From the Viette's Views Gardening Blog
I saw the tell-tale signs up in the orchard yesterday – the beginnings of the familiar, yet dreaded tent caterpillar webs starting to form in the crotches of one of the apple trees. It wasn't very big yet but everyday it will grow … little webs will grow into bigger webs; little caterpillars will grow into big leaf-eating machines crawling over the branches devouring every bit of green foliage on the tree until it looks like winter has returned! Nasty little critters! I know they must serve some purpose in the greater scheme of things but I sure haven’t figured out what that might be – food for the birds, I guess.
Yes, I’m sure that must be why they exist!
“Knock ‘em out while they are small”, Andre always says. It’s the best time and you don’t have to resort to using chemical insecticides.
Wage biological warfare!! When they are small, they can be eradicated with a lovely little bacterium called Bt (short for Bacillus thuringiensis). Bt (also sold under the trade name Dipel) produces a natural insecticide and has been used by organic farmers for years to safely control many insect pests. Just spray it on the foliage and when the caterpillar eats the leaves, they ingest the Bt which produces a toxin that basically dissolves their gut and kills them within a few days – no harm to the environment or beneficial insects! And … even though it takes a few days for the caterpillars to die, the best part is that they stop eating within a few hours so your trees are saved from defoliation! Good stuff – and environmentally responsible, too! Look for Bonide Thuricide (BT) Liquid Concentrate or Dipel; they should be right on the shelf of your full service garden store.
If you miss the younger ones, larger caterpillars can be controlled with Bonide Captain Jack's Deadbug Brew according to label directions. NEVER spray any insecticide when trees are in bloom!
Watch this Viette video tip for another interesting way to get rid of tent caterpillars! Along this line, you can also poke a stick into the web and wind the web, caterpillars and all, up on the end of the stick and then stomp them into the ground!
Ahhhhh – revenge is sweet!
Bonide products can be found in most full service garden centers.