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Moths of the month: May 2016

This is a monthly series illustrating several characteristic moths to look out for in our area. Text and photos by Roy Leverton.

You can also view the other months by selecting the links at the bottom of this page.

Rivulet (R Leverton)

Rivulet Perizoma affinitata

May & June, sometimes later.

Wherever red campion flourishes.

Throughout most of Britain, Rivulet is a species of open woodland and waysides, where its grub-like caterpillar feeds within red campion seedpods and the adult flies at dusk. In our area, however, it is mainly coastal. It is abundant on the Banffshire coast where its foodplant thrives in the guano-rich grassland. There the males fly actively in the mid-morning sunshine, a dozen sometimes in view at once, while egg-laying females flutter gently amongst the campion in the late afternoon.

In northern Scotland, many of our moths show slightly different habitat preferences and behaviour when compared further south, but Rivulet is an extreme example.

Click on the image to enlarge it.

Northern Eggar larva (R Leverton)

Northern Eggar Lasiocampa quercus callunae

Young larvae autumn to early spring.

Heather moorland.

Northern Eggar has a two-year life cycle, spending its first winter as a small caterpillar about an inch long. After hibernation these can be found in heather moorland basking in the spring sunshine, a habit shared with many hairy caterpillars.

These early instars are more variable and more brightly coloured than the full-grown caterpillar, yet at the same time they are quite well-camouflaged amongst the old brown and bleached heather.

Caterpillars and the resulting adults (see June 2015) are far more numerous in alternate years, odd or even depending on the region, probably due to an interaction with parasitoids.

Click on the image to enlarge it.

Beautiful Yellow Underwing (R Leverton)

Beautiful Yellow Underwing Anarta myrtilli

May into July.

Heather moorland.

This bright little arctic-alpine moth is probably present on every extensive heather moor, but recording it is not always easy. Because the adult is diurnal it never comes to light traps. Instead it is very active in bright sunshine, dashing about low over the heather, when the flash colouration of its black and yellow hindwings makes it hard for the eye to follow. In a brief glimpse it can be difficult to distinguish from some other insect such as a bee.

Thus the high percentage of red pre-2000 dots on its distribution map should not necessarily be interpreted as a decline. Instead, there may well have been a significant range extension, since all records in the Outer Hebrides are post-2000. It might also be worth targeting old squares to re-find this species for the forthcoming distribution atlas.

Click on the image to enlarge it.

Lesser Yellow Underwing (R Leverton)

Lesser Yellow Underwing Noctua comes

Caterpillar full-grown in May and June.

Most habitats, including gardens.

Lesser Yellow Underwing is among the most frequent caterpillars found by torchlight in spring, climbing plants and bushes to feed on the tender new growth. It is particularly conspicuous on broom, and on sallows when the buds are breaking.

Yet this caterpillar is rarely seen by day. It descends before dawn to hide at ground level in the leaf litter, protected by its sombre colour scheme with disruptive markings. Many other noctuid caterpillars follow a similar strategy, which protects them from foraging birds but exposes them to predation from small mammals such as shrews and invertebrates including beetles. Presumably that risk is worthwhile, for the adult Lesser Yellow Underwing is generally common later in the year.

Click on the image to enlarge it.

Common Pug (R Leverton)

Common Pug Eupithecia vulgata

May & June.

Most lowland habitats, especially gardens.

As its name implies, Common Pug is the most ubiquitous of the numerous brown pugs that cause so many identification difficulties. It will be present in almost every garden. With practice, it can be recognised by its biscuit brown and grey colouration, numerous paler and darker crosslines, and inconspicuously small discal spot. Its build and wing shape are subtly distinctive too, for those with a good eye for jizz.

On average, our Highland examples are more strongly marked than those from further south and have been given the subspecific name scotica, though whether they merit such status is questionable.

Curiously, the guide books describe Common Pug as double-brooded, but I have never seen a second-brood example even during 25 years in Sussex, and certainly not in Scotland.

Click on the image to enlarge it.

View other months

January - February




November - December

2008: May | June | July | August | September

2009: May | June | July | August | September

2010: May | June | July | August | September

2011: May | June | July | August | September

2012: May | June | July | August | September

2013: May | June | July | August | September

2014: May | June | July | August | September

2015: May | June | July | August | September

2016: May | June | July | August | September

2017: May | June | July | August | September

2018: May | June

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