Illinois Natural History Survey - University of Illinois

Myzus lythri in North America

This aphid was first found in Colorado in the 1930s. It is of European origin and was probably brought in on one of its host plants. It is presently found throughout much of North America where purple loosestrife and its alternate host, mahaleb cherry are found.

In the photo at left is a wingless adult femaleMyzus lythri on a leaf of purple loosestrife. Over a 2-3 week period this one female may produce more than 50 young. In late summer and early fall large populations of this aphid sometimes develop, covering leaves and flower spikes.

Life cycle of Myzus lythri

To survive from year to year this aphid species needs two very different host plants. It survives the winter as eggs on a European cherry also imported into North America where it has been used extensively as root stock for sour cherries. In the spring the eggs hatch and after two subsequent generations winged aphids develop and leave cherry in search of purple loosestrife. Once they find purple loosestrife the settle on it, begin feeding and reproducing. This continues until the fall when they produce forms that fly back to cherry where overwintering eggs are laid.

As with most species of aphids, without check they have the potential to produce massive numbers of offspring and have many generations each year. The possible use of this species as a biological control agent against purple loosestrife has been investigated. There are major barriers to this, the first is that they seem to be a food source for a surprising number of generalist predators and secondly the complex life cycle where they return to Prunus mahalebfor the production of overwintering eggs. This cherry is rather uncommon so the probablility of the aphids leaving purple loosestrife in the fall and finding one of these particular cherries is not good. What is surprising is that periodically large populations of this aphid have developed and caused considerable stress to local loosestrife populations.

Information on this page maintained by David Voegtlin.

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