There are thousands of different worm species living on the planet today. In fact, there are more than 4,400 species and more than half (2,700) are species of earthworm and 1,200 are species of inchworm. Places like China, Australia, Greenland, and the Sahara Desert have their own indigenous species of earthworms. Besides the Sahara Desert, you won’t find large numbers of worms living in “sandy” areas, especially sandy beaches. The vast majority of worms on our planet can only survive under certain environmental conditions.
Worms need a moist environment for survival, and they must also remain close to their food supply. Worms eat leaves and dead grass, which contain organisms that provide a healthy diet of bacteria, algae, and fungi. Worms feast on dirt as well, especially if they live deeper inside the earth. Worms also eat plants, fruits, and vegetables. The worm’s moist and sustenance rich environment plays an extremely important role in reproduction as well. Worms prefer to mate and reproduce in warm moist soil, away from the light.
Earthworms can be found in just about every corner of the earth. They live in trees, in bark, and under rocks as well as along rivers, near springs, and in ponds. Their favorite place to live, however, is burrowed inside the earth’s rich soil. During the winter months they burrow deep within the earth until the surface warms again during the spring. During the warm summer months, worms stay closer to the tops of soil where they create tunnels to wiggle in and out of. This allows air to get to the plant roots.
Without the worm’s tunneling action, called “aeration,” the earth’s trees, plants, fruits, and vegetables would not survive. In addition to aerating the soil, which keeps plants alive, worms also eat organic matter, digest it, and excrete the digested material. Worms eat so much that they typically produce digested material equal to their own weight every 24 hours. This digested material is called castings. The castings are rich with much needed phosphorus, calcium, and potassium.
Earthworms belong to one of several different types of ecological groups. There are three broad ecological groups that have been identified for earthworms including epigeic, endogeic, and anecic. The groups are based on what the earthworms eat and where they tend to live in the soil. The epigeic group is a litter feeder and dweller, pigmented, small in size, and it doesn’t burrow. The endogeic group consists of rich soil feeders, topsoil dwellers, has no pigmentation, burrows horizontally, and it is small in size. The anecic consists of litter and soil feeders, soil dwellers, dorsally pigmented bodies, extensive vertical burrows, and a large size. Size and color are usually good distinguishers for adult earthworms.
The clitellum of adult earthworms contains features called genital tumescence, and tubercula pubertatis. The clitellum features, the male pores, and female pores are found above the clitellum and are all parts of the earthworm reproductive system. The earthworm has “setae” which are tiny hair-like projections that are arranged in rows along the earthworm body. The setae are used for locomotion by the earthworm.
Worms have no lungs, so they breathe through their skin. This means that the worm’s environment and skin must be moist at all times. This allows the worm to breathe in oxygen. If the worm’s skin dries out, the worm will die from suffocation. While worms need moisture to survive, too much moisture can be fatal. If too much water is present, it takes the place of oxygen, which will cause the worms to flee to the surface. Once on the surface, worms will be exposed to sunlight. If worms remain in the sunlight for too long, they can become paralyzed.
Although you cannot see them, believe it or not, worms do have mouths. The earthworm mouth is called the prostomium. The worm’s mouth is actually big enough and powerful enough to grab a leaf and drag it around. They also have a pharynx, esophagus, crop, gizzard and intestine. When the worm eats its food, it pulls the materials into its mouth with the help of the pharynx and its prostomium (also called acron). This creates a suction motion. This suction motion aids in helping the worm consume large amounts of food in a sort amount of time. The gizzard grinds the food.
An inchworm is the larvae of moths, of the family Geometridae (phylum Arthropoda, class Insecta, order Lepidoptera). This large, widely diffused group has more than 1,200 species indigenous to North America. Some inchworms (also “inch worm”) are considered average while others are considered extraordinary. Inch worms do, however, have many common characteristics. They have smooth, hairless bodies, and they typically grow up to one inch in length. Their colors run the gamut from brown and black to bright green.
Also referred to as loopers, measuring worms, and spanworms, inchworms have three pairs of legs at the front end and two to three pairs of prolegs or larval abdominal appendages at the rear. Inchworms travel by drawing their hind end forward while gripping the earth with its prolegs. They have the ability to stand erect and motionless when poked or prodded in any way.
Much like spiders, some inch worms have the ability produce thin delicate lines. In some cases, these thin lines are made of silk. It just so happens that one of the most destructive types of inchworms, called cankerworms, produces soft silk threads as they drop from trees to evade predators. Also called measuring worms, cankerworms vary in color, but their bodies consist of long horizontal stripes. Cankerworms feed on shrub foliage and tree foliage. These creatures like to hang out in apples, elms, oaks, lindens, sweetgums, and a wide variety of other shade and fruit trees.
Another type of inch worm, also called Looper and Cabbage Looper, overwinters as green to brown pupae tightly wrapped in cocoons (not webs) of white thread. In the spring, the adult moth emerges. The adult lays its eggs, typically on the surface of leaves. Once the larvae emerge, they feed for two to four weeks. Once they’ve had their fill, the larvae spin cocoons similar to the ones used during the overwinter process. The larvae prefer vegetable gardens and they eat a variety of crops including: celery, cabbage, cauliflower, radishes, Brussels sprouts, beans, parsley, broccoli, potatoes, tomatoes, and peas.
Unfortunately, larvae eating habits cause massive destruction to food crop foliage. Simply put, larvae will eat as many holes as they can in the leaves of all kinds. Fortunately, there are several ways to control larvae/inchworm infestations. Trichogramma wasps are natural predators as well as birds, yellow jackets and paper wasps. They are also controlled by natural diseases and parasites. Wilt disease causes the worms body to rot. This usually happens late in the season. “Bacillus thuringiensis,” a wilt pathogen, is available to gardeners to help control infestations.