The adult form of the Sesia is a butterfly with a wingspan variable from 2 to 2.8 cm with wings almost transparent, with scales and with dark colored edges. The body has a slender shape with black thorax and abdomen and a transversal reddish ocher band placed on the abdomen. The larva, about 1.5-2.3 cm long, tends to yellowish with the head and the first ocher-reddish thoracic segment. Being a xylophagous insect (an animal, that is, that feeds on wood) it attacks plants that are already sick or that have however suffered recent damages, not yet healed. He gladly takes advantage of cancers from Nectria cancers, of the lesions created on the trunk and on the branches from the cold, of those caused by other xylophagi. With this term, which derives from the Greek definition σής which means moth, we refer to the Synanthedon myopaeformis Borkhausen, a moth that strikes above all apple and pear plants.
Characteristics of sesia
We must not forget, however, that this parasite also penetrates into cuts caused by pruning or grafts and even hits the collar area. The larvae dig the tunnels under the bark, generally superficial, but which can also descend to a certain depth. It must be said that since the caterpillar develops only in the presence of decayed trees, the damage caused by this insect is not significant. Certainly the penetration of graft wounds by the insect causes desiccation of the vegetation and the tunnels excavated open the way to other pathogens, such as the Pomace Cancer. But what are the plants that affect this insect in detail? They are: the Rosaceae with shrubs, the Melo, the Pero, the Biancospino, the Sorbo and the Melocotogno.
The Sesia winters in the state of larva, in the tunnels that it has dug into the bark of the trunk or branches. The climate has a strong impact on this insect which, depending on the environment in which it is found, concludes its biological cycle in one or two years; in Northern Italy, for example, it is biennial. The adult specimens flicker in the middle of summer, from May to August and the females lay their eggs. The larvae begin to dig the tunnels where they will spend the winter. At the end of the bad season the larvae can flicker, once they reach adulthood. Or continue their action as larvae, continuing in the excavation of the tunnels, spending another winter in a larva state and then flicking, ending the two-year cycle.
Pest control can be chemical, integrated and biological. Beware of damage from cold and pruning cuts, covering the latter to avoid infiltration of the pathogen. Before carrying out the treatments it is good to carry out an adequate control of the infesting population present, through the use of sexual traps to be used in May. Chemicals can be purchased from an authorized retailer or in garden centers. It should be remembered that some products used against other insects are also active against Sesia. You can also intervene in summer, between mid-June and July. For biological control, entomopathogenic nematodes of the species Steinernema Spp and Heteroshabditis Spp. Can be used.