2 Questions About Using Bacillus Thuringiensis To Get Rid Of Tent Caterpillars In Your Ornamental Trees

In previous years, you may have watched in disdain as webbed tents form on your favorite ornamental trees. As the tents grow, the caterpillars inside of them eat away at the new leaves and flowers and destroy the overall beauty of your trees. Because of this destruction, you may have decided to try using Bacillus thuringiensis (Bt) treatments this year to get rid of them. If so, below are some answers to a couple of questions that you may have about using Bt to get rid of the tent caterpillars.

1.  How Does Bt Treatment Work?

If the name "Bacillus thuringiensis" sounds like something that you should be avoiding, it is because Bt is actually a bacterium. This bacterium, which is a germ found naturally in soil, is deadly to tent caterpillars. 

When you spray the treatments on the tents, the bacteria infect the insects without harming the trees and without putting you at risk of exposure to harsh chemicals. Once the insects get sick, they will lose their appetites and stop eating. Essentially, the bacterial treatment kills them because the caterpillars starve to death.

2.  When Is the Best Time to Apply the Treatment?

Because you want the treatments to be at their most effective, you need to know when to apply the spray. Because the solution contains live bacteria, you should not apply the treatment during the sunniest and hottest times of the day because the bacteria will weaken and die before they have a chance to come into contact with the caterpillars.

Also, since the caterpillars move around during the day, you may not get the chance to spray them all. However, they do congregate in the tents at night after crawling around on your trees during the day.

To treat as many caterpillars as possible without worrying about killing the treatment's bacteria, spray the Bt treatments on the webbed tents in the evening. Doing so will maximize the treatment by allowing the bacteria to infect as many insects as possible overnight while the caterpillars sleep.

Even if you apply the Bt treatment consistently, there is still a chance that you will not be able to get rid of all of the caterpillars, especially if some of your trees are so tall so that you cannot reach the tents at the top. If so, contact a tree and shrub care service to have them inspect the infestation and discuss any professional pest control options that may be available.