Zygaena purpuralis, the transparent burnet, is a moth of the family Zygaenidae.
Description
Zygaena purpuralis is a medium-sized moth with a wingspan reaching. Usually the forewings show three bright red longitudinal streaks quite variable in shape, with almost transparent greyish-bluish edges. Hindwings are more extensively or almost completely bright red. Head and thorax are black, while the abdomen is dark blue. Larva are yellow, with some lines of small black spots.
Technical description and variation (Seitz)
Z. purpuralis Brunnich. In this species the hindmargin of the forewing is all black, while the red wedge-spots situated before it may be shaped entirely as in erythrus Hbn. An aberration with light yellow instead of red markings, already recorded by Ochsenheimer, has more lately been named by Ruhl ab. grossmanni. It is said to have been observed as a constant or at least prevalent form in certain very limited localities. In ab. obscura Tutt the entire wings, inclusive of the red colour, is darkened. — sareptensis Stgr.-Reb. is a large, somewhat paler, lighter red form from South Russia. — diaphana Stgr., from Tauria, has thinly scaled, strongly transparent wings, the central wedge-spot being distally strongly widened. — nubigena Led. is also a very thinly scaled form from the high mountains of Europe and Asia, having moreover a very shaggy body, like Zygaena exulans, with which it occurs occasionally together. — In the rather large form smirnovi Christ., from Turkestan, the distal wedge-spot is constricted before its dilated apex. — pluto O. has a black apex to the hindwing and the central streak of forewing is entirely of even width, not in the least being dilated distally; in South Europe, as far north as Austria. — In polygalae Esp. the black interspaces between the red streaks have entirely disappeared the red being so extended that the forewing is only edged with black, differing from Zygaena rubicundus in the hindmargin of forewing being black ; in the South, especially Northern Italy. — In heringi Zell., from North Germany, the antenna is thinner and the central wedge-spot of the somewhat broader forewing extends to near the distal edge. — In ab. interrupta Stgr. the central streak is broadly interrupted and the posterior one often constricted in middle; more in the North of the area, among the name-typical form. — If all three streaks are interrupted, the red is separated into 6 spots, recalling the pattern of other Zygaenas; this form is ab. sexmaculata Burgeff. — Finally, there occur also specimens which have a red abdominal belt: ab. cingulata Burgeff — Larva bluish white or light yellow; a subdorsal row of heavy black dots; head, pectoral legs and stigmata black.
Biology
Adult moths are on wing from late May until August, depending on location. They fly during the day, especially with warm and sunny weather, feeding on nectar of various flowers. The larva feed on wild thyme. They occur from August to May and overwinter once or twice.
