Inchworms aren't worms, but are actually caterpillars that belong to the Geometridae family of moths. This family is of the order Lepidoptera and is known to have about 35000 different species in the world. Furthermore, about 1,400 kinds of geometer moths are known to live in North America. These caterpillars are also referred to as loopers, spanners, or measuring worms.
Read on to discover inchworms' peculiar movement, the story behind their unusual name, and fun details about their appearance, habitat, eating habits, and life cycle.
Appearance
Inchworms are small, hairless caterpillars with fewer legs than most other caterpillar species.
They grow to about 1 inch (25 mm) long and can be green, brownish, gray, or black. The color usually depends on the species of moth they will grow into.
Some have black spots on their head.
Their legs are found only at the very front and back of their body, there are none in the middle.
Locomotion
The term Geometridae is believed to have come from a Greek word meaning 'earth-measurer'. This meaning can be applied to the peculiar movement that inchworms have.
Because they have no legs in the middle of their body, they move in a looping motion. First they pull their back end forward to form an arch, then they stretch the front end forward again.
Habitat
Inchworms live in regions with a mild, temperate climate.
They stay close to their food sources, you'll often find them on oaks, lindens, elms, maples, apple trees, and other fruit trees.
Defense Mechanism
Inchworms have several predators, including birds, lizards, and wasps.
When they sense danger, they freeze completely and hold their body stiff, looking just like a small twig.
Their skin has markings that mimic bark or leaf scars, which makes their camouflage even more convincing.
They can also spin silk and use it as an escape rope. If a predator comes too close, they drop quickly from the leaf and hang in the air on a thin silken thread. Once it's safe, they climb back up and carry on eating.
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Eating Habits
One inchworm doesn't eat very much on its own. But a large, hungry group of them can cause serious damage to trees and bushes, especially apple trees, mulberry bushes, and garden plants.
Most species feed on the leaves of deciduous or coniferous trees. Some eat lichen, flowers, or pollen instead.
There are even a few carnivorous species! Certain Hawaiian inchworms of the genus Eupithecia ambush and eat small insects, making them among the only caterpillars in the world that hunt other animals.
Cankerworms are a type of inchworm that can be very destructive to orchards and gardens. Farmers and gardeners often use a natural bacteria called Bacillus thuringiensis to control them safely.
Frequently Asked Questions
Are inchworms actually worms?
No, inchworms are caterpillars, the larvae of geometer moths in the family Geometridae.
Why do inchworms move the way they do?
They have no legs in the middle section of their body, so they loop their body forward by pulling their hind end up to their front end.
What do inchworms turn into?
Inchworms grow into adult geometer moths. They spin silken cocoons and pupate underground before emerging as fully grown moths.
How do inchworms protect themselves from predators?
Inchworms freeze and mimic twigs using their bark-like markings. They can also drop quickly from leaves on a silken thread to escape danger.
How many species of geometer moths exist?
The Geometridae family has about 35,000 different species worldwide, with around 1,400 kinds known to live in North America.
Life Cycle
Inchworms live for about one year in total.
They grow up to become adult geometer moths. Fully grown, these moths measure anywhere from 3/8 of an inch to 2 inches across their wingspan.
Male moths have wings and can fly. Female moths are wingless, they wait on tree branches while the males come to find them.
Unlike most moths, geometer moths hold their wings flat and spread out when they land, similar to a butterfly. Most other moths fold their wings like a tent over their body.
Most geometer moths are active at night, but some species fly during the day too.
In winter, adult moths lay large clusters of gray, cylindrical eggs on tree branches. Each species produces one generation per year. The eggs hatch in spring, and the larvae feed on leaves for about 5 weeks. Then they spin silken cocoons and pupate underground. When the adult geometer moth emerges, the whole remarkable cycle starts again.
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Fun fact for today!There's a fitness exercise called the "inchworm", named because it copies the caterpillar's up-and-down looping motion!