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Moths of the month: September 2017

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.

Brindled Plume (R Leverton)

Brindled Plume Amblyptilia punctidactyla

September-October, then again in spring after hibernation.

Damp shady places, woodland edge.

All members of the distinctive micro-moth family Pterophoridae have a similar build to craneflies, with very long legs and narrow forewings. Their flight is feeble, but despite their fragile appearance some species hibernate, including this one.

Brindled Plume is not often encountered in our area, which may partly be due to its secretive habits. Hedge woundwort growing in damp shady places is the usual larval foodplant, and in northern Scotland there is probably only a single brood. Adults emerge in September and are occasionally attracted to lighted windows, or seen nectaring on flowers such as ragwort and buddleia after dark.

Click on the image to enlarge it.

Spruce Carpet (R Leverton)

Spruce Carpet Thera britannica

Almost any month, but peaking September-October.

Coniferous woodland, sometimes parks and gardens.

Until about 30 years ago, Spruce Carpet reached no further into Scotland than Dumfries and Galloway. Since then it has rapidly extended its range northwards as far as Caithness, and is now abundant in suitable habitat throughout the Highland region.

As the moth’s name implies, spruces are the main larval foodplant, though other firs and pines are also used. There are two broods per year, but whereas both broods are of similar size in southern England, in our area the autumn brood is by far the more numerous. During mild winters, a few individuals are still flying in December.

Because both species are so variable, some forms of Spruce Carpet can resemble Grey Pine Carpet and vice versa. Ironically, Spruce Carpet is generally greyer than Grey Pine Carpet despite the latter’s name.

Click on the image to enlarge it.

Gray Dagger larva (R Leverton)

Grey Dagger Acronicta psi

Larva full-grown in September.

Woodland, scrub, hedges, gardens.

Most caterpillars rely on disguise to escape their enemies, but a few species take the opposite approach, advertising their distastefulness by bright colours and distinctive patterns. While this may be effective against birds, it does not deter their invertebrate enemies such as tachinid flies and ichneumon wasps. Remarkably, the caterpillar figured here survived a parasitoid attack and successfully pupated after the grubs had exited, producing a moth the following June.

Although it has some preference for rosaceous trees and shrubs, Grey Dagger can also use a wide variety of other trees such as birch. Its larva is a regular autumn find in gardens both rural and urban, when its striking pattern is sure to attract attention even from casual observers. Ironically, the adult moth is cryptic, relying on its camouflage.

Click on the image to enlarge it.

Narrow-winged Pug larva (R Leverton)

Narrow-winged Pug Eupithecia nanata

Larva full-grown in September.

Heather moorland.

By September, most vegetation has lost the vibrant greens of early summer and is beginning to look a bit tired. Caterpillars that were well-camouflaged when their foodplant was fresh now risk standing out because they are too bright a green. This is what drew attention to the green form of Narrow-winged pug larva shown here. The purplish pink form, slightly more frequent on that hillside, matches the bell heather flowers instead.

Fortunately by autumn most insectivorous birds such as Meadow Pipits have left the moorland, and in any case these larvae are almost ready to pupate.

Click on the image to enlarge it.

Lunar Underwing (R Leverton)

Lunar Underwing Omphaloscelis lunosa

September into October.

Open dry grassland.

In Scotland Lunar Underwing occurs on low ground at or near the coast, avoiding upland and inland habitats. In our area it is quite local, mainly found in the inner Moray Firth and on parts of the west coast including Skye and the Uists. Since grasses are the foodplant, light well-drained soil and a mild winter climate for the overwintering larva may be the determining factors.

The flight period is quite short, during September and early October. The adult is mainly seen at light, but also feeds on overripe berries after dark, including those of elder. Although it is very variable in colour and pattern, the lighter veins are a good identification feature, particularly noticeable in the darker forms. Otherwise the distinctive hindwing is the key.

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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