No. 46 NEWSLETTER Summer 2000
WEST MIDLANDS BRANCH, BUTTERFLY CONSERVATION
Day flying Moths
Butterflies fly during the day and moths at night, don't they? Well, most of them do, but there are a few night-flying butterflies in the tropics, and in this country there are quite a lot of day-flying moths. Probably most of you will have seen some of these day-flying moths whilst out on butterfly trips. There are about 30 larger moths that normally fly during the day. In addition, a large number of moths that normally fly at night can be seen flying during the day, usually if they have been disturbed from their resting places. Unfortunately, some of the day-flying moths are quite tricky to identify with certainty, although they can usually be narrowed down to two or three species quite easily. Day-flying moths are as keen on sunshine as butterflies, and it is best to choose a mild and sunny spring day to look for them.
There are a few micro moth species that fly in daytime as early as February, such as Diumea fagella and Tortricodes alternella. These are both quite large for micros, and it can be quite disconcerting to see what at first glance might be 'small brown butterflies', flying around trees long before the first leaves have appeared.
The first day-flying macro-moth you might see is probably the Orange Underwing. This does indeed have a bright orange hind wing, and is a very pretty species. Its caterpillars feed on Birch, and it can be seen flying high in the trees in March and April, along woodland rides where Birch is present. It occasionally comes to the ground to bask in the sun; I was once lucky enough to have one next to me as I sat eating my picnic lunch in the spring sunshine. If your woodland contains Aspen trees, you might be able to find the rarer Light Orange Underwing, the caterpillars of which feed on Aspen. Otherwise it is similar in appearance and habits to the Orange Underwing; the easiest way to tell the two species apart is to examine the underside of the hind wing (see the diagram in Skinner's Colour Guide to Moths), but you will need to catch the moth first, which is not an easy task given its fast flight around the tree tops! However, since the Light Orange Underwing is a nationally notable species, any possible sighting of a brown and orange moth flying by day in March or April in woods containing Aspen should be reported. The Orange Underwings can be confused with Small Tortoiseshell and Comma butterflies emerging from hibernation. The moths are smaller, and fly with faster wing beats; they are most frequently seen out of the corner of your eye as they dash for the treetops!
A much more distinctive day-flying moth is the Emperor moth. This is the only British representative of the silk-moth family Saturniidae, and although not quite as big and spectacular as the tropical members of this family it is still pretty impressive, with large eye-spots on the wings. Only the male flies by day, although females can sometimes be spotted at rest, or as they emerge from cocoons. The male flies very fast in sunshine, and is said to be most active from about 3 pm onwards, from April to May. The female flies in the early evening. The Emperor is a characteristic heathland species, where it feeds on heather as a caterpillar, but it also occurs in a variety of other habitats such as commons, open woodland and marshes, utilising a range of foodplants including bramble, hawthorn and meadowsweet. The caterpillars are black and inconspicuous at first, but in their later stages they become bright green and quite large, and I have always found the caterpillar easier to spot than the moth. From eggs laid in May, the caterpillar becomes full-grown in August.
Another very attractive moth, in flight from May to June, is the Speckled Yellow. This is a fairly smalI geometrid moth, which lives up to its name: it is bright yellow with brown spots or blotches. It is a woodland species, with wood sage as its caterpillar foodplant, and can be seen flying in sunshine along rides and in clearing or scrubby areas.
One other moth that occasionally flies by day in March and April is the Yellow-horned. This is a stout-bodied moth, looking like a noctuid but actually a member of the family Thyatiridae. It has grey wings and distinctive yellow/orange antennae, from which it gets its name.
A most spectacular day-flyer is the Scarlet Tiger, a large black, red and yellow moth which can occur in huge numbers at its favoured sites. It is usually a wetland species, its caterpillars feeding on Comfrey and other plants. At Cothill in Oxfordshire, this species has been the subject of one of the most extensive wildlife studies ever undertaken, with regular monitoring since the 1940s and detailed work on the genetics of this variable moth. The Scarlet Tiger flies in June and July.
Two common day-flying moths should be out and about, flying in meadows and downland along with Dingy and Grizzled Skippers in late May and June. The moths in question are the Burnet Companion and the Mother Shipton. Since they inhabit similar places to the skippers, and look quite like skippers at first glance, they are often overlooked. Both moths are active fliers, easily disturbed, but with patience you should be able to get a good view of them at rest, when they can be identified fairly easily. The Mother Shipton is brown and grey with pale creamy markings, a bit like the Grizzled Skipper. However, instead of the Grizzled Skippers chequered pattern, the Mother Shipton's markings form the profile of a face on each wing. With a bit of imagination, this face can look like a gnarled old woman, giving rise to the name. Mother Shipton was a "prophetess and witch", said to have been born in a cave in Yorkshire in 1488. Among her exploits was foretelling the death of various prominent people, and predicting the invention of the steam engine and the telegraph. Quite why this particular witch had a moth named after her I'm not sure.
