002 Yponomeuta padella (Orchard Ermine)

16.002 Yponomeuta padella (Orchard Ermine)

ws19-22mm; Jul-Aug; blackthorn (Prunus spinosa), hawthorn (Crataegus spp), plum or cherry (Prunus spp); common throughout GB except N.Scotland

Yponomeuta padella §1

ID: Y.padella/cagnagella/malinellus/rorrella are all very similar with 3 or 4 rows of black dots on a white or whitish ground colour and not more than 8 dots in the most dorsal row. There are no absolute genital differences between these species and the differences in forewing pattern do not distinguish the species with absolute certainty. Y.rorrella has a pattern of grey suffusion that leaves the dorsal half and a pre-terminal costal patch white. Y.cagnagella has no grey suffusion of the forewing ground colour, including the terminal cilia, being entirely white. Y.malinellus has contrastingly grey terminal cilia. Y.padella has a variable amount of grey suffusion and the terminal cilia are the same colour as the terminal area of the wing. MBGBI3 suggests (after Povel, 1984) that the number of antennal segments can be used: Y.padella 51-57, Y.mallinellus 50-56, Y.cagnagella 56-65. So individuals with 50 antennal segments should be Y.mallinellus, those with 51-55 could be either Y.padella or Y.mallinellus, with 56 segments it could be all three species, with 57 segments Y.padella or Y.cagnagella and with 58-65 segments Y cagnagella. (I have not tried counting antennal segments yet). There is much mention from various sources of the defoliation caused by the larvae however I can no reference to the daytime feeding habits of the adults. Specimen §1 was found by day feeding on common ragwort (Senecia jacobaea) flowers. Specimen §2 shows a pattern of grey suffusion that might suggest Y.rorrella, but that species shows 6-8 black dots in each of the 2 dorsal rows, while Y.padella/cagnagella/malinellus show 4-7 dots in these rows.

Variation
Dissection
Male genitalia
Female genitalia

§1 Anglesey; 30/07/2007; fw 9.7mm
§2 Foulness, Essex; 18/07/2010; fw 10.1mm
§3 Arnside, Cumbria; 26/07/2013; male; fw 10.6mm
§4 Conwy Mountain, Caernarvonshire; 23/07/2015; male; fw 10.4mm
§5 Cliburn Moss, Cumbria; 03/08/2019; female; fw 9.6mm; to light
§6 Pound Wood, Essex; 11/07/2019; male; fw 8.0mm
§7 Stour Wood, Essex; 11/08/2021; female; fw 9.9mm
§8 Foulness, Essex; 09/07/2022
All images © Chris Lewis