Umber Moths
Under this name are included two species of Geometer Moths, belonging to the genus Hybernia (which see), viz., H. defoliaria, or the Mottled Umber (see Fig. 142), and H. aurantiaria, or the Scarce Umber. The latter species, despite its popular name, is by no means rare, while the former is abundant; though neither species is often seen, owing to the perfect insects appearing towards the end of autumn, and being nocturnal in their habits. The females have only stumps of wings, and, being totally unable to fly, they have to crawl up the tree trunks to lay their eggs on the buds. The males have large, conspicuous wings, and fly in search of the females. The two species of Umber Moths are nearly alike in size and form, but differ in colours and markings.
The Mottled Umber has the body brown, with two rows of dark spots on the back of the abdomen. The fore wings of the male are usually pale brown, with two dark brown, rather irregular cross-bands, and a dark central spot. In some males, the wings are reddish-brown, closely sprinkled with darker dots, and other variations are not rare. The larva feeds on almost all kinds of trees. It is cylindrical, and rather slender, with six true legs in front, and four prolegs or claspers behind. The back is brown, bordered on each side by a narrow, waved, black band, and crossed by grey markings. The sides are bright yellow; but the spiracles are white, and are surrounded by brown spots. The Scarce Umber Moth has the body orange-brown, with darker spots, as in the other species. The fore wings of the male are dull orange, with three darker narrow cross-bars, two near the base, and the other beyond the middle. Beyond the latter, near the margin, is a row of brownish spots. The hind wings are paler, and all the wings have a dark central dot. The larva feeds on White-thorn, and occasionally on Oak and Birch. It is at first deep yellow, but when full fed it is dark dusky-green, with a pale brown stripe down the middle of the back.
The pupae of both species are protected in slight cocoons on the surface of the ground.
Remedies. The females are unable to fly on to the trees; and they may be prevented from crawling up if a ring of tar and cart-grease, mixed in equal parts, is painted on the trunk near the ground, or on a belt of cloth or paper, or on a straw rope, fastened around the tree. The larvae may be shaken off by jarring the branches, and should be collected on sheets of cloth or paper and destroyed. All surface rubbish that could shelter the pupae should be cleared off.