Biston strataria
| Biston strataria | |
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| Male | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Geometridae |
| Genus: | Biston |
| Species: | B. strataria |
| Binomial name | |
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Biston strataria (Hufnagel, 1767) |
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Biston strataria, the oak beauty, is a moth of the family Geometridae. It is native to Europe, but is primarily found in the United Kingdom. B. strataria is found in a variety of habitats, but is mostly found in woodlands where it rests on the bark of trees, camouflaged by its mottled black and grey wings. The male has feather-like antennae while those of the female are more thread-like. The moth has a wingspan of 40 to 56 mm (1.6 to 2.2 in).
The larvae are mainly brown with three lumps near the end of the abdomen. They have evolved to resemble sticks which helps protect them from predators. The larvae feed on many species of trees, but the most commonly used host plants are oaks.
The oak beauty has white forewings with two irregular broad brown bands along each wing. The first band is short, located near the base of the wing, and surrounded with a black border. The second band is located near the outer margin with a black border surrounding the inner edge. Between these two bands is a white space sprinkled with black dots as well as a crescent-shaped black mark near the middle. The overall appearance gives the oak beauty a mottled look. B. strataria‘s forewings are 17–27 mm (0.67–1.06 in) in diameter, while its wingspan ranges from 40–56 mm (1.6–2.2 in). The oak beauty’s hind wings are paler than its fore wings and have transverse black bands. The forehead and the front of the thorax are white while its sides are a white-grey blend. Its body is covered with many hairs. The back of the thorax and the body are a darker shade of brown.
The oak beauty exhibits melanism and comes in two different variations; a dark (melanic) form and light (typica) form. The melanic form is prevalent in the Netherlands, but this form has not been observed in Britain. Details explaining this discrepancy are not yet known. The closest relative to B. strataria is the peppered moth (Biston betularia), which also has two forms. The proportion of melanics is higher in B. betularia compared to B. strataria. This is unusual since, between the two species, it is B. strataria that should have a greater evolutionary selection for the prevalence of melanic individuals due to the higher pollution concentrations in the area.
Adult males possess feathered antennae and are frequently observed during the daytime. Such feathered antennae are thought to aid in sensing female pheromones from over a kilometer away (0.6 miles). This helps males locate females for mating.
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Wikipedia