![]() ![]() Warm weather in late March and early April will allow the stem mothers to mature quickly and producing more aphids. The warmer it is, the faster each individual aphid will molt and reach maturity. With such a dynamic process, it is difficult to predict what damage will occur. The weather affects both the twig aphid, tree growth, and how quickly predators come in. However, even a few eggs can develop into a large population by bud break if the weather is right. If there are lots of eggs, it is almost guaranteed that there will be enough aphids to cause a problem. The overwintering egg population is the starting point. Once the shoot opens up and the needles lay flat on either side, aphids will still feed, but they don't cause needle curl. The years when we have the most twig aphid damage are typically ones with long, cool springs where the new growth on trees remains at the most vulnerable stage the longest. ![]() How badly the tree is damaged depends on how many aphids are feeding on it when the shoots are expanding. While the BTA is completing its lifecycle, the tree is breaking bud and growing. Twig Aphid Dynamics Skip to Twig Aphid Dynamics Apparently, the natural cues that urge the aphids to produce eggs and end their lifecycle are not found under these greenhouse conditions. Seedling growers should scout seedlings periodically for presence of the aphids. In rare cases, twig aphids have been found on Fraser fir seedlings in greenhouses which have continued to feed and reproduce late into the summer. All twig aphids have died off by the end of June.Īphids in the Greenhouse. Eggs are first found at the end of May and June in western North Carolina. Following mating, the females lay one or two overwintering eggs. ![]() This is the only time males are produced in the lifecycle any given year. The young that the winged form produces also go through three molts to become an adult. The winged stage is found in May and June in western North Carolina.Ĭompleting the Life Cycle. They are only strong enough to lift the aphid away from the tree for the wind to blow it to another location. Though this stage has wings, they are not as useful to the aphid as the wings of a fly or bee. These are also all female and also have live young. However, at some point the stem mother's offspring will be different, having wings at maturity. At maturity some of them will be like the stem mother, allowing a further build-up of the population. The young aphids that the stem mother produces also go through three molts. The adult stem mother and her offspring are easy to find, often feeding on the buds as they start to break. Usually this occurs just prior to or just as the buds start to grow. This allows a quick buildup of the population. Each stem mother can produce as many as 70 live young. These stem mothers produce live aphids which are all clones, genetically identical to the mother. Each aphid molts three times, becoming a little larger with each successive molt. The aphids that hatch from the eggs are all female and are called stem mothers. When twig aphids start to hatch and how quickly they develop is dependent on the spring weather which hatch finishing earlier during warmer springs. These eggs begin to hatch in the spring from early March through mid to April. Eggs can be found anywhere on the tree, but are most common on the most curent growth - last year's shoots. The aphid both "oversummers" and overwinters as a small, black, tear-dropped shaped egg with white waxy rods covering it. The final form produces the overwintering egg. The second form is winged and allows the aphid to spread to other areas. The first form, the stem mother, increases aphid numbers. Each adult form is preceded by the smaller immatures which grow and molt to the adult. Each has a role in the lifecycle and each must be produced in succession for the lifecycle to be complete. There are three distinct adult forms that are produced one after another. ![]() The BTA has an unusual lifecycle, different from any of the other pests of Fraser fir. Balsam Twig Aphid Lifecycle Skip to Balsam Twig Aphid Lifecycle ![]()
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