The name says it all. Tomato Armyworms show up in droves to consume the leaves and ruin the fruit of your beautiful tomato plants. They will eat the fruits wether green or red, they turn leaves into lace.
There’s several species of armyworm caterpillars, some of which prefer a certain plant but many of which will eat anything green, red, or yellow. Armyworms tend to be most active at night, and hide under leaves and in debris during the day.
Greenhouses crops can be especially vulnerable to armyworms because of a lack of natural predators such as birds and parasitic wasps. It is important to take special care to keep moths excluded from the greenhouse in order to avoid an armyworm infestation. Early detection aids in preventing armyworms. Watch for masses of eggs covered with fluff, small caterpillars feeding in groups or single large caterpillars with a yellow stripe running down their sides.
So once you have them, how do you get rid of them? Here are a few ideas for the organic grower.
- Pick them off when you see them. It sucks to smush the little buggers, but it works. You can also get a cup or bucket with soapy water and drop them in to kill them.
- Bt Dust. Bacillus Thuringiensis contains a natural toxin that kills most types of caterpillars that feed on garden plants. The toxin doesn’t harm humans or animals. When a caterpillar eats a leaf that has been treated with Bt, the toxin destroys the wall of the intestine so that the gut contents spill out into the body cavity. Armyworms that eat Bt are no longer able to eat, and they die in a few days.
- Release beneficial insects (ladybugs, trichogramma wasps, lacewings, pirate bugs, etc) in your garden. For example, trichogramma wasps, parasitize any newly laid eggs. These tiny beneficial insects — 1mm or less — insert their eggs inside of pest eggs, killing them before they enter the plant-eating larval stage.
- Spinosad Spray. Spinosad is a natural substance made by a soil bacterium that can be toxic to insects. It is used to control a wide variety of pests, in addition to armyworm caterpillars.
- Create good habitat around your growing area for birds. Many types of birds will keep the caterpillar population in check for you.
- Neem Oil. Not a great choice for the larger caterpillars, but suitable for the eggs and small larvae.
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