Key Features
- Sticky liquid (honeydew)
- Black sooty mold on leaves and stems
- Small, pear-shape, tubes on abdomen
Symptoms
Aphids can curl leaves, distort plant growth or even kill plants. They produce a sticky liquid excrement called honeydew that is deposited on leaves and branches. This secretion sticks leaves together or turn leaves black when colonized by a fungus called sooty mold. Some aphids just excrete honeydew and others excrete honeydew and wax. Deposition of honeydew is more of a nuisance over cars and highly trafficked areas because of its ability to attract stinging wasps. Aphids are generally pear shaped insects, with two visible bumps on the hind end. Most species have winged and wingless forms. When present, wings are clear and held roof-like over their body when the insect is at rest.
Biology
Most aphids spend winter, spring and fall on trees, shrubs and other woody plants. In the spring when sap rises in trees and green buds sprout from twigs, aphids are already near the young leaf or stem tissue to feed on the sap. Aphids will continue to feed and reproduce wingless offspring without mating for a few weeks while plants are actively producing new twigs and leaves. As plant growth slows and food becomes exhausted, aphid females produce wingless offspring that fly to more vigorously growing annual and perennial flowers, vegetables and agronomic crops. Aphids damage plants when large numbers are present on plants, coating them with sticky honeydew excrement, or black sooty mold. Although aphids can transmit serious diseases to commercial flower, vegetable, and fruit producers, this is not common in home landscapes.
Management Recommendations
In most cases, aphids are only temporary cosmetic problems in ornamental home landscapes. In time, the native predators and parasites of aphids usually take care of most problems. Control is needed when plants become heavily distorted, or if honeydew production is excessive making plants unsightly, or if the honeydew creates a sticky mess that attracts stinging insects. Keep plants well watered and properly fertilized. Over fertilization can prolong aphid infestation by stimulating shoot growth. Application of neem products containing azadirachtin, insecticidal soaps or summer oils can kill large numbers of aphids while sparing many natural enemies. Neem is systemic and can penetrate tight leaf buds where aphids can feed. Other products labeled for foliar applications can kill aphids, but may foster outbreaks of spider mites later in the season. Soil applied systemic insecticides like clothianidin, imidacloprid (Merit), or dinotefuran (Safari), can be quite effective against early season leaf distorters and requires applications at least 4 weeks before eggs hatch, or perhaps during the previous fall. To protect bees, do not apply foliar insecticides when bees are flying to flowers and avoid using soil insecticides plants prior to or during flower production.
Effective Pesticides
Active Ingredients include: Abamectin, Azadirachtin, Bifenazate, Horticultural oil (Paraffinic or superior oil) , Insecticidal soap (Potassium salt of fatty acid), Neem oil, Pyrethrin, Spiromesefin
Resources
