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Aphids are small, soft-bodied insects with pear shaped bodies that suck plant juices from various plants and shade trees. There are many species of aphids, most of which attack specific plants. Boxelder Aphids (Periphyllus negundinis) are one such species of aphids, which attack only Manitoba Maple, or Boxelder. In normal years, these insects are a pest because they secrete copious amounts of honeydew, which coats surfaces with a sticky substance and can tend to leave objects with a sooty appearance. This year, infestations are so severe that many of our Manitoba Maples have been defoliated. Although these trees have lost their leaves, they are not dying. Trees have a natural defense system where if they loose their leaves due to stress or insect damage, they will flush out a new crop of leaves. This aphid will only attack Manitoba Maples however, conditions are favorable for the development of other species of aphid that attack different plants. Aphids have very complex lifecycles. In the spring, overwintering eggs develop into wingless females that are born pregnant, giving birth to up to 10 young aphids every day, usually more pregnant females. In the fall males are produced and the aphids reproduce sexually, laying eggs which overwinter. Control for aphids on outdoor trees is best achieved by washing them off with a strong stream of water, from a hose or pressure washer once or twice per week. Because they reproduce so efficiently, chemicals are not recommended, as multiple treatments would be needed to control the problem and populations can reestablish in as little as 10 days. Another reason why chemical control is discouraged is most chemicals that could be used for aphid control would also affect aphid predators, such as ladybird beetles (ladybugs). Predator populations rise in response to higher numbers of prey. Another factor, which controls aphid populations, is disease. When pest population levels are abnormally high, aphid diseases occur, which lower population numbers. Most of these diseases flourish during cool damp weather. If a homeowner wishes for long term residual chemical control for aphids in their gardens, they should check with their local garden centre. Always follow label directions and check label for plants that may be susceptible to chemical related injury. Homeowners may not apply pesticide to city owned trees without the written consent of the city of Moose Jaw Parks and Recreation Department. For more information, please contact the Parks and Recreation Department. Back to the Top Back to Disease, Weed & Pest Control |