Beneficial nematodes are small roundworms that live in the soil. They are typically not visible to the naked eye, and appear white or clear when viewed with a microscope. This particular variety of nematode is a known organic method for controlling damaging insects in home lawns and gardens.
These tiny creatures aid gardeners and homeowners alike by eating crickets, fleas, lawn grubs, and Japanese beetles, among other pests. They function as a parasite that enters the body of a host insect, and infects it with a bacteria. The nematodes live with this particular bacteria in a symbiotic relationship, as the bacteria is incapable of entering hosts without the assistance of the worm.
This bacteria spreads throughout the body of the host, and overwhelms the insect's natural defenses to essentially liquefy its insides. The infected insect will typically die within 48 hours of initial entry by the nematode. The worm then feeds on the excess bacteria and jellied carcass of the pest. The nematodes typically mate during this time period — or self-fertilize, depending on the type of worms involved — and reproduce before leaving to move on to another target.
Beneficial nematodes represent one of 20,000 different types of microscopic worm. Certain varieties of nematode are harmful to both plants and animals. Damaging nematodes usually use a sharp stylet to puncture the cell walls of a plant and feed on the nutrients found there. They are often found in sandy soils and artificially-created turf, like the kind generally used on golf courses and sports fields.
Many varieties of beneficial nematodes may be purchased, in refrigerated packets, online from organic gardening sites or at organic gardening centers. One handful of dirt will typically contain thousands of these creatures. The worms are sold by the millions and may range in price from $20 US Dollars (USD) to $150 USD. Steinernema and heterohabditis are two commonly sold strains of the insect-fighting variety.
To determine how many beneficial nematodes to purchase, measure the size of the area where they will be placed. Typically, one million nematodes will control the usual damaging insect population of 2,000 square feet (around 185 square meters). They may be applied by placing them in water and spraying them onto the affected lawn or garden. These creatures prefer to live in moist soil, but can survive in dry conditions. Ground temperatures should average above 52°F (11°C) when introducing nematodes to a new environment.