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A Guide for Buying & Using Beneficial Insects
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BENEFICIAL INSECTS Getting Started Ladybugs Lacewings Fly Parasites Trichogramma Praying Mantis Predatory Mites Whitefly Parasites Mealybug Destroyer Beneficial Nematodes  This site is brought to you by www.PlanetNatural.com |
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 Beneficial Insects in Your BackyardBy Barbara Murphy, University of Maine Cooperative Extension Using insects to control insect pests is becoming more popular as home gardeners look for ways to protect the environment. This is an idea whose time has come. However, to be successful, you'll need to follow some guidelines. Predators and Parasites To begin with, there are basically two categories of insects used as beneficials - predators and parasites. Both can do a tremendous job of controlling pests in your garden. Predators are organisms that kill and feed on their prey outright. They are generally larger than their prey and must eat lots of prey to complete their development. Parasites, on the other hand, are usually smaller and often weaker than their prey. They lay eggs on or within a host insect. The immature larvae use the host for food over time. A parasite will use only one or a few insects for food. Encourage or Import? There are two ways to get beneficial insects into your garden: luring them there naturally or introducing purchased ones. If you are unable to attract beneficial insects into your yard, or you are dealing with a specific pest or you are gardening in an enclosed area such as a greenhouse, the answer may be purchasing and releasing some beneficials. If you introduce beneficials into your yard to control a pest problem, you may find a negative impact on butterflies, moths and other beneficials. This is because some beneficials are general feeders. They don't limit themselves to the pest in question. The more specific you can be with your selection of beneficials, the greater diversity of insects in your yard. Tips to Maintain Beneficial Insects • Don't use chemicals. If you must apply pesticides, stick with less toxic ones such as Bacillus thuringiensis (Bt), neem, horticultural oil and insecticidal soap. • Provide water. A simple dish or pan filled with pebbles will provide drinking water for a variety of insects. • Provide shelter. Leaving some leaf litter and debris under shrubs may provide beneficial insects a place to hide during adverse conditions such as hot summer days. • Increase the diversity of your landscape. Grow a variety of plants to support a variety of insects. Don't be overly concerned with neatness, either. • Do not use zapper lights that electrocute insects. These lights may kill more beneficial insects than pests. • Be ready for spring. The appetites of beneficials may peak before your garden does. Try to have an early bloomer, such as sweet alyssum or pansy, ready so the beneficial parasites can feed on nectar and pollen. • Choose their favorite plants. As a general rule, beneficial insects like tiny flowers that offer both pollen and nectar. Beneficial Insects Available by Mail Ladybird Beetles (Ladybugs and Lady Beetles) Description: Ladybugs, as they are usually called, are voracious predators. Ladybugs prefer to dine on aphids. They are considered an aphid predator. However, as with most beetles, ladybugs are very opportunistic and will eat pests other than aphids, such as mites and insect eggs. Life-cycle: The adult female beetles lay orange, football-shaped eggs usually on the upper-sides of leaves of infested plants - up to 50 of them per day. The eggs hatch into larvae with black or blue alligator-like markings of orange. These, too, are fierce predators, consuming 400 or so aphids during this stage of life. The life-span of these predators is roughly 28 days in their immature stages, then around 11 months as adults. The conditions for optimum performance will be between 66 to 88 degrees F., with a relative humidity of 40 percent or greater. Advisories: First and foremost, they're flighty. If not released properly, ladybugs can disperse completely within 24 hours. Even when they are released properly, 90 to 95 percent will bolt anyway. It is expected; it is in their nature. It is the five to 10 percent that stick around that do the job. Aside from watering the site in the evening before releasing, having plenty of flowering, pollen-producing plants in the landscape is a big plus. Green Lacewings Description: You can purchase these predators as eggs, larvae and adults. The eggs are useful when you're in no great hurry to get rid of the pests. The larvae are useful for a quick cleanup. The adults, being nomadic, are useful in tree applications. The larvae are the only predatory form of this insect. Lacewing larvae can tackle a great number of aphid species, as well as other soft-bodied pests such as immature scale insects, mealybugs, whiteflies and other insect eggs. The larvae are very cannibalistic and are separated in transit by a frame comprised of little compartments, which can be opened a row at a time for predator release. The adults come in a tube screened at both ends. Oftentimes, they are already laying eggs inside the tube. The eggs are shipped loose in an inert medium that is used to insure proper placement of the eggs. Life-cycle: The life-span of these predators is roughly 30 days in their immature stages, and about two months as adults. The predaceous larval stage lasts roughly 15 to 20 days. The conditions for optimum performance will be between 67 to 89 degrees F., with a relative humidity of 30 percent or greater. Pollen, nectar and even honeydew will help sustain the adults. They are not predaceous but do need food. Advisories: If present, controlling ants is recommended. They will eat lacewing eggs and defend aphids from predators to protect their honeydew food. Trichogramma Wasps Description: These tiny wasps are very popular and very effective Lepidopteran egg parasitoids. Lepidoptera is the name of the order to which moths and butterflies belong. There are two common species of this wasp used for caterpillar control. Trichogramma minutum is the insect of choice for an orchard or tall crop setting. (In this case, "tall crop" means one which is over eight feet.) Trichogramma pretiosum is the best species to use in a field, green-house or short crop setting. (In this case, "short crop" means one which is under eight feet.) Both are shipped ready-to-hatch from grain moth eggs. Some popular hosts of trichogramma wasps include the eggs of the: gypsy moth, codling moth, tomato hornworm, cabbage looper, imported cabbage worm and European corn borer. Life-cycle: The wasps work by laying eggs in the eggs of many Lepidopteran species. The adult wasps can lay up to 300 eggs each, parasitizing 300 of soon-to-be destructive caterpillars. Instead of pests hatching out, more tiny wasps hatch out from the pests' eggs. The life span of these parasitoids is roughly seven days in their immature stages, then up to 10 days as adults. With such a short life-cycle, you can see several generations per year in Maine. Advisories: Trichogramma wasps have a wide host range. This means they can parasitize a great number of eggs belonging to a great number of species. They are indiscriminate parasites and can be hazardous to non-target Lepidoptera. You must know the pest with which you're dealing. Timing is critical in many cases. Prey eggs have to be available since the wasps can't parasitize the larvae. |
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