Bad Caterpillars v Good Caterpillars

A Quick Overview of this Blog Post

As you presumably know, caterpillars are the larva of either moths or butterflies—and their sole purpose at this particular stage in their development is to eat. And eat, they do. What’s more is this: Because nearly all caterpillars are plant eaters (with very few exceptions), caterpillars can cause quite a bit of damage to your plants.

Because there are more than 12,000 species of moths and butterflies in North America alone, we won’t attempt to list them. Instead, we’ll talk about how to how to control bad caterpillars, we’ll identify a couple of caterpillars that are usually considered “good caterpillars” and we’ll also provide a link to help you to identify the caterpillars that you find around your yard.

Bad Caterpillars and How to Control Them

What makes a caterpillar a bad caterpillar? “Bad caterpillars” do substantial harm to your gardens, oftentimes by targeting specific plants and trees. They damage – and even destroy – your greenery.

That’s definitely not good. So, if you are seeing more destruction in your garden than you can tolerate from these voracious eaters, your caterpillars have gone from at least being a neutral presence to a bad one.

Caterpillars damage plants by chewing on fruits, flowers, shoots, and leaves, and signs of caterpillar damage include holes, rolled or webbed leaves, eggs, and excrement. This kind of damage is easy to spot, but caterpillars can also bore into wood, and finding wood-borers can be difficult. Therefore, it can be hard to control caterpillars in trees until substantial damage has been done.

While caterpillars do have their place – both as pollinators and as prey in the food chain – you simply may not want them in your gardens due to the destruction they can cause.

1. Controlling Bad Caterpillars

Caterpillars are pretty low on the food chain, and their soft bodies tend to make them easy prey for birds, insects and small mammals. Because of this, caterpillar populations are often kept in check organically and, typically, discovering a few caterpillars in your garden is of no great concern.

However, if you’re seeing growing signs of caterpillar destruction in your yard, there are things that you can do to manage them.

1. Pick the caterpillars and immerse them in soapy water. Remember to wear gloves because some caterpillars can sting.
2. Buy something called Bt – which is an insecticidal bacterium (Bacillus thuringiensis) at your local garden center. Bt is nontoxic to human, pets, bees, beneficial insects and other wildlife. Simply spray it directly on any caterpillars that are causing damage.
3. Use sprays containing Pyrethrum when caterpillars are attacking vegetables.
4. Do a little research on the Planet Natural Research Center for more organic methods of controlling caterpillars and other pests.

2. What Are “Good” Caterpillars?

Good caterpillars, to many people, are the ones they intentionally try to attract because they will turn into beautiful butterlies, like Monarchs. Check out The Butterfly Site’s list of butterflies that call Illinois home to help you determine which butterflies you’d like to find in your butterfly garden.

3. How to Identify Your Particular Caterpillars

Discoverlife.org offers and easy Caterpillar Identification Tool. We suggest that you take a picture of the caterpillars you’re dealing with and then use their 4-point guide to tick off identifying features. You’ll then be presented with thumbnail images of the caterpillars that match the characteristics you’ve selected. Scroll through those images until you find the caterpillar that matches the one you are trying to identify.

The Wrap Up

Armed with the resources above, you should be able to determine which kind of caterpillars you are seeing in your gardens, whether they are desirable or not and how to control them.