Regional Gardening Reports :: National Gardening Association

In the Garden:
Southern California Coastal & Inland Valleys
July, 2009
Regional Report

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The Good Insects and the Bad Insects

Beneficial Insects: The Good Guys
Welcoming and providing for 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 leave to find their meals elsewhere. Some adult populations--such as the ladybug--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. On the other hand, if you provide them with their preferred forage areas, they will remain in the area to benefit you during later pest scourges. Also, sprinkle the aphid-laden plants, and release the ladybugs at night, and they%ll wake up to %breakfast% and maybe stay until they%ve %finished%!
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 cater%pillars, potato bugs, grass%hoppers, and cut%worms. Treat this group with filtered sprays of pungent concoctions made of ground-up parts of aromatic plants such as mari%gold, 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 suck plant parts. These include aphids, thrips, flies, and scale. Treat this group with sprays of a biodegrad%able insecticidal soap or oil solutions that asphyx%iate the pests by coat%ing them and clogging their respiration 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 (its %points% have been rounded, so 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 month, we%ll move on to specific pests.

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