DISTRIBUTION:

Aglia tau (wingspan: 2.5-3 inches/52-75mm // forewing length: males: 30-36mm; females: 36-49mm) ranges from Japan to Europe: northern France and Spain (600 to 1500 m) into Scandinavia and much of central Europe with males tending to a more orange colouration than the yellower females. Tau is not found in the United Kingdom, nor is it found in the Mediterannean Region.

The species gets its name from the "T" shaped white markings in the four ocelli of the wings. There are many forms, two of which, courtesy of Andrey Timchenko, are depicted below.

Aglia tau f. melaina (f. melaina Gross, 1898)
See additional images of live Aglia tau f. melaina courtesy of Martin Jagelka.

Aglia tau f. ferenigra (f. ferenigra Thierry-Meig, 1884)
See additional images of live Aglia tau f. ferenigra courtesy of Martin Jagelka.

Melaina are heavily dusted with dark-brown or black scales and are especially common in cooler, mountainous areas. In ferenigra, the submarginal areas of all wings are heavily dusted with dark scales.

Recently (2015) a new species, Aglia sinyaevi was described from Shaanxi, China, by Brechlin & Meister. A. sinyaevi is very similar to but slightly smaller than tau, and the forewing pm line of sinyaevi is slightly closer to the outer margin (more outwardly convex) than in tau. The HT of sinyaevi has a very generous suffusion of dark scales in the basal and marginal areas of all wings, but with only two specimens examined, one male and one female, it is not clear if the darker marginal area is a consistent character of sinyaevi as tau specimens can be quite melanistic.

There still appears to be some disagreement with regard to subspecies of Aglia tau. Based on a publication by Naumann, Brosch and Nassig, 2003, specimens previously designated as subspecies of tau are placed in synonymity with tau. Many people still regard specimens from Russian Far East, northeastern China, the Koreas as Aglia tau amurensis.

Aglia tau male.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

This species flies from March until June depending upon location and spring temperatures.

The preferred foodplant is birch, but tau also accepts beech, lime, oak, sycamore and walnut.

Aglia tau female, courtesy of Tony Pittaway.

ECLOSION, SCENTING AND MATING:

Pairing takes place from morning until noon, but females (often twice the size of the male and pale in comparison) deposit their eggs under the cover of darkness. Calling females are often located by rearers by tracking down the day-flying males.

Males have large bipectinate antennae while females have almost filiform ones.

EGGS, LARVAE, COCOONS AND PUPAE:

Large, pale brown eggs are smooth and shiny and are shaped like beans. Image of eggs supplied by Hideshi Naka, Japan. The eggs are deposited in masses or rings around twigs with incubation usually lasting 11-15 days.

Larvae like lots of room, do not move a great deal, and feed in solitude. Crowding larvae in artificial situations will almost certainly result in their deaths. In the first instar, bifurcate spikes of red, black, and white adorn the body. The second instar larva to the right has less colouration, but spikes are still quite long.

As larvae progress, spikes diminish in length, and light green colouration predominates as is evident in this third instar larva. Second and third instar larvae courtesy of Paolo Mazzei.

In the final instar, larvae are translucent, without spikes, and look as though made out of green wax. The larvae pupate near the surface in moss, leaves, or dirt with just a few strands of silk for support. Pupae are short and rough on the surface with stiff bristles on the tail.

Aglia tau first instar on Corylus, Czech Republic,
courtesy of Jurgen Vanhoudt.

Aglia tau third instar on Corylus, Czech Republic,
courtesy of Jurgen Vanhoudt.

Aglia tau fifth instar on Corylus, Czech Republic,
courtesy of Jurgen Vanhoudt.

There is the almost black aberration of Aglia tau, ferenigra, with only the inner area of the wings ochrous. Some forms are almost entirely black.

It is hoped that this alphabetical listing followed by the common name of the foodplant will prove useful. The list is not exhaustive. Experimenting with closely related foodplants is worthwhile.

Acer pseudoplatanux Alnus cremastogyne Alnus japonica Betula alba Betula pendula Betula platyphylla Carpinus betulus Castanea crenata Corylus avellana Corylus heterophylla Fagus crenata Fagus longipetiolata...... Fagus sylvatica Ilex verticilata Juglans regia Platanus Pyrus communis Pyrus malus Quercus dentata Quercus robar Quercus serrata Salix capraea Tilia

Sycamore maple alder Japanese alder White birch Silver birch Japanese white birch European hornbeam Japanese chestnut European hazel Hazel Japanese beech Beech European beech Black alder English walnut Sycamore Pear Apple Daimyo oak English oak Konara oak Sallow/Goat willow Basswood/Lime/linden

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The pronunciation of scientific names is troublesome for many. The "suggestion" at the top of the page is merely a suggestion. It is based on commonly accepted English pronunciation of Greek names and/or some fairly well accepted "rules" for latinized scientific names.

Often names were chosen without any direct link to the characters of the genus or species.

The suggested pronunciations, on this page and on other pages, are primarily put forward to assist those who hear with internal ears as they read.

There are many collectors from different countries whose intonations and accents would be different.

In Greek mythology, Aglia is one of the Graces and is the wife of Hypnos. Also known as Pasithea, Aglia is the mother of Morpheus.

The species name, tau, is for the "T" (tau) in the hindwing ocellus.

Aglia ingens: original description, 2003; 2015, B&M, designate ingens as a subjective junior synonym of homora.