About Idaea seriata minuscularia (Ribbe, 1912)
Idaea seriata minuscularia (Ribbe, 1912) is an extremely variable species, with forms ranging from almost pure white with no markings or well-defined lines to solid black-grey. In all forms, the head vertex stays whitish, while the collar is dark. When lines are present, they do not originate from enlarged costal spots, though the costal end of the lines is often slightly darker than the rest of the line. The first forewing line is angled along the subcostal vein, or at least sharply bent, and is thickened with dark markings on the veins. The median shade is thicker; it is often quite strongly developed, but may also be completely absent even in forms where other lines are sharply defined. On the forewing, the median shade usually touches the cell-spot, and on the hindwing it is always located proximal to the cell-spot. The postmedian line is fine and grey, not conspicuous on its own, but marked with strong, coarse black spots on the veins. It sits fairly close to the distal margin, curving inward between the radials before curving outward; this line's shape is best illustrated on the right forewing in the referenced figure, and is comparable to the more developed shape seen in calunetaria. The pale subterminal line curves or angles slightly more sharply inward between the radials. It is often almost unrecognizable because it lacks accompanying dark shading, but this dark shading can also be moderate or very strong; it sometimes almost fills the entire distal area to form a dark border along the wing edges. Unlike the dark shading seen in species such as Idaea incisaria (Staudinger, 1892), Idaea camparia (Herrich-Schäffer, 1852), and Idaea sodaliaria Herrich-Schäffer, 1852, this shading almost never breaks up into spots. The distal marginal line is made up of a series of black dashes of varying thickness, and is sometimes nearly absent. The fringe has more or less prominent dark dots at its base, positioned opposite the vein ends. The underside of the forewing is more or less suffused, often dark smoke-colored, but the postmedian line and cell-spot are usually still clearly visible. The underside of the hindwing is white or whitish, with markings matching or not matching the upper surface of the individual form, following the same pattern of variation. The typical Idaea seriata found in Central and Northern Europe is more or less heavily dusted, giving it a grey appearance, but it covers a wide range of smaller variations. These variations affect the intensity of dusting, and the definition of lines, the median shade, or dark bordering, either individually or in combination. This species produces either one or two generations per year, and can be found on the wing between June and September in the British Isles; flight seasons may vary in other parts of its range. It flies at night, and will sometimes come to light. The larva feeds on ivy, and the species overwinters in the larval stage.
