Melon Aphid
Aphis gossypii Glover, Aphididae, HEMIPTERA


DESCRIPTION

Adult - This soft-bodied, pear-shaped insect is pale to dark green in cool seasons and yellow in hot, dry summers. Though winged forms develop periodically, most adults are wingless and about 2 mm long. All forms have a pair of tailpipe-like appendages known as cornicles.

Egg - The egg stage does not occur in North Carolina.

Nymph - The nymph is smaller than but similar in shape and color to the wingless adult.


BIOLOGY

Distribution - The melon aphid is distributed throughout the temperate, subtropic, and tropic zones of the world. It occurs in all areas of North Carolina.

Host Plants - A wide range of field and ornamental as well as vegetable crops may be infested by this pest. Some vegetable hosts include asparagus, bean, beet, cowpea, cucurbits, eggplant, okra, spinach, and tomato. Among cucurbits, cucumber and melon are most likely to be infested, followed by squash and pumpkin.

Damage - Damage usually becomes obvious on cucurbits after the vines begin to run. If weather is cool during spring, populations of natural enemies will be slow in building and heavy aphid infestations may result. Congregating on lower leaf surfaces and terminal buds, aphids pierce plants with their needle-like mouthparts and extract sap. When this occurs, leaves curl downward and pucker. Wilting and discoloration follow. Aphid damage weakens plants and may reduce fruit quality and quantity. Honeydew secreted by aphids makes plants sticky and enhances development of black sooty mold on plant foliage.

Life History - In North Carolina, melon aphids spend part of the winter on weed hosts and in gardens on cold tolerant plants such as spinach. During warm periods, they continue feeding until cold weather inactivates them. In spring, winged females fly to suitable host plants and give birth to living young. Each female produces an average of 84 nymphs. Under favorable conditions, a nymph will mature in about 5 days and begin producing its own progeny. Most nymphs develop into wingless adults. However, when crowding occurs or food becomes scarce, winged adults develop and fly to new host plants. Reproduction continues through the winter as in the summer but at a much slower rate. Many overlapping generations are produced each year.


CONTROL

Predators such as lady beetles and their larvae, syrphid fly larvae, and aphid lion larvae reduce melon aphid populations. A small parasitic wasp is also an important natural control agent. In addition, damp weather promotes a fungus disease and hard, driving rains tend to kill large numbers of aphids.

Aphids can be controlled by cultural practices that keep insects in check and by insecticide applications. Planting in a well-prepared, fertile seedbed helps produce a vigorous crop better able to withstand aphid attack. Such a seedbed should not be located near an aphid-infested crop or on land from which an aphid-infested crop has recently been removed.

Insecticides should be applied when it becomes evident that natural and cultural controls are not keeping aphids in check. For up-to-date recommendations and rates, consult the current North Carolina Agricultural Chemicals Manual.

Return to AG-295 Table of Contents