I assume the Burnet Companion is named after its occurrence in the same habitat as the Burnet moths (see below). At rest, it looks rather like the Dingy Skipper, although since it has orange on its hindwings it can look like a Small or Essex Skipper in flight. At rest, these orange hind wing markings are the easiest way to tell the moth from the Dingy Skipper (it often rests with its wings half-raised, like the skippers, so the hind wings can usually be seen).
Perhaps the most familiar of the day-flying moths are the Burnets, striking black and red moths that are commonly seen feeding on flowers such as Scabious. The easiest one to recognise is the Six-spot Burnet, which, as you might expect, has six red spots on each forewing. You might see forms in which the spots have become joined together to some extent, but these are uncommon. As well as the moths themselves, their cocoons are easy to find: these are oval, made of tough yellowish-white silk, and usually spun fairly high up on a grass stem. It has been suggested that the cocoons are spun on grass stems to make it difficult for birds to reach them, as there is nowhere for the bird to perch and peck at the cocoon. The moths are distasteful to birds, since their bodies contain a form of cyanide. Their bright colours warn of this, allowing them to feed safely on exposed flower-heads.
Rather more confusing are the Five-spot Burnets. There are two sorts, the Five-spot Burnet itself and the Narrow-bordered Five-spot Burnet. Annoyingly, these two species are very difficult to tell apart as adults, and to make matters worse the Five-spot Burnet has two subspecies, found in different habitats. The Narrow-bordered Five-spot Burnet is the more widespread species, and indeed seems to have increased as the Five-spot Burnet has declined
The Cinnabar is another common black and red day-flying moth which looks rather like a Burnet, although it is not related to them. Its markings are variable, but in addition to two red spots it usually has a red stripe on the leading edge of each wing. It has a more delicate flight than the rather 'buzzing' flight of the Burnets. Cinnabar caterpillars are very noticeable too, they are the black and yellow caterpillars which are sometimes found in large numbers on Ragwort plants, often completely defoliating them. The bright colours of caterpillar and moth again signify their distastefulness to predators.
The family Lasiocampidae contains a number of quite large 'chunky' moths with dense scales on their bodies, making them seem furry. Two of them are day-flyers (to be precise, it is the males that fly by day): the Oak Eggar and the Fox Moth. Both are predominantly brown; the Oak Eggar has one pale line crossing the wing and a white spot in the centre of the forewing, the Fox Moth has two pale lines and no spot. They are most often found flying on sunny afternoons. They fly very fast, and although at rest they are quite recognisable, the Oak Eggar in particular can look confusingly like a Dark Green Fritillary as it flashes past in a blur of orange-brown. The Oak Eggar is on the wing in July and August, the Fox Moth flies in May and June; both can be found in a range of habitats, especially on chalk downlands and heaths, and sometimes also open woods and commons.
I will end this brief survey of day-flying moths with three very different species from three different families. All three are commonest at the end of summer, although the last two are migrants and can occur earlier In the year as well; all three are regular visitors to gardens. The Vapourer is widely distributed and often breeds successfully in urban areas and gardens. It has an attractive hairy caterpillar, orange and brown with a tuft of longer hairs on its back. It feeds on a wide range of trees and shrubs. The adult female is wingless, and indeed remains in her cocoon for a male to find her and then lays eggs on the cocoon. The males have a fast, spiralling flight (in July-September, sometimes with a second brood in October), and on sunny days can often be watched flying for quite a distance in search of the female. In common with other species where the female is sought out over long distances, male Vapourers have feathery antennae, used to pick up the scent (or 'vapour') of the female
The Silver Y is entirely an immigrant species, migrating here from North Africa and Mediterranean Europe each year. Immigrants have arrived as early as January, but most arrive from May onwards. They breed here during the summer, and can produce a second generation in less than 50 days. Numbers build up with further immigrants on top of the UK-bred moths, and usually peak in late August/September, when garden Buddleias are a great attraction for them. There is some evidence of a return southwards migration during the summer. Silver Ys have a very fast wing-beat, almost hovering over flowers to feed, but for real aerial control the Humming-bird Hawk-moth is hard to beat. By Hawk-moth standards it is small, but is slightly larger than the Silver Y, and has a chunkier body. The moth is mostly grey, but its orange-brown hind wings give it colour as the wings beat in a blur, looking very like a small humming-bird. There are paler markings on the abdomen, which can usually be seen quite clearly as the moth feeds. It hovers over flowers (it too has a liking for Buddleia), keeping its body still while feeding through a long proboscis. Humming-bird Hawk-moths migrate here from further south in Europe, and as with Clouded Yellow butterflies there are good and bad years for them. A few turn up in most years, but they are rarely numerous and a sighting is always an event, prompting wonder at how this delicate insect can travel over such great distances. This article has not provided a complete list of day-flying moths, but I hope it may have encouraged you to look for moths amongst the butterflies.
The above article is a shortened version of the original, which appeared in the Upper Thames Branch Newsletter. – Ed