Does neem oil also work with hornworms?

[pointer80]

Hello all, I am just curious if neem oil will work for hornworms considering they are a chewing insect? I thought that's how neem oil worked? If not then why? I am just curious?

[imafan26]

Oils and soaps work on mostly soft bodied arthropods and young larvae. It is also an antifeedant. It can work on caterpillars with the right dilution rate, but you still have to cover the insects to smother them.

Horticultural oils and soaps work on sucking insects as well as some chewing insects. They are primarily contact sprays that work by suffocating insects by irritating or blocking their breathing holes. Most have little residual so if an insect comes by a day later, it won't be killed. Neem breaks down in sunlight in a few hours. Neem can be very toxic to bees if it is sprayed on flowers. Bees collect nectar and pollen. Pollen is fed to young bee larvae and neem sprayed pollen can kill bee larvae. Neem should not be sprayed near water since it is also very toxic to fish.

Soaps and oils are less effective on hard bodied insects like beetles and mites (which are tiny spiders) and insects with protective coatings like adult scale, spittle bugs, and whiteflies. These sprays are not very effective on anything that is able to fly away like adult whiteflies.

Bt is effective on most caterpillars, hand picking, physical barriers, kaolin clay, insect eating birds, geckos, parasitic wasps are other ways to control caterpillars and some other more hard bodied pests. It helps to rotate crops so they are not planted in the same place every year, inviting pests to the buffet. You will need to check the surroundings for alternate hosts and control pests on those plants as well. It may not be possible to avoid all pests but if you have a butterfly garden and grow butterfly weed, butterfly bush, milkweeds and other nectar and host plants, you will have more problems and have to protect the crops with insect barriers or if you can, plant some crops out of season when the pests are less active.