The worms you are talking about are really caterpillars. There are several ways to get rid of the pests naturally. The first is to use a pesticide with the active ingredient bacillus thurengensis. Bacillus is a bacterium specific to caterpillars. Once they infect the caterpillar, it stops feeding and dies within days, releasing more bacteria to infect unsuspecting caterpillars that crawl over them or take a tainted munch. Caterpillars are the bacteria’s only food. They aren’t interested in you or any of your loved ones, including your pets. Several brands of pesticide use bacillus as the active ingredient. The spores stay active until washed or blown away.
Pyrethrum is a natural insecticide gathered from a relative of the chrysanthemum. It is lethal to cold-blooded animals, such as insects, fish, amphibians and reptiles, although it is harmless to warm-blooded animals, such as birds and mammals. (Disaster would strike the U.S. government if it was sprayed over Washington D.C.) Pyrethrum sprays can be used as a general insecticide. The spray knocks out any exposed caterpillars, and then disintegrates to harmless compounds within a couple of days.
Of the two products, I prefer the bacillus because it targets the pest and doesn’t affect the rest of the living community. A problem common to both pesticides is contact. They kill pests exposed to them but not the caterpillars that are already inside the stem chewing a path of destruction. If you can figure out where they entered the plant, just poke holes in the stem above and below to inject some pesticide into the stem. It could be done with a spray or an eye dropper. If you can figure out where the crawlers are, you can always go for the direct hand kill.
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