Yponomeuta padellus L. - Small Ermine Moth, Cherry Ermine Moth
Systematic position.Class Insecta, order Lepidoptera, family Yponomeutidae, genus Yponomeuta. Sibling species Yponomeuta meridionalis Gershenson is described from Varzob Gorge of Tajikistan.
Synonyms.Hyponomeuta padella L., Hyponomeuta variabilis Z.
Biological group.It is an oligophagous pest of mainly stone-fruit crops.
Morphology and biology.Externally moth does not differ significantly from Yponomeuta malinellus adult. Forewings white, with 16-19 black dots, located in three irregular rows (wingspan 18-22 mm). Hind-wings are ash-gray. Caterpillars of the last instar are 14-16 mm in length, dirty-yellow to gray, with black head, wing buds, and spiracle rims, not much different from Y. malinellus. Pupa 7.5-11 mm in length, dark-yellow, with black head, wing buds, and cremaster; the last having 6 setae. Biology of the species is similar to biology of Y. malinellus. Female lays eggs in groups on branches of host plants, covering the eggs with a shield. Caterpillars live openly in colonies. Caterpillars of 1st instar do not mine leaves in contrast to Y. malinellus, instead they plait web nests immediately, fastening leaves in twos. Pupation takes place in nests; white cocoons are located separately, rather than aggregately in compact packs. Cocoons friable, with thin transparent walls; pupa is visible. Caterpillars of 1st instar winter under shield.
Distribution.This species is distributed everywhere in West Europe. In the former USSR it is distributed in the European part (northward to the Leningrad Region), in Transcaucasia, southern Kazakhstan, Central Asia.
Ecology.This is a strictly monovoltine species. Caterpillars emerge from under shields at the end of April. They pupate in the first third of June. Dry and hot weather is favorable for the development of caterpillars. Moths fly from the middle of May until the end of August. Active flight begins right before twilight and lasts until dark. The main entomophages of this species are Ageniaspis fuscicollis Dalm., Elasmus albipennis Thorns., Tetrastichus evonymellae Bche., etc. Infection with a bacterium Bacillus subtilis has also been reported.
Economic significance.Develops on wild and cultural Rosaceae, i.e., on sloe, sweet cherry, cherry, plum, cherry plum, apricot, hawthorn, less often on apple, pear, and mountain ash. It is also found on willow, ash-tree, and oak. This species is very harmful to stone-fruits in steppe and forest-steppe areas. The caterpillar sceletonizes leaves, eating around them. During dry years the trees lose all leaves which results in an almost complete loss of fruits.
Control measures.Agronomical measures: gathering and destruction of falling leaves in summer, removal and burning of web nests with caterpillars and pupae. Biological measures: introduction of the parasite Ageniaspis fuscicollis, application of biological preparations. Chemical measures (if necessary): insecticide treatments early in the spring, before buds blossom and before caterpillars emerge from under shields, and also at the end of flowering, right after the petals fall.
Reference citations:Gershenzon Z.S. 1974a. Family Yponomeutidae. In: Vasil.ev V.P., ed. Pests of agricultural crops and forest plantations. V. 2. Arthropods. Kiev: Urozhai. 245-250 p. (In Russian)
Gershenzon Z.S. 1974b. Yponomeutidae, Argyresthiidae. In: Puchkov V.G., ed. Fauna of Ukraine. V. 15(6). Kiev: Naukova Dumka. 132 p. (in Ukrainian)
Gershenzon Z.S. 1986. List of Yponomeutidae (Lepidoptera) of the USSR fauna. In: Gilyarov M.S., ed. Proceedings VEO. Lepidoptera of the USSR. V. 67. Leningrad: AN SSSR. 10-19 p. (In Russian)
Savkovskii P.P. 1976. Atlas of the pests of fruit and berry plants. Kiev: Urozhai. 207 p. (In Russian)
Sinev S.Yu. 1994. Family Yponomeutidae (Hyponomeutidae). In: Kuznetsov V.I., ed. Insects and mites - pests of agricultural plants. V. 3(1). Lepidoptera. St. Petersburg: Nauka. 247-254 p. (In Russian)
Vasil.ev V.P., Livshits I.Z. 1984. Pests of fruit crops. Moscow: Kolos. 399 p. (In Russian)