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Spring is near for those of us in the Northern Hemisphere. And along with spring comes a plethora of critters which try to take the fun out of gardening. I'm speaking of pest insects and mites, of course!
Aphids
Aphids are divided into two major groups - the chief difference being those that only lay eggs (like the Pine Aphid) and those that bear live young. The Rose Aphid falls into this second group. Biology: In temperate climates, the female lays a fall batch of eggs in nooks and crannies throughout the landscape, near host plants. In the spring, the eggs hatch and become "stem mothers" - that is, they are all female. They also already have their young within their bodies. These stem mothers produce more females, which produce even more females - all without mating. Within a few days, thousands of aphids can be born. In late summer and early fall, the females also produce a few males. Females born at the same time mate, and eggs are laid for next season's offspring. Damage: As a group, aphids attack a plant by sucking its fluids from tender new growth. They are attracted to the concentrated nitrogen in these new growth areas. The results are deformed leaves and new bloom stems. In addition to deforming new growth, aphids cause another problem. Their exudate is a substance called "honeydew" - a sweet, syrup-like material which appears on leaves and stems. It is a food source for many insects, both pest and beneficial. But honeydew causes two more problems: "Sooty mold" and ants. Sooty mold is a fungus which grows in the honeydew. It makes the leaves look dirty and black. Many unknowing gardeners spray a fungicide on the sooty mold, attacking the symptom rather than the cause - the aphid. Honeydew is also a food source for ants. Ants will fiercely defend their honeydew "factories" against all natural predators, like lacewing and lady beetle larvae. They have even been known to move aphids from one plant to another so additional honeydew sources can be created, much like a dairyman moving his cows from one pasture to another.
For a complete listing of article comments, questions, and other discussions related to Mark Whitelaw's Rose Gardening topic, please visit the Discussions page. |
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Description: The Rose Aphid (Macrosiphum rosae) is only one of the 4000-plus species of aphids which vary in size, color, and even mating habits. Aphids are usually restricted in their preference for food - attacking a specific host or a closely related species. Rose Aphids, for example, attack not only the rose, but may attack many of its cousins like the photinia, pyracantha, and many of our fruit trees.
