Naturalist’s Notebook: What’s For Dinner?

Do you ever ask your parents, “What’s for dinner?” Each spring I like to spend time looking for caterpillars, the larvae of butterflies and moths. When you are searching, it helps to know what they are having for dinner.

Many of you have probably read the Eric Carle book, “The Very Hungry Caterpillar”. I love to read this funny story to young preschoolers. That caterpillar eats some very strange things, like lollipops, sausage, cherry pie, oranges, Swiss cheese, and a lot more bizarre stuff. Guess what? It ends up with a big tummy ache. Why? Because it is eating junk that no caterpillar would eat!

Then it eats a nice green leaf and it feels all better. It finally found the right caterpillar food.

New, tender, juicy leaves are especially good food for a small caterpillar. There are lots of leaves right now, so how do you know where to look? Some photos with this post will give you clues to help you discover caterpillars in your yard.

It doesn’t bother me one bit if caterpillars snack on my plants, and I end up with eaten leaves. In fact I plant some things because I know I’ll get caterpillars. Then I’ll get moths and butterflies! Most moth and butterfly species use only one group of related plants to lay eggs on. These plants are called their caterpillar host plant. I found caterpillars in oak, elm, and hickory leaves.

I should add something important here. Other people, maybe even your parents, are bothered when caterpillars eat leaves in the yard. Sometimes they spray pesticides to kill insects that eat leaves. Caterpillars are insects. These pesticides are poisons that will kill caterpillars as well as many helpful insects. I try to discourage folks from using these poisons in their yard. If your plants have been treated, forget finding caterpillars.

In your explorations, look for leaves that have been partly eaten with holes in the leaf. Part of the leaf edge, or most of the leaf, may be gone. These holes won’t be jagged; they will be smooth around the edges because many caterpillars this time of year are small. Little caterpillars have small chewing mouthparts called mandibles, and they nibble along the edges of a hole gradually making it larger.Β  Sometimes the holes can be quite small, and sometimes they eat almost the entire leaf. Look at the photos to get an idea what to look for.

Other caterpillars have found a great way to avoid predators. They roll up the leaf they are snacking on. Caterpillars can spin sticky silk, and they use it to hold together the rolled portion of the leaf. That way they are hidden from the sharp eyes of animals that would love to munch on them.

I took two photos of rolled leaves, one a northern red oak and the other a hickory. Notice that the oak leaf is only partly rolled, while the hickory is completely rolled up.

I wanted to see what was in the hickory leaf, so I carefully unrolled it. Sure enough, there was a little caterpillar inside! (See photo, with part of my thumb to give you an idea of the caterpillar’s size.) After I left, it began closing the leaf shelter back up.

You have probably noticed that all the caterpillars I show are a light green color, so they blend in. They are very well camouflaged on the green leaves. All of them will become moths….if they can escape predators, like birds looking for food for hungry babies.

Why are these little green caterpillars so important? In the May 2020 issue of the National Geographic magazine there is a very good article about insects and why many insects are disappearing. The author cites this important example of why caterpillars are so useful. Small birds called Chickadees usually raise 4 or 5 chicks. They feed the youngsters ONLY caterpillars while they are growing up before they leave the nest. It takes over 500 caterpillars to raise a brood of chicks!

I once watched Carolina Chickadees in my backyard carry 19 small green caterpillars to their babies in less than an hour. Little birds depend on little caterpillars.

Now, go out to see if you can find a caterpillar in your yard. If you do, be sure to write about it in your nature journal. Try to identify the plant or tree leaf it is eating. Have fun exploring!

Mr. Bill

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