By Don Trotter
Beneficial Insects, Voracious Yet Fragile Friends
Hello fellow Earthlings, and welcome to the fascinating world of beneficial insects in the garden. This month we will be discussing these incredible creatures and the good they do in controlling pest insect populations. So let's take a stroll through the insectary and discuss some of the more popular species of beneficial insects that can normally be found at better garden centers around the area or by mail order.
These are probably the most widely recognized of all beneficial organisms besides earthworms. "Ladybugs", as they are often called, are predators of several different types of pest insects. Ladybugs feed on several species of aphids, mealybugs, spider mites, soft scales, and certain whitefly species. However, these insects are migratory, and if you don't give them something interesting to keep their attention, they will leave.
Ladybugs can be purchased at many home centers and nurseries during the warmer part of the year. Ladybugs are considered "beneficial generalists" because they have a varied appetite for the critters that bug your garden. Releasing of adult ladybugs should be done in the evening in moist conditions, or on a cool day. Lower temperatures lower their activity, so in cooler temperatures they will be less likely to fly away as soon as you release them.
Green lacewings or just lacewings are also considered beneficial generalist insects. However the main difference from lacewing and ladybugs feeding habits are that adult lace-wings are not predatory, ladybugs are. The larvae of the green lacewing are voracious predators of aphids, mealybugs, spider mites, soft scales, most whitefly species, caterpillar eggs, and they will sometimes eat snail and slug eggs as well as each other if there are no other pests to munch out on. The larva of the green lacewing are called "Aphid lions", this does not begin to describe how hungry these good guys are or how effective they are as a biological control for pests in the garden.
Many garden centers carry green lacewings either in stock or as a mail away package direct to the insectaries where they are grown. This type of purchasing green lacewings ensures that you receive fresh insects directly to your mailbox. The adult lacewing is a slender green or brown flying insect with large transparent wings and a kind of fluttering flight that once recognized you will see them everywhere. The adults feed mostly on pollen and nectar from flowers around the garden. Luring native lacewings to your garden is a very good reason to find some room in the garden for "companion plantings" that produce the type of flowers that are pollen and nectar rich.
These black beetles with red heads are directly related to ladybugs. Cryptolaemus beetles are also known by their common name "Mealybug destroyers", this is the truth! Both adults and the larvae of this beneficial insect feed on mealybugs, some aphids, and soft scales. Cryptolaemus does prefer mealybugs, and are often used for controlling this pest indoors and in other areas where spraying is not possible. The larva looks just like a large mealybug, however the cryp-tolaemus larva is more mobile than a mealybug, and the hairs are curly instead of straight like they are on a mealybug. Cryptolaemus beetles are normally sold direct from the nursery as ladybugs are. They are a little more money than ladybugs, but they're worth it!
Delphastus beetles are another relative of the ladybug that prefer to eat several species of whitefly. There are two main species of the delph-astus beetle fairly common at certain nurseries and garden centers. Del-phastus pusillus is a predator of silverleaf whitefly and some of the other smaller species of whitefly.
Delphastus catalinae is another available species that is normally found in trees (arboreal), they rarely come down close to the ground to eat. These two insects have been inaccurately sold to the public as an effective control for the giant tropical whitefly that seems to plague many of our tropical ornamentals and fruits during the summer. Delphastus will feed on the tropical whitefly, but do not keep up well with runaway populations of this pest, and they have difficulty negotiating the "floss" that the larvae of the tropical whitefly produce to protect themselves.
Delphastus catalinae is often used by commercial avocado and citrus growers to control the tropical whitefly in their trees with good success. Delphastus are normally sold in the same way ladybugs and cryptolaemus are sold, but they can be very expensive depending on the dealer.
Trichogramma wasps are parasites of many species of caterpillars. Don't let the "wasp" part scare you, these beneficial insects are so small that even if they did want to sting you (and they don't) you couldn't feel it. Trichogramma are way too busy laying their eggs inside or on their hosts. These insects are the most widely used beneficial insects used by farmers and growers to control damage that can be caused by hungry caterpillars.
Trichogramma are often sold as parasitized moth eggs on flat pieces of plastic that can be hung close to where caterpillars are damaging plants so the adult wasps do not have to search too far for caterpillar eggs once they emerge from the eggs they came in. Adult trichogramma wasps feed on nectar and pollen. Keeping these beneficial insects in the garden is a good reason to put out some companion plantings of the flowers that they prefer to feed from. Tricho-gramma are also often sold as mail away packages. This ensures the buyer that you get fresh product that have not already emerged from their hosts.
These are just a few of the beneficial insects that are very effective at controlling pest populations in your garden. Many beneficial insect species are very sensitive to pesticides and don't recover well from the spraying of these chemicals. They should be employed as an alternative to spraying of potentially harmful chemical insecticides.
Next time we will continue this discussion covering predatory snails, beneficial nematodes, and a couple of bacteria that work very well at controlling everything from mosquitoes to tomato hornworms. See you in the garden! HAPPY EARTH DAY!!!!
Got questions? Fax the Doc at (760) 632-8175 or e-mail him at Curly@mill.net Don Trotter's columns on natural gardening appear nationally in environmentally sensitive publications. Look for Don's book Natural Gardening A to Z coming in July from Hay House Publishing.
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