Home & Garden

Sap-sucking aphids are first in the ‘pest parade’

The first garden pests to make their appearance in the spring are often the group known as “sucking” insects.

First in the parade of “sap suckers” are aphids. Attracted to tender new growth, these pear-shaped, soft-bodied insects are about 1/8” in length. Adults are generally wingless, but produce wings at the end of the growing season, or when populations are high.

The life cycle of aphids is remarkable and explains why they appear quickly in large numbers.

In spring, females (called “stem mothers”) emerge from eggs. They do not need a mate to reproduce. Stem mothers give birth to live daughters, and these offspring give birth to more live daughters, without any “hanky-panky” going on.

At the end of the season, aphids begin to produce both sons and daughters. When these multi-gender colonies mature, they mate and the females lay eggs on bud scales, continuing the cycle the following spring.

Gardeners who practice integrated pest management learn to tolerate the presence of a few aphids. Natural enemies such as lady beetles and their larvae, lacewings and tiny wasps often keep aphid numbers below damaging levels.

Beneficial insects often arrive several days to several weeks after the aphids begin to multiply, so in the lag time, use a strong jet of water from the hose to wash aphids from leaves. Infested portions of the plant can be pinched or pruned off.

Insecticidal soap kills aphids on contact and horticultural oils provide aphid control without leaving toxic residue for natural enemies.

By making your garden an attractive place for beneficial insects, with flowers that bloom over a long period of time, you’ll be taking the first step to limiting aphid infestation.


Contact the University of California Cooperative Extension Master Gardeners: at 781-5939 from 1 to 5 p.m. on Monday and Thursday; at 473-7190 from 10 a.m. to noon on Wednesday in Arroyo Grande; and at 434-4105 from 9 a.m. to noon on Wednesday in Templeton. Visit the UCCE Master Gardeners Web site at http://ucanr.org/sites/mgslo or email mgsanluisobispo@ucdavis.edu  .