Small Skipper Thymelicus sylvestris
Family: Hesperidae, (The Skippers)
Michelle Smart
Status
Still common and widespread but while extending its range in the North and West is declining in many localities . From its zenith in the mid 90's when it was the most common grassland species it is now Yorkshire's most rapidly declining widespread species. Where once there were 3 figure counts on good sites now it is in the tens.
Identification
Female by Catherine Jones
Michelle Smart
Catherine Jones
The Small Skipper is one of our three golden skippers species in Yorkshire. When at rest the forewings are often held upwards in a V-shape, and hindwings horizontal and with its unusually large body gives it a very moth like appearance. This is characteristic 'skipper' fashion earning its nick name of 'bull head'. With a wingspan is 27-34mm freshly emerged specimens are golden brown with a narrow black margin that becomes drab when worn. The undersides are much paler. Male and females are alike except that males have a sex brand, which is a thin, black, slightly curving line on upper forewings. Their flight is fast and darting and the butterflies can be hard to see when nectaring or resting on flowers because of their brown-ish colour. They respond well to sunshine and fly about but drop down into vegetation or become very still if the sky clouds over or it rains.
The Small Skipper is of often confused with the Essex Skipper and it takes some practice to tell them apart. Previously the Essex Skipper was extremely rare in Yorkshire so this was not an issue but it is now becoming more common and appears to be gradually moving north. Therefore it can no longer be assumed that all small golden skippers are Small Skippers.
Small Skipper underside antennae tips are rather variable, from orange brown to dark brown and can look as though they have black tips, but with rather blurry edges and the darkness extending above and below the tips. However Essex Skippers have sharply defined, glossy black tips to the underside of each antenna. lt looks like the antennae tips have been dipped into black ink, leaving a stain on the undersides, but not the uppersides. The antennae are often bright orange-brown above and paler underneath, with the black tip forming a sharp contrast. They can also be darker with an orange-brown patch adjoining the black tips.
Another difference is that the sex brand of a male Small Skipper is long and at an angle to the edge of the wing, whereas male Essex Skippers have shorter, straighter sex brands, which are parallel to the forewing edge.
ID Tips
All the skippers are capable of flying at such a speed in warm weather they are a blur. Their flight is often very straight and directional and along with their small size gives us our first clues. If it is predominatly a greyish or dark blur then its likely a Dingy rather than one of the golden skippers. The Skippers actually derive their name from when flying slowly amongst long grasses with their characteristic skipping or' jinking of short wings beats maneovouring between stems. While at rest it takes a mothlike posture is the next clue.
The largest source of confusion of Small Skipper is with Large Skipper but is very easily distinguished at rest by the presence of light spots on the upper and lower wings. Indeed any spots makes it a Large skipper. Habitat will also give us a clue when Large skippers very much favour damper areas with lusher grasses plus also emerge nearly a month earlier so are decling by the time Small skipper emerge You only need to attempt the differentiate Essex skipper if your site is know to have them .
Speed, size, spots, habitat, date
Habitat
The Small Skipper likes open areas, but with tall clumps of the larval foodplant grass Yorkshire Fog a common grass which grows on many soil types.
Almost any habitat where grasses are allowed to grow tall may be suitable; e.g. road verges, open woodland rides and old industrial sites and can also be seen flying in very exposed places such as high open moorland. Although it is not a typical garden butterfly, adults may visit gardens and nectar on Buddleia.
Trends
Before around 1970 the species was rare in Yorkshire. Over the last 50 or so years the species has been rapidly spreading around Yorkshire and is now found throughout the county and at most heights except the highest peaks. However it still lives in local colonies in grassland habitats. It is often under recorded because it goes unnoticed and also females are often lower down in the grass and so not counted.
Small Skippers do not like machine cut or grazed grass and so may be partly expanding north due to the new wide verges of the A1. Overwintering larvae may be lost if grassland is heavily grazed or machine cut after egg laying.
There is a consistent long term decline of Small Skipper which continues a pace having lost 50% in abundance since 2003 which is worrying for what used to be our most common grassland butterfly. Year to year it shows a great variation in abundance by a factor of 5+ but generaly follows the weather patterns booming in 2006 then again in 2014, both good summers but this was not repeated in 2018-19. There are signs the trend is stablising at a lower level but there has been no repeat of the booms in the present run of good summers.
There may well be a combination of factors of not only higher temperatures but also nitrogen deposition altering habitat and suitability of grassland, We are already beginning to loose this species from some of our managed sites
Abundance Trend (Average transect indices) -59% with a correlation 0.25 (weak)
Occupancy Trend ( % of visited tetrads)
-27% with a correlation of 0.71(strong)
Distribution Trends
Life Cycle
There is only one brood each year, flying from late June till August.
Female Small Skippers fly unusually slowly when searching for suitable grasses on which to lay eggs. They then crawl backwards down the stem, keeping their abdomens in contact with the surface, until meeting the opening of the furled leaf sheath. Inside this they deposit a row of up to eight white, oval eggs. A single blade may sometimes hold several batches from different females, but apparently never more than eight from any one individual.
Eggs become creamy-yellow with age and hatch after three to four weeks. Each larva eats its eggshell then spins a silken cocoon around itself and immediately hibernates inside the grass sheath until the following spring. By going straight into hibernation it can make the most of feeding on fresh growth the following year.
Larvae are green with three pale stripes and, post hibernation, develop through five instars, until June or early July, when green pupae are formed at the base of a grass clump inside a protective tent made by binding leaves together with silk. The adults emerge after about two weeks.
Over much of the county the adult peak is usually in mid-July, although wet weather in late June may cause this to be later. Emergence can be later in the north and west and on high ground. Some specimens are still around in September. Adults nectar on lots of different plants, including scabious, knapweed, thistles, trefoil and vetch.
Flight Curve
Aberrations
Only 13 variations have been described, mainly affecting ground colour: e.g. silvery cream in ab pallida Tutt; yellowish white in ab margarita Frohawk, and chocolate brown in ab brunnea Verity. Melanism also occurs, both partial, as in ab obscura Tutt, and complete, as in ab sutfusa Tutt.
With thanks to The Butterflies of Yorkshire edited by Howard M Frost
Catherine Jones 04/01/21