Synanthedon myopaeformis

Each female can lay up to 250 eggs. Eggs are laid singly on the bark of host trees, typically in cracks or damaged areas of the trunk and branches.[5][7]

Figs.1 larva before last moult, 1a larva after last moult 1b pupa, 1c, 1d pieces of apple bark ravaged by the larva

After hatching, larvae bore into the bark of the host trees, digging into the phloem of the tree. As they bore through the tree, they leave trails of waste that are visible from the outside of the tree. Larvae mature on the host tree for two years.[7][5] During warm weather, the caterpillars move along the bark of the tree feeding on young plant tissues, including the buds of apple trees. At the beginning of winter, the caterpillars once again bore into the tree to spend the cold season under the bark. They emerge in early spring to feed. Larvae repeat this feeding – wintering cycle once more before emerging and boring a final hole in the bark in which to pupate.[7]

After burrowing into the bark, larvae compose golden brown cocoons which stick out from the tree. Compared to the larval stage, the pupal stage is much shorter at two weeks.[5]

Adults emerge from their cocoons in early summer.[5]

After emergence in early summer, adults are active in flight from May through August. Because Synanthedon myopaeformis thrives in warm weather, flight activity is temperature dependent. The adults are significantly less active on cold days compared to warm days. Flight activity ceases at the end of summer when average temperature drops to 15-16 °C.[7]

In 2014, Judd and Eby found that S. myopaeformis does not discriminate between yellow, green and white or between purple, blue, red, and black. The moths also display different behaviors toward traps reflecting green (500-550 nm) and ultraviolet (300-400 nm) light.[3] A second study by Eby in 2012 showed that the moths are sensitive to the same wavelengths of light shown in the previously mentioned study, suggesting that the S. myopaeformis could have dichromatic vision.[11]

Males of the species respond to sex pheromones released by the glands of females. A 2010 study from Judd, Gries, Aurelian, and Gries found that 3,13-octadecadienyl acetate is the primary sex hormone used by S. myopaeformis females. This chemical alone is enough to attract males, although the females do also produce secondary sex hormones in addition to 3,13-octadecadienyl acetate, these appear to play a minor role.[15]

On a bud

Native to Europe, Asia, and northern Africa, but recently released in Canada and the United States, S. myopaeformis has been recognized as a significant threat to apple trees in these regions.[2] Because the larvae bore holes and tunnels under and through the bark of their host trees, the presence of the species is harmful to the health and production of these trees.[16] Previously, damage caused by S. myopaeformis was associated primarily with old, damaged, or otherwise sick apple trees because the lack of integrity of their bark allows the larvae easier access to the inner layers of the trunk and branches.[4][7] However, their potential to harm even previously healthy apple trees is now recognized.[5][2] Because of this, many methods have been tested for controlling the proliferation of the moth.

One method of reproduction control involves the release of the S. myopaeformis sex pheromone into orchards infested by the species. The technique, mating disruption, leads to a dampened male response to female sex hormones, disrupting the mating process. As a result of the overabundance of pheromones, the percentage of mated females decreases relative to unmated females.[17]

Many research studies have used pheromone traps to monitor the population of S. myopaformis. The traps enable monitoring of infestations even when the population is low, and so are an effective reference to determine the best time to apply pest-controlling measures or plant growth regulators.[18]

Other methods of control focus on luring and trapping adults. A Hungarian study found that both male and female red-belted clearwings are attracted to a combination of pear ester and acetic acid. Because many pheromone-based traps attract more males than females, this method is suggested as female-targeted trapping.[19]

Each of the species mentioned above in the “Enemies” section have been used to control populations. These include nematodes,[13] fungi,[14] and bacteria.[1]

Diverse materials have been used to coat the bark of apple trees in an attempt to kill S. myopaeformis eggs and larvae. In 2010, the effectiveness of cotton seed oil, lime, and motor oil were tested in decreasing the number of adults and pupae. All three materials reduced the number of adult moths during the second year, but the oils showed the greatest effect.[2]