Most recently reviewed by: Pat Porter (2018)
Common Name(s): Blackmargined Aphid
Pest LocationVegetable and Fruit
There are three species of foliage feeding aphids on pecan: the blackmargined aphid, Monellia caryella; yellow pecan aphid, Monelliopsis pecanis and black pecan aphid, Melanocallis caryaefoliae. Of these three, the blackmargined and yellow pecan aphid are also referred to a yellow aphids or honeydew aphids.
The winged adult blackmargined aphid can be identified by the wings being held in a horizontal position and by the black margins along the wing, Figure 1. The yellow pecan aphid, has clear wings which are held roof-like over the back of the body.
Habitat & Hosts
Blackmargined aphids can be found on pecan, Carya illinoensis (both improved cultivars and native trees) across the pecan belt. They are also found on water hickory, Carya aquatica.
Blackmargined pecan aphids overwinter as eggs under the bark of trees. Nymphs emerge during the spring and feed primarily on the underside of the leaf on the primary and secondary leaf veins, Figure 2. During the summer, many generations of aphids are produced by unmated females giving birth to live female aphids. The time period from birth to adult is approximately 6 days and there can be 16 to 32 generations per year. All aphids during the growing season are females which give birth to live young. Males are not produced until the fall. Mature males mate with females and the females lay the overwintering eggs.
Both adults and nymphs feed on plant sap and excrete a sticky substance referred to as honeydew, Figure 3. A black sooty mold will grow in the honeydew which, if heavy enough, will reduce the photosynthetic ability of the foliage, Figure 4.
ManagementIf you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.
Primary management of blackmargined aphids is with insecticides. Management options with insecticides include the use of several active ingredients that are selective for aphids as well as other insects that feed on plant sap.
Other suggestions for aphid management include only treating problem varieties (if practical), treating only when insect densities exceed the treatment threshold of an average of 25 aphids per compound leaf, and rotating insecticides with different modes of action.
Other management options can include planting winter legume cover crops to generate populations of beneficial predatory insects such as lady beetles and lacewings during the spring. Also, using insecticides selective for Lepidoptera pests when treating for early season insects such as the pecan nut casebearer can help conserve existing populations of beneficial insects.
Two of the main beneficial insect groups which prey on pecan aphids are lacewing larvae (Figure 5) and lady beetle adults and larvae (Figures 6 and 7). Pecan aphids are also parasitized by a small wasp, Aphelinus perpallidus. Parasitized aphids turn black (Figure 8) and should not be mistaken for the black pecan aphid.