It’s late july here in ohio, and you’re expecting your tomatoes to be ripe with bright red fruit, so you go out into the garden and discover they’re all gone; the plants is literally stripped clean. It’s too much to take, as if nature has betrayed you, but more often then not, the culprit isn’t even nature at all, but hungry (and very particular) caterpillars.
Here’s how to know: To defeat these tomato-stealing pests, you don’t have to remove each and every single one. First, identify who’s there, and whether they’re worth saving or they’ve come to steal the harvest. Knowing the difference mean no harm to the environment around here, just a big relief for you and your crops.
How to Identify Garden Caterpillars
First, examine the location of the caterpillar: Are you on a milkweed? A bright-green larva will likely be a Monarch, not a bad bug, because most species are picky eaters; I will talk more about that shortly. Because knowing your host plants is the key to starting off right in any ID, the visual above points that out clearly. It also shows another important aspect. Knowing where the caterpillar lives, which is often on certain plants like these milkweeds, is the first clue in the ID puzzle. This can help you quickly identify what it might becomes later.
On kale and other brassicas, for example, such as cabbage, keep an eye peeled for those loopers that arch their back end up into a bridge position when they travel. Why? Because they don’t have many mid-body prolegs (that’s why the gait looks looped in the middle; the front and rear ends is all legs, though). Once you’ve seen one do that, you’ll see it again easily among foliage.
Size is another good clue. At four-plus inches long, the adult tomato hornworm, though well camouflaged on green leaves, is difficult to mistake for anything else. Look for the prominent rows of white, running up and down in diagonals, plus a sharp-pointed red end that resemble a danger-warning flag. If your pest is very small (the corn earworm starts tiny but bores directly into the kernels of sweet corn before you even realize they’re there), it will do more subtle damage than a big, leaf-eating creature, and much sooner.
Knowing which species likes to chew what, how fast they progress, and when they do so: That’s what makes the difference between a nuisance and a disaster. Some plant pests eat from the outside-in by chewing holes in leaves. Others go deep into fruit or stem tissue, making them harder for us or other predators to find and remove.
And then there are the fuzzy ones that make us want to flinch right away. Around here we know our woolly bears, who famously cross the road in late fall, supposedly their orange band width predicts winter severity. Who knows, but at least it won’t hurt to pick one up (with a stick, not your bare hand), as they’re harmless.
Other hairy caterpillars aren’t so accommodating. Several species has urticating hairs or stinging spines, says the infographic, which can cause painful skin irritation. I’ve encountered one called the saddleback caterpillar. Its body is brown and marked with a bright green “saddle,” making it look kind of decorativ. But don’t be fooled: they’re covered with venomous spines that sting sharply when touched. Assume any new secretly crawling fuzzball is protective; better safe than sorry. One little safeguard, no trips to the pharmacy necessary.
Understand the life cycle to know when to act. For example, caterpillars hatch from eggs that are deposited, yep; on their favorite foods. So if you scout extra-early, while the egg is hanging out, you can prevent a feeding frenzy before it begins. Once hatched, the larvae go through a series of molts (called instars) during which they quickly grow and eat nonstop until fully formed. This is when you’ll see the damage… But this is when targeted treatment, or even just manual removal, will be most effective. If you wait any longer you’re fighting pupae hiding in the tree bark or in the ground, and they are well protected against most tactics.
You should of waited for more signs. Your expectations are governed by seasonal patterns as well. For instance, fall armyworms hits fields of corn at the end of the season, after most other things have peaked. Tent caterpillars gather in silk nests on fruit-tree trunks (on apples and cherries) in springtime. The more familiar you become with these seasonal rhythms, the less reactive you’ll be to any apparent damage. You will be better able to remain one step ahead instead of scrambling around in a panic.
Don’t expect to learn all the names right away. Begin with the ones affecting your particular plants, then add others as you go along. It’s not about a bugless garden, but one that works together to protect crops while at the same time supporting those beneficial butterflies and moths. Get to know the faces of the good guys, look out for the telltale signs of the bad, and handle difficult situations with care.
The bees (and your tomatoes) will thank you.