My eastern redbud has caterpillars

[XemaSab]

Last year they completely hammered the tree.

How do I get rid of them? :shrug:

[Kolesar]

1. I sprayed Bacillus thuringiensis (Bt) to control cabbage moth larvae

The article discusses effectivity on woody plants. I have not studied this intensely.

http://www.entomology.wisc.edu/mbcn/fea207.html

The Insect Pathogen Bacillus thuringiensis

Bacterial pathogens used for insect control are spore-forming, rod-shaped bacteria in the genus Bacillus. They occur commonly in soils, and most insecticidal strains have been isolated from soil samples. Bacterial insecticides must be eaten by target insects to be effective; they are not contact poisons. Insecticidal products composed of a single Bacillus species or subspecies may be active against an entire order of insects, or they may be effective against only one or a few species. For example, products containing Bacillus thuringiensis var. kurstaki kill the caterpillar stage of a wide array of butterflies and moths. In contrast, Bacillus popilliae var. popilliae (milky disease) kills Japanese beetle larvae but is not effective against the closely related annual white grubs (masked chafers) that infest lawns in much of the Midwest. The microbial insecticides most widely used in the United States since the 1960s are preparations of the bacterium Bacillus thuringiensis (Bt). Bt products are produced commercially in large industrial fermentation tanks. The bacterial cells usually produce a spore and a crystalline protein toxin - called an endotoxin - as they develop. Most commercial Bt products contain the protein toxin and spores, but some contain only the toxin component. When Bt is ingested by a susceptible insect, the protein toxin is activated by alkaline conditions and enzyme activity in the insect's gut. If the activated toxin attaches to specific receptor sites, it paralyzes and destroys the cells of the gut wall, allowing the gut contents to enter the insect's body cavity. Poisoned insects may die quickly from the activity of the toxin or may stop feeding and die within 2 or 3 days from the effects of septicemia (blood-poisoning). Bt does not reproduce and persist in the environment in sufficient quantities to provide continuing control of target pests. The bacteria may multiply in the infected host, but because few spores or crystalline toxins are produced, few infective units are released when a poisoned insect dies. Consequently, Bt products are applied much like synthetic insecticides. Bt treatments are inactivated within one to a few days in many outdoor situations, and repeated applications may be necessary for some crops and pests.
...more...