See this previous thread: HERE

basic light weight pyrethrens ought to work ...

such as: https://www.lowes.com/pd/Safer-Brand-32-fl-oz-Natural-Insect-Killer/1000329069

dont spray in sun .. on 90 degree days ... reducing the population from horde to a few stragglers is probably good enough ... i would use a pump sprayer to avoid hand cramps .. and it would probably last a week or so in the tank ... for repeated applications wherever you might need such ...

i am not a doctor.. and i do not play one on tv .. lol.. do your own research.. and use all products according to the label ...

ken

im asking.. wont it take a year for the bt to start working???

"wont it take a year for the bt to start working???"

No. The effect is immediate as soon as the cats start feeding on the treated foliage.

It may take a day or three but the cats will die. The older the cats the longer it takes.

tj

i sure hope hope you are using cats without a period as an abbreviation for caterpillars ...

i must be thinking about bT used in the soil ??????

ken

There are different strains of Bt that target different pests. Bacillius thuringiensis var. kurstaki is the one used to control caterpillar-like larvae. And this is used only as a foliar application.

Thanks, all. There was only one reply last night before I ran out to the store to get something -- I bought Bonide Capt Jack's Deadbug, which is spinosad. Sprayed the cr*p out of the shrub this morning - remains to be seen whether I'm going to find skeletons of the dead SOBs or another skeletonized spruce...

The spinosad should work just as well as the Bt....and even has a slightly longer period of effectiveness.

Good luck!!

I did cut the blooms off the peony that is right next to the spruce since apparently the spinosad is highly toxic to bees for a few hours after application -- thought it would be best to remove so nothing close by they would forage on.

Try Dipel. Good for crawling insects.

mxk3 wrote preferably with the least amount of harm to everything else. This sentiment is very much appreciated. Natural Predators for Gypsy Moths? Cuckoos is a good article about the cuckoo which is abundant around here. They are elusive but their low call is easy to identify.

In my Bagworm War thread I recommended Thuricide which is labled for gypsy moth. It contains BT which is lethal to leaf eating caterpillars but not harmful to anything else.

THIS youtube shows yellow-billed cuckoo with his favorite meal. They eat caterpillars almost exclusively including GM caterpillars.

VERY exciting, sam. We have two cuckoo species in our state. Here's hoping they have a banner year! (But not by eating the monarch caterpillars, if I could be so demanding. ;-D )