Do you know of a source for acquiring Encarsia formosa wasps? We
are getting questions about the Giant Whitefly on the Orange County
hotline.
In My Garden Blog
Southern California Coastal & Inland Valleys
July 16, 2009
By
Yvonne Savio,
Pasadena, CA
Ladybugs love aphids!
The Good Insects and the Bad Insects
Welcoming and providing for beneficial insect predators in your garden is a wise move. There are limitations to the value of purchasing adult predators, however. Once they've eaten their fill soon after release in your garden, they'll often leave to find their meals elsewhere. Some adult populations -- such as ladybugs -- are "programmed" to automatically fly away from their point of release in order to search for their food. In both cases, they will no longer be around your garden to feed on subsequent populations of pests. In other words, you paid for them to eat but one meal from your garden. To maximize the likelihood that they'll stick around, sprinkle the purchased ladybugs on aphid-laden plants at night, so they'll wake up to "breakfast" and maybe stay until they've "finished!"
On the other hand, if you provide native beneficials with their preferred forage areas, they will be more likely to remain in the area to benefit you during later pest scourges.
Some of the predators more commonly used are:
Predator (eater): Object (eatee)
Aphytis wasp: Scale
Cryptolaemus: Mealybugs
Encarsia formosa: Whiteflies
Fly parasites: Flies
Lacewing: Ants, aphids, some worms and caterpillars, and eggs and larvae of other pests.
Ladybug: Aphid, mite
Praying mantis: Wide variety (including their own mates!)
Predatory mites: Other mites
Trichogramma wasp : Variety of worms & caterpillars
Another helpful predator is the daddy-long-legs, which constantly "combs" plants for aphids and larvae of other insects.
Pests: The Bad Guys
Garden pests can be grouped into either of two major categories: chewers and suckers.
The chewers. They bite to get what they want and include caterpillars, potato bugs, grasshoppers, and cutworms. Treat this group with filtered sprays of pungent concoctions made of ground-up parts of aromatic plants such as marigold, garlic, onion, or hot pepper. Many of these insects can be eradicated with two sprayings of a tabasco-detergent-alcohol spray. Combine one tablespoon liquid dishwashing detergent, one tablespoon of tabasco sauce, one quart of rubbing alcohol, and one gallon of water. Be careful to wear non-absorbant rubber gloves and to not breathe the fumes, as the tabasco liquid and vapor are very irritating. (This is why they're so effective on the pests!)
The suckers. These piece plant parts and suck out the sap. These include aphids, thrips, flies, and scale. Treat this group with sprays of a biodegradable insecticidal soap or oil solutions that asphyxiate the pests by coating them and clogging their respiratory systems.
Two General Approaches
Here are two general approaches to utilize in your garden.
Diatomaceous earth. When magnified, it looks like a cluster of pins pointing out of a ball. These "pins" prick the bodies of insects, causing their body fluids to drain out. While fatal to most insects, it has no harmful effect on people or warm-blooded animals. Vegetables can be eaten the same day they're treated. However, be sure to use only the type sold specifically for the garden, not the one to be used in pool filters (the "points" have been rounded, so it is ineffective in pest control).
Aluminum garden siding or boards laid on the soil. Lay down the boards to attract a variety of pests to the cool darkness underneath them. Lift the boards in the morning and early evening, destroy the pests, and replace the boards for the next "catch."
Next time, we'll move on to specific pests.
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We welcome your questions and comments about this column. If you have gardening questions unrelated to the column, please ask them on our message boards.
Mary Steele
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Yvonne Savio
Hi, Mary --
Check with:
1. Our University of California Cooperative Extension Los Angeles
County Master Gardener Helplines -- phone 323-260-3238 or email
mglosangeleshelpline@ucdavis.edu
2. Our University of California Integrated Pest Management,
www.ipm.ucdavis.edu
3. Peaceful Valley Farm Supply, www.groworganic.com