By Whitney Cranshaw, Colorado State University Cooperative Extension entomologist.
More than 400 species of aphids occur in the Rocky Mountain region and new ones frequently are introduced -- such as the damaging honeysuckle witches broom aphid and the Russian wheat aphid.
Probably any aphid you have ever met was female. In some aphid species, males do not exist or at least have never been observed. In other species, males only occur during one of the many generations that occur during the season, late in the year.
Aphids typically hatch the egg within their body, giving birth to an active nymph stage. Newborn aphids literally are born pregnant, with eggs that will result in live births within 10-14 days.
Aphids can produce either winged or wingless adult stages, a situation controlled by hormones. They will tend to produce more winged stages when environmental conditions are less than optimal - such as when the quality of the plant declines, they become overcrowded or changes in the day length tells them to leave the plant for another host.
Aphids feed on plant sap. Because this material has a relatively high proportion of water and sugars in relation to other nutrients, most of it is excreted as small droplets in the form of sticky "honeydew, that becomes an irritant when it drops from trees onto your parked car."
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010