Zeugophora subspinosa (Fabricius, 1781)

This widespread western Palaearctic species occurs from Spain to northern Italy and the Caucasus in the south, extends north to the Arctic Circle in Scandinavia and east to western Siberia, and is the most common member of the genus across most of this range. In the UK it is locally common in south and central England becoming rarer further north and generally absent from the West Country, Wales and Scotland although there are a few records from the northeast highlands. Adults occur year-round and are active from April until September or October in a range of habitats where the host, Populus tremula (aspen), occurs; woodland, parkland, river margins and fenland etc. In the UK they seem to be more or less monophagous and may be sampled from saplings or young trees but on the continent they are recorded from a range of Populus species including P. alba, P. deltoides, P. cathayana and P. nigra, and also possibly from Corylus and Salix. Mating occurs in the spring and oviposition from late May to late June; the female chews a small depression into the upper-surface of a leaf, deposits a small number of eggs and seals the hole with a secretion. Larvae hatch after a few days and mine the leaf communally, eventually producing a wide blotch mine which extends between the larger leaf-veins, the oviposition site is usually visible as a small translucent spot towards the edge of the mine, developing rapidly they pass through four instars and are fully developed by early July. During development larvae may be heavily parasitized by the ichneumon, Scambus inanis (Schrank, 1802) and the brachonid, Meteorus brevicauda Thomson, 1895. Fully grown larvae emerge through the upper surface of the leaf and drop to the ground where they burrow a few centimetres into the soil and pupate within a cell constructed from secretions and earth. Adults eclose from late July and either emerge to feed before overwintering among leaf-litter, tussocks or moss etc. or remain in the pupal cell to emerge the following spring; they begin to emerge in April and by early May the majority are active, at this time they feed upon host foliage producing small holes which may extensively perforate the entire leaf surface before they begin to mate a few days later.