Green Oak Tortrix (Tortrix viridana)
The Green Oak Tortrix is the only tortrix moth in our region which is entirely green. It is easily identified, for everything behind the head is light green. The head, antennae and legs are yellowish brown, the hind wings are grayish brown, just like in many other tortrixes. The wingspan is highly variable and may be anything between 16 and 24 mm. Most animals however hardly reach a wingspan of 20 mm. The only similar species is an Owlet Moth (Noctuid) called the Cream-bordered Green Pea. The latter however has white hind wings, always rests with the wings less flattened, but more upright and has a creamish line on the edges of the wing, while the Green Oak Tortrix is entirely green. The two species can thus be told apart easily. They can be seen together regularly, because both fly at the same time and prefer similar habitats.
The Green Oak Tortrix deposits its eggs in summer on tree trunks or tree branches near a leaf's bud. Usually most eggs are laid in the upper part of a tree. The eggs are laid two by two and don't hatch untill March next year. The young larvae bore into fresh buds and start eating these from the inside. Later they roll up a leaf (or simply fold it) to eat it. The larvae have an enormous appetite and grow very quickly. By the end of April, or the beginning of May the first pupate. The first adult moths appear some three weeks later. Young larvae are greyish brown and almost unmarked. The head however is clearly darker than the body is. From their third instar the caterpillars are greyish green or green with black dots scattered over their backs. The head is brownish black at first, but later turns into black. The caterpillars remain quite small, reaching a length of some 12 mm. Sometimes almost full-grown caterpillars change to other trees, but usually this species is bound to oak. The Green Oak Tortrix may appear in great numbers, sometimes resulting in complete defoliage of infested trees.
In Western-Europe, including Britain, there is one brood only, on the wing from the end of May to mid-August. In Northern Europe (like in Scandinavia and parts of Siberia) the Green Oak Tortrix often overwinters twice. In the Near East and Cyprus however two generations a year is the rule. The moth flies by night exclusively, but is regularly found in daylight resting on leaves. Comes to light in very small numbers only. Adult moths have a life span of some 5 days only. Common and often even numerous in most of Britain, provided there's some oak around. In other parts of Europe just as abundant. Not only common in Europe, but in Northern Africa and the Near and Middle East as well. Spreads eastwards into Kazachstan and Iran.