Number One: Aphids
We think of aphids as more pesky than dangerous in the garden but they do untold billions of dollars’ worth of damage to commercial food crops. Learning more about them will help you cope in your own home garden.
Garden enemy
Ant herding black aphids on an iris seed head in fall. A
phids are enemy Number One in the temperate zone garden. If you never have another pest, you
can almost rest assured that aphids will infiltrate no matter what your defences. Understanding them and how they roll is one of the keys to keeping these suck- ers to a minimum. You probably know that they can
reproduce both sexually and asexually, meaning the females, born of over- wintered eggs in cold climates, can produce offspring without the aid of a male in springtime. They just push out little clones of themselves, also female; in some cases the body of the newly emerged nymph is already bear- ing an incipient offspring. Come fall,
18 • Home and Gardener Living
Close up, you can see the cornicles on the rear end of the aphid. This is where the wax is secreted.
triggered by light and temperature, the females will begin to produce sexual nymphs, both male and female, some- times born without eyes or wings but with reproductive organs that allow them to produce eggs that will over- winter in the nooks and crannies of trees and shrubs. It’s not that aphids are that short-
lived – a generation can live for 20 to 24 days. In one season, some species can produce as many as 41 generations. Under ideal conditions, it is estimated that a single cabbage aphid could start a dynasty that will grow to 1,560,000,00 0,000,000,000,000,000 offspring in a single season. Fortunately those perfect conditions seldom occur.
A little help from their friends It is commonly known that some ants
herd and farm aphids for their honey- dew. They stroke the aphid with their antennae to squeeze the syrupy excre- ment from the aphid’s digestive tract. Some ants even have a relationship
with a caterpillar that eats aphids. Rather than attacking the caterpillar though, they carry the caterpillar larvae off to their nests and actually feed them aphids. Why? Because the caterpillar is a highly efficient producer of excreted honeydew itself – saves the ants a lot of energy that would otherwise be spent milking the tiny aphids. And there is no residual cleanup, because when the caterpillars have finished feeding, they
www.localgardener.net
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40