Inchworms are not worms; rather, they are caterpillars that are a member of the Geometridae family of moths. There are around 1400 different kinds of geometer moths living in North America alone. Inchworms are also called loopers, spanners, and measuring worms.
The characteristic that is most obvious is that inchworms have fewer legs than other worms, which results in their unique movement. They can cause damage in a garden, especially in large numbers.
Characteristics of Inchworms
Inchworms are small and lack hair. They are around one inch long and they come in different colors including green, brown, gray, or black. Their color determines what type of moth they transform into.
Their legs are on the front and back portions of their bodies with no legs through the middle. To travel, they must pull their hind legs forward and form a loop in their bodies, and then they move their front legs forward to keep moving.
Inchworms live in areas that have a moderate climate and they need to be near food sources, which includes deciduous trees such as elm trees, apple trees, maple trees, linden trees, oak trees, and other fruit trees.
Their natural predators are birds, wasps, and lizards and they can freeze and resemble a twig when these predators are nearby. Their coloring allows them to freeze and blend in with trees and leaves.
In addition, inchworms produce silk and they can drop down from leaves and hang on the end of the silk when they are in danger. They also are able to camouflage themselves with leaf scars or bark to protect themselves from predators. Once safe, they return to their task of eating.
What Do Inchworms Eat?
Inchworms eat the leaves on different trees, bushes, and garden plants. Each individual inchworm does not eat very much but when there are many of them, they can cause major damage.
Most inchworms eat the leaves of coniferous and deciduous trees such as oaks, maples, apple trees, elms, linden trees, pines, fir trees, and other fruit trees. One species, cankerworms, are very destructive and farmers actually go to great lengths to control them.
One of the reasons why inchworms can be so destructive is that they feed on leaves during the day and the night. They eat young leaves, flower buds, fruits, and berries and they leave large holes in leaves or fruit. They hatch from eggs in the spring and they can defoliate an entire tree if there are enough of them present.
One of the problems with the damage that inchworms cause is that they reduce the ability of these trees to engage in photosynthesis as the leaves are critical for this function. Photosynthesis allows the trees to take the energy from sunlight and make their own food. They cannot survive when this ability becomes compromised.
How to Control Inchworm Populations
Inchworms take around four or five weeks to transform from an egg to a mature moth. They spend their entire life feeding on the trees where they live. If there are many of them, it can be necessary to control the population to minimize the damage to the trees.
One method of control is to use a pesticide. In small infestations, people often take a bucket of soapy water and remove the inchworms by hand. This can be effective in a small home garden. If you have large trees with inchworms, you can wrap the trunk in sticky bands that prevent the moth from climbing the tree to lay eggs.
Farmers often need to control the inchworm population, and they use a pathogen called Bacillus thuringiensis. The addition of natural predators such as worms or wasps can also help to control them. You can attract birds to your garden with a birdbath, bird food, and a birdhouse.
Inchworms are fascinating little caterpillars but they can be very destructive to trees and other plants. They feed day and night and they can reduce the plant’s ability to perform photosynthesis, which is essential to its survival.
When you have an infestation of these critters, it may be necessary to take steps to control the population before they destroy your plants, flowers, and bushes.