Although the Lulworth skipper (Thymelicus acteon) has a very restricted distribution in the UK – along the south coast of Dorset – it is widespread and abundant in Spain, where it is known as the Dorada oscura (Dark gold). This species likes humid conditions which is why it is often found in coastal locations where the caterpillars feed on grasses in the genera Brachypodium, Calamagrostis and Elymus.
On a rather damp and overcast day in NW Spain – butterflies are often very active in such summer conditions – in late June, I came across a pair of courting Lulworth skippers which I was able to follow, briefly, and photograph. They were – as skippers usually are – very active, and the light was not conducive to great photographs, but I did manage to capture a few images of their courtship behaviour. It all of the images, the male was located behind or below the female as they flittered about on some ferns.
There is not a vast literature on the mating behaviour of skippers, indeed I could only find a handful of papers, and none on this particular species, Thymelicus acteon. What comes across though, regarding the love life of skippers, is that it is usually rather short and sweet! At least compared to other butterflies, such as the Grayling or the Rock Grayling, where the courtship behaviour is elaborate and consists of a series of complex courtship sequences (See previous blog on the courtship behaviour of the Rock Grayling (Hipparchia hermione). Indeed, as one author – Matthew Oates – eloquently put it in a recently published book: “Some butterflies have elaborate courtship displays, many do not, and the Lulworth Skipper falls comfortably into the latter bracket”. (1)
So it seems that the Lulworth skipper, and probably Skippers (Hesperiidae) in general, have something of a reputation for being brief and to the point when it comes to love-making! The courtship behaviour of a North American species, the fiery skipper (Hylephila phyleus), was described as being ‘brief and not very elaborate’ (2). Whilst this may be true compared to some other species, there nevertheless appeared to me to be quite a lot going on between these courting butterflies, shown here, not all of which I could understand. In other skippers – like the fiery skipper, a series of courtship phases, or sequences, have been observed. Prominent among these is something called ‘head-wing behaviour‘, where the male, standing behind the female, ‘thrusts his head between the female’s hind-wings, touching the upper surface of her wings and the rear of her abdomen with his head and antennae’ (3). There is also a good deal of fluttering behaviour – by both sexes – before coupling occurs (or, as in this case, they fly off on their separate ways).
As is the case in most butterflies, either sex may terminate the courtship if they are not to each others’ liking. In the Essex skipper (Thymelicus lineola) both males and females have refusal displays, by which they can end the affair. (4) These fluttering and refusal dances allow each butterfly to evaluate each other – using visual and olfactory (scent) cues – and decide whether they like each other. In other words, they can literally smell whether the other butterfly is attractive. The pheromones produced by the male provide signals containing a wealth of information by which females can determine his size, health and status – and hence desirability. In this way she can make her choice from the pool of available suitors.
I was also very interested to capture an image of the male Lulworth skipper extending his proboscis as he was located directly behind the female. Wood white male (Leptidea sinapis) butterflies also extend their proboscis during courtship (see previous blog: Wood whites go A-Courting!).
Male skippers have prominent stigmata (also called sex brands) on their fore-wings; these are raised patches of specialised scales called androconia. These androconial scales vary from species to species, but usually have a bulbous base – containing the pheromone – which tapers to a fine point with a tuft of tiny hairs on the end, to disseminate the chemical. The sex brand on the Lulworth skipper – especially on the dark forms of this species – appears as a fine line at an oblique angle (see here), not usually as prominent and conspicuous as that on the Large Skipper (see below), although these features can vary.
The male pheromone is released during courtship and affects the receptivity of the female to the male. Research on the Essex skipper (Thymelicus lineola) suggests that female skippers can assess the age and mating status of a male via the quantity or quality of male pheromone released during a given interaction. (4, 5) The androconia fracture, and pieces called osmophores break off and release the pheromone(s). During courtship, the male may transfer his pheromones to the female both directly – by contact between the female’s antennae and his androconial glands – or indirectly, as a vapour or aerosol, as the male hovers around the female during courtship.
The sex brands, or stigmata are also visible on the ventral side of the wing, as can be seen in this Large Skipper (below), nectaring on a dog rose (spot the green beetle as well!).
Male skippers usually perch on prominent sites on the look-out for passing females (see below). When a female passes, the male gives chase and after approaching closely they both land and courtship continues. The male usually takes up a position behind the female.
The more I look at butterflies and try to gain some sort of understanding of their behaviour, the more I am struck by how little we know. Whilst there are some excellent studies in the literature, there is still a dearth of knowledge, particularly when it comes to mating behaviour. The advent of high quality digital cameras – even mobile phones are fantastic now! – has opened up the field to anyone who cares to spend the time looking and recording. They may record something that was little-know or previously unrecorded. Butterflies have always been the preserve of the amateur, but never more so than in this digital era we live in.
The photographs of the Lulworth skippers were taken in Galicia, Spain, at a site near to Cape Bares (see below) on 22 June this year (2017).
- Oates, M. (2015). In Pursuit of Butterflies: A Fifty-year Affair. Bloomsbury Publishing.
- Shapiro, I. D. (1977). Interaction of population biology and mating behavior of the fiery skipper, Hylephila phylaeus (Hesperiidae). American Midland Naturalist, 85-94.
- Shapiro, I. (1975). Courtship and mating behavior of the fiery skipper, Hylephila phylaeus (Hesperiidae). Journal of Research on the Lepidoptera. (Available online in the archives of http://lepidopteraresearchfoundation.org/)
- Pivnick, K. A., & McNeil, J. N. (1985). Mate location and mating behavior of Thymelicus lineola (Lepidoptera: Hesperiidae). Annals of the Entomological Society of America, 78(5), 651-656.
- Pivnick, K. A., Lavoie‐Dornik, J. A. N. Y., & McNeil, J. N. (1992). The role of the androconia in the mating behaviour of the European skipper, Thymelicus lineola, and evidence for a male sex pheromone. Physiological entomology, 17(3), 260-268.
- Scott, J. A. (1973). Adult behavior and population biology of two skippers (Hesperiidae) mating in contrasting topographic sites. J. Res. Lepid, 12, 181-196.