hatch but I'll try it on the next cycle.

Vortex
BT should work on any catapillar. I’ve used it many times on army worms on tomatoes. Maybe yours was “old”.

BT israeli is the specific BT that works on mosquito larvae and can be put in ponds.

BT has a shelf life of 2 years.....

put up some bird houses while you are at it