Melon or Cotton Aphid, Aphis gossypiiHost: A very wide range of field and ornamental as well as vegetable crops may be infested by this pest. Some vegetable hosts include asparagus, beans, beet, cowpeas, cucurbits, eggplant, okra, spinach, and tomato. Among cucurbits, cucumber and watermelon are most likely to be infested, followed by squash and pumpkin.
Symptoms: Damage usually becomes obvious on cucurbits after the vines begin to run. If weather is cool during the 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 needlelike mouthparts and extract sap. When this occurs, leaves curl downward and pucker. Wilting and discoloration follow the loss of plant juices. 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 Cycle: Melon aphids spend part of the winter on weed hosts and in gardens on cold tolerant plants. 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 female 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. This aphid is also a pest of many plants in greenhouses where it breeds continuously. Many overlapping generation are produced each year.
Description: 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 1/16 inch long. All forms have a pair of tailpipe-like appendages known as cornicles. The nymphs are smaller than, but similar in shape and color, to the wingless adults.
Control: Please contact your local county extension office for current information.
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