Would Diatomaceous Earth work for spraying unreachable Tent Caterpillar nests?

Question

In trying to help answer another person's question, I realized that I have one of my own.

I try to manually remove the tent moths from my trees every year, using both a step ladder and extension ladder. But, I still can't reach them all. I live in Virginia, USA.

How effective/harmful would spraying Diatomateous Earth in liquid form be (using a hose sprayer) be on those tents that I can't reach, so that they don't spread? We would only be specifically spraying the tents. (And no, I don't use it in my gardens or yard, myself.)

I have a very sweet neighbor who has different views on things. (He loves grass. Not gardens, bugs, and birds.) We have always been able to compromise, and he no longer sprays pesticides and weed killers onto my property with his hose, but we do have some trees that border our properties, and I am hoping to come up with a solution that will make us both happy this year.

I welcome any and all advice (including alternative solutions) as an answer to this question! Thanks.

(Added info) The hose jet-streaming method (although being the ideal solution) has not worked to break open these tents unless you are pretty close to them. It doesn't work on the higher tents, even when I am trying to shoot them from a ladder, with the strongest water pressure that we have.

Answer 1

I don't know if Diatomaceous Earth will work but I see a couple of problems with using it that way. The way DE works is that it physically injures the bugs so it works better with crawling insect that will crawl through it. They're small creatures so to them it would be similar to us having to crawl through glass shards. Even if you get it up on the tree by spraying in a solution, it may wash away in rain. DE is also harmful to breath in as is most fine dust so I don't like the idea of spraying it on a tree.

One alternatives is to physically remove them. If you can't get up with a ladder you can try using a pressure washer or a different nozzle which may be more effective than your previous attempts with a hose. If you don't have a pressure washer you can try some of the high pressure hose end nozzles like Little Big Shot or Bulls Eye. They're both small nozzles that look something like this and at least Little Big Shot is available at places like Home Depot.

Additional organic controls are Bacillus thuringiensis and neem oil. You can even try to attract more birds to the area which are predators of tent caterpillars.

One strain, Bacillus thuringiensis israelensis, is what's in Mosquito Dunks. Bacillus thuringiensis is a bacteria that is used as a biological pesticide and Bt can be used on tent caterpillars but the caterpillar must ingest it. The city of Seattle uses Bt to control tent caterpillars as a secondary method to mechanical removal. There's some good info on that page.

Neem oil is another choice that seems to work and some products indicate they can be used on tent caterpillars on their label.

I would try mechanical control first. If you then decide to go with a pesticide, follow proper safety procedures when applying.

Answer 2

Diatomaceous earth as an insecticide requires that the bugs slide across the surface of the DE which then acts as little razors shredding their epithelial layers so that they lose the ability to retain fluids, and so dehydrate and die.

So, if your caterpillars are hiding in a nest, and don't come out, it won't affect them.

Maybe you can use a high pressure hose to open up the nest to let birds get them.