Bt (Bacillus thuringiensis)

[Bowfin]

A question for the experts out there-

The tent caterpillars are coming and I would like to control them and other worm and caterpiller pests on my apple trees but am hesitant to spray some of the chemical insecticides on something I'm going to eat. I know in forestry (gypsy moth) there is wide spread spray of Bt (Bacillus thuringiensis) to kill caterpillars. This is the natural fungus found in soil that is toxic to caterpillars. Is there any products with Bt available to the homeowner for small applications?

Does Bt control slugs in the garden?

[bobbymalone]

i've seen it on the shelf called "thuricide" before.

Also, Bacillus thuringiensis is a bacteria not a fungus. and it's protein the bacteria makes that is purified and used as an insecticide. the gene that makes that protein was taken from the bacteria and inserted into the genome of field corn so that the corn plant itself makes the toxin.

It works on insects and various larval stages thereof. I'm thinking it would be no good for slugs.

[Dotch]

Thuricide is one brand name of Bacillus thuringiensis and not all of the Bt's contain the same strain of bacteria. For instance the Bt that will control a beetle in the case of corn rootworm will not control corn borer. The strain you'll need to contain tent caterpillars is Bacillus thuringiensis var. kurstaki. Bt's are fairly specific as to what species they will control even within the same order and family so it will be necessary to read the label to see if the organism you're after is listed for control. One other downside is they may need frequent reapplication if we encounter stretches of rainy weather. And no they will not control slugs. The first link below offers some slug control options. Hope this helps.

http://blog.lib.umn.edu/efans/ygnews/2009/04/a_brief_survey_of_insecticides.html

http://blog.lib.umn.edu/efans/ygnews/2011/06/tent-caterpillars.html

http://www.extension.umn.edu/distribution/horticulture/DG7563.html

[flipper]

I use a blow torch.

[Eric Wettschreck]

I had a huge blob of tent caterpillars all over my apple trees a couple years ago.

I just jumped on a ladder and ripped em all down. Once on the ground, the ones the dog didn't eat I hit with the torch. They never came back.

[reinhard1]

. good luck.

[Dave S]

I spray the nests with Sevin. Bought it at the 'Nards store in Mankato. It works if you get it on the nest and saturate it good. They still tend to come back every year and have claimed one tree in the yard already.

[Dotch]

They're an annual occurence especially in the fencelines on the wild plums around here. I had some tents on the small Mt. Royal plum the other day that were small so I smushed 'em. Always nice to see my fellow sadistic pyromaniacs weigh in though...

[flipper]

Always nice to see my fellow sadistic pyromaniacs weigh in though...

Give me barbecued caterpillars but leave me the birds and the bees yeah.

[fishinsfun]

Up here in the northland, these buggers come in cycles. You might remember the last peak from 2001-2003 where they literally covered everything up here. We are on track for another peak soon, but not expected to be nearly as bad.

Depending on how many trees you are talking about, you can simply remove them as others have alluded to. As Dotch said, Bt is fairly specific, but you could affect other desirable caterpillars that become desirable moths or butterflies. Unless you have many trees where hand removal is not an option, avoid Bt. Even the folks targeting the Gypsy moth are careful how much they use for that reason (and they have some other interesting control techniques based on the males 'desire'!).

Also, Sevin is not something I would use haphazardly (not suggesting anyone is). It is broad spectrum and will target desirable insects such as honey bees. Use sparingly.