One of the dilemmas facing all gardeners is how to manage the bad pests while still encouraging the good ones---how to maintain an ecological balance by limiting the use of pesticides while still controlling damaging insects. With worms, a gardener can do a number of things to encourage beneficial earthworms, while also limiting the number of bad guys, such as cutworms and cabbage worms.
There are close to 3,000 species of these helpful garden worms, with one in South Africa measuring 22 feet long. Gardeners love earthworms because they break down organic matter like leaves and twigs so that flowers and shrubs can more easily absorb the nutrients from the soil. Moreover, they aerate the soil with their underground tunnels, provide nitrogen through their slime and add organic matter to the soil with their discarded casings. Interesting facts about earthworms include the confirmation that yes, it is possible for earthworms to replace segments of their bodies if a gardener accidentally cuts one in half; that baby worms hatch from cocoons smaller than a grain of rice and that worms are hermaphrodites, meaning that they are both male and female simultaneously, producing and fertilizing eggs by themselves.
These velvety green worms with dark stripes down their backs are the larva of butterflies and feed on cabbage and other cool crops like broccoli, collards and kale. They are easy to spot as eggs because they are a yellowish color and appear on the outer leaves. Cabbage worms can do tremendous damage to crops, eating all the leaves and eating into cabbage heads from the base of the plant. Gardeners control them with hand-picking, by introducing predators such as lacewings, a flying bug, or by using a number of different pesticides.
Cutworms are so named because many of them do actually cut down young seedlings at the soil line when feeding. Unfortunately, there are many species of cutworms--some feed at surface levels, others climb vines and stems to do their damage and some stay underneath the soil and damage roots. Many species feed at night and go underground during the day. Most cutworms grow as larvae during the winter months in the ground or in garden debris of grass, leaves and weeds, emerging in spring ravenously hungry. In early summer, they become pupate and later turn into moths. To control cutworms, the Sunset Western Garden Book recommends applications of sulfur, while the University of Rhode Island agronomists also recommend frequent hoeing or cultivation of the soil to disrupt the cutworm habitat, placing foil collars around seedlings, using toads as natural predators and applying chemicals.