Carpet and pug moths are named for their small size and attractively patterned wings, not because of carpets and dogs.
There are over 6,000 species of Carpet and Pug moths worldwide. Carpet moths are named after the patterns on their wings, which are likened to a carpet design in their intricacy. The patterns generally consist of wavy lines of color on a pale background, often with a central band of another color. The underwings are usually much duller and only faintly patterned.
Carpet and pug moths together make up the sub-family Larentiinae of the large moth family Geometridae.
Color and Pattern
Carpets and pugs are small moths with wingspans varying from as little as 12mm (1in) to 4cm (1 1/2in). Carpet moths are named because of the intricate, carpet-like patterns they display on their forewings. The underwings are more uniform, with some faintly barred.
The patterns on the forewings may consist of a series of wavy or angular lines of varying extent and different colors superimposed on a pale background color. There is frequently an additional, solid, central band of color angled towards the wingtips.
Few species are brightly colored, although some are yellow or reddish or bear patches of blue or purple. An unusual feature of the Larentiinae is that the predominant color in several species is green, which is normally rare in the Lepidoptera. Typical green species are the green carpet, autumn green carpet, and the green and V-pugs.
Many species display considerable color variation, frequently linked to their geographical distribution. An example is the attractive netted pug, which exists as four sub-species in the Scottish islands. The Scottish and Irish races of the yellow shell, another variable species, are darker than the typical delicately banded yellow form.
The forewings of the variable common marbled carpet may be whitish, rusty yellow, or even nearly black. Many other species of carpet moths are very similar to each other, and some were at one time considered to be merely races or varieties of one main species.
Pug moths are particularly difficult to identify, mainly because of their small size and variable patterns. In some cases, the only sure means of identification lies in the removal and microscopic examination of the male genital claspers.
The wing patterns of most carpet and pug moths enable the insects to merge with their surroundings when at rest during the day. Such patterns often give the appearance of tree bark, as in the case of the small waved umber.
This species has a broad lateral stripe on each wing which joins to form a single, continuous irregular streak resembling a fissure in the bark. This pattern also helps to break up the moth’s outline, further protecting it from predators.
Another camouflaged species is the yellow-ringed carpet found on moorlands. It has yellowish scales on its wings which blend with the moss-covered stones on which it rests by day.
Larentiinid caterpillars are also difficult to spot because of their small size, cryptic coloration, and habit of resembling twigs when resting. Some species are less colorful because they feed inside flowers or seed capsules, where they have little need for protection. The caterpillar of the cloaked pug, which feeds within spruce cones, is a prime example.
How Do Carpet and Pug Moths Fly?
Both carpet and pug moths fly in a rather weak, fluttering manner. Most moths are active only at night when they are frequently attracted to artificial light. However, several species, including the July highflyer and the treble-bar, fly during the day, usually on sunny days.
One of the larger members of the family, the treble-bar, can be recognized by the three irregular bands of lines across its ash-grey, reddish-tipped forewings. It can be found in calcium-rich regions, especially where its larval food plant, St John’s wort, grows.
An unusual and distinctive day-flyer is the little chimney-sweeper which is uniformly black except for a narrow streak of white on the tip of its forewings.
Although most carpets and pugs fly during the summer, some exceptions exist. The Shoulder-stripe, for example, is seen in March and April, whereas the drab-colored Mallow flies in the autumn. A few species, including the aptly named November and winter moths, emerge in the winter and can be seen flying from October to February. Another variation in the life cycle is seen in the tissue moth, which overwinters as an adult to emerge again the following spring.
Eggs and Caterpillars
The moths lay their eggs on various trees, shrubs, and other plants, both wild and cultivated, with low-growing species such as bedstraws being preferred by many species.
Larentiinid caterpillars are of the ‘looper’ type. Their false legs (pseudopodia) are reduced to two pairs of hind claspers, and they move in a very distinctive fashion. The caterpillar will first thrust its head forward and takes hold with the six true legs just behind it.
It then draws its body close behind so that both true legs and hind claspers are adjacent, with the body forming a loop. This method is common to all Geometridae.
Pug moth caterpillars feed on the flowers, stamens, and seeds of various plants, which involves them in interesting lifestyles. Foxglove pug caterpillars feed within the tubular flowers of foxgloves, sewing up the edges of the flower with silk to form a retreat.
Some carpet caterpillars do similarly, one example being the rivulet, whose caterpillars consume the unripe seeds of campions and ragged robin. Cultivated plants, especially brassicas, are another source of food.
Several species overwinter as eggs or caterpillars, but most pupate in silken cocoons in the soil beneath the food plant. Many species breed early and produce two or more broods of adults during the year.
Where Do They Live?
Many of the commoner carpet moths can be seen in gardens and hedgerows. The yellow spinach is a common garden dweller, deriving its name from its habit of resting on spinach plants, although its larval food plant is currant bushes.
Common species with similar coloration are the handsome barred yellow and the paler barred straw, which can be recognized by how it rests, with its wings curiously up-folded.
The garden carpet, the silver-ground carpet, and the common carpet are three very similar common species. They all have whitish wings with grayish-black or brownish wing-bars and are easily confused.
Chalky soils and scrubland are the homes of species such as the wood carpet, chalk carpet, pretty chalk carpet, and Haworth’s pug. The caterpillars of the last two species may be found feeding on travelers’ joy.
Typical woodland species are the handsome blue-tinged beautiful carpet and the striking black and white argent-and-sable, normally found around birches. The spruce carpet and cloaked and larch pugs are found in coniferous woodland.
The scallop shell and the Manchester treble-bar are found on moorland, where their caterpillars feed on bilberry and other low-growing plants.
Seashores and saltmarshes also support some species, such as the scarce pug, whose caterpillars eat only sea wormwood and related plants. Other species are typical of fens and water meadows. They include the oblique carpet and the distinctive yellowish-brown and black marsh carpet, which is now increasingly rare due to drainage of its habitats and loss of its food, meadow rue.