Last modified: Aug. 29, 2019, 8 p.m.
Lyonetia prunifoliella is a very rare and local species in Belgium, mainly occurring in the provinces of Namur and Luxembourg. In 2014 it was discovered in the province of Limburg as new to Flanders and has since also been found in additional provinces.
The first confirmed Belgian record was on 01 June 1997 at Lessive.
The mine starts as a narrow gallery that is almost completely filled with red-brown frass. Later on, this gallery ends abruptly in a blotch in which the grainy black frass is distributed.
See also bladmineerders.be
The cocoon with the pupa hangs at the underside of a leaf in a peculiar hammock, suspended from silken 'guy ropes'.
The eggs are deposited in the underside of a leaf. The young larva initially mines a narrow gallery that is almost completely filled with red-brown frass. Later on, this gallery suddenly ends into a blotch in which the grainy black frass is distributed and is often located against the leaf margin. Nevertheless, part of the frass is worked out by the caterpillar that makes, for this purpose, one or more holes in the lower epidermis. A part of that expelled frass remains hanging in the silken fibres spun by the caterpillar at the bottom of the leaf.
The caterpillar only mines in young leaves of the food plant and can leave its mine and start another one, sometimes even on a different leaf.
Pupation takes place in a peculiar silken hammock, constructed by the caterpillar.
The adults are on the wing from May till the beginning of July and then again from August to September.
The larva lives at the leaf undersides of mainly Prunus spinosa but also other Rosaceae such as e.g. Crataegus, Malus, Cotoneaster, Sorbus, Cydonia, Chaenomeles and Mespilus are accepted as hostplant.
Only occasionally it had been found on Betula.