This Year's Butterfly Findings from Gästrikland 1994 (Lepidoptera)

The spring season started fairly normally according to the calendar, and Orthosia gothica (common sallow moth) and Brachtonycha nubeculosa (spring gothic) appeared in Mårtsbo for the first time on 1 April. May was comparatively cold, June was colder than May and we began to worry quite a bit that summer would fail to arrive altogether. From the end of June the weather stabilized, temperatures rose and a long, dry and warm period began. The midsummer heat continued then right up to 6 August when an unsettled period began. Although the fine weather resulted in unusually high water temperatures in the Baltic Sea, September weather was normal for the season. Already on 4 October came the first cold snap with abundant snowfall. Autumn then remained cold until the end of November when warmer air temporarily flowed in from the southeast. By this point we begin to recognize the pattern from the three most recent autumns.

The first part of this year's butterfly season was, compared with the corresponding period in 1993, not unexpectedly quite poor, and midsummer, despite unusually favorable weather conditions, yielded surprisingly meager catches. Throughout, the number of individuals of most larger moth species was low. The cold autumn of 1993 has probably been fatal to several species that were then larvae and dependent on reasonably normal temperatures for their development. Within the Acronicta (sombre prominent) group of flies, for example, the number of individuals both in Lågbo and around Gustavsmuren decreased markedly from 1993 to 1994. Orygia recens (rosy marsh dagger), which was relatively common in the power line corridors at Gustavsmuren in 1993, was not found in 1994. Coenocalpe lapidata (mottled umber), a northern species that has expanded in southern Gästrikland over a period of years, was by contrast record common. Approximately half of all butterflies that visited lights in Mårtsbo during September 1994 were mottled umbers and the species was also very abundant in Lågbo. Studies of variations in butterfly fauna in northern Finland have shown that the weather of the previous season, not the weather at the time of investigation, determines the composition of the fauna (Linnalvoto & Koponen 1980). People tend to say "the weather at the time of capture determines how much of what exists that shows itself; last year's weather determines what exists"!

The Society's environmentally fundamental-minded butterfly committee visited, among other activities in 1994, Eggegrund and continued work on investigating and documenting the rich butterfly fauna of the Trösken area. New in this year's harvest from "the area around the non-railway bank" are: Coleophora lineola (stinking groundsel case-bearer) (threat class 2), which this year has been found in Gästrikland for the first time, and Caryocolum viscariella (catchfly case-bearer) (4 ABC). Furthermore, Nola karelica (Karelian nola moth) (threat class 4) was refound at its old locality, where the species has not been recorded since the 1960s (RYR).

The Eggegrund survey was reported separately in the previous issue of Insectifera (Källander 1994b), but some of the year's most exciting finds merit mention here as well: Pterophorus baliodactylus (royal mint plume moth) (threat class 4), Depressaria pulcherrimella (lovely depressaria) (threat class 4 ABC), Pyrausta aurata (golden-light moth) (threat class 4 ABC), Euzophera cinerosella (wormwood moth) and Apamea lithoxylaea (wood-colored meadow fly). All these species can be classified as bound to rich dry grasslands and show that the island has a faunal composition unique for our latitudes.

The Gästriklands Entomological Society had two excursions during the year to the abandoned farm Skarven between Brännsåger and Oslättfors. The area has many rich cultural biotopes; from dry meadows and pastures to rich fens and swamp forests. Interesting finds from the Skarven excursions include Coleophora lineola (stinking groundsel case-bearer) (threat class 2) and Eupithecia immundata (immune pug) (threat class 4).

Another major project has been to study the butterfly fauna around the coastal meadows in Lågbo, Hedesunda (Lundin et al 1993). The Lågbo studies, which ended in autumn 1994 after running for three years, yielded nothing new during the year. Prays fraxinella (white ash bud moth), Agnopterix hypericella (pretty St. John's wort plume moth), Eupoecilia ambiguella (European grapevine moth), Ancylis mitterbacheriana (oak tree roller), and Peribatodes secundaria (spruce carpet) were taken for the first time in Gästrikland. Unfortunately, several rarities in the area were not refound, for example Eilema cereola (wax-coloured footman) (threat class 3) and Prochoreutis ulfimana (whitish-streaked gnomonid moth). Both species had appeared in numbers in both 1992 and 1993 and were assessed to be resident.

The light trap has now been moved from Lågbo to Grinduga and has been running in all weathers since 1 April 1995. During 1995 we shall at last try to document the nocturnal butterfly fauna in the Trösken area as well. We hope to return next year with a series of exciting finds!

The year's most interesting butterfly finds.

Elachista regificella (magnificent wood-rush case-bearer) and Elachista quadripunctella (four-spotted wood-rush case-bearer) have been found in Gästrikland for the first time this year. During a visit to a herb-rich coniferous mixed forest at Mårtsbo on 4 June 1994, I (FYK) collected leaf-mines from Luzula pilosa (spring wood-rush); from these mines both of the above-mentioned species emerged before the end of the month. The magnificent wood-rush case-bearer is black with beautifully silvery-gleaming markings. The butterfly is recorded from most provinces up to Västerbotten in the north, so the find from Mårtsbo was not unexpected. The four-spotted wood-rush case-bearer, however, had previously only been known from two localities in Sweden; Halleberg in Västergötland and a herb-rich spruce forest with pine elements east of Dannemora Lake in Uppland. The latter locality was discovered by Johanni Itämies on 18 May 1979 (Svensson 1981). When I together with Jan-Olov Björklund visited the locality in spring 1994, we noted that the species was still present. Despite its name, the male has three and the female four white markings on each wing (see figure 1).

Of the four leaf-miner species that live in the leaves of spring wood-rush, it is only the four-spotted wood-rush case-bearer that pupates in the mine. The others leave the mine and pupate on the leaves or in the plant's surroundings.

The other two leaf-miner species that live on spring wood-rush are Elachista gleichenella (shining wood-rush case-bearer) and Biselachista trapeziella (trapezium wood-rush case-bearer). The former species is recorded up to Medelpad in the north, but reports are lacking from Värmland, Gästrikland and Hälsingland. The northernmost finds of the trapezium wood-rush case-bearer are from Uppland.

On spring wood-rush one should also search for Coleophora antennariella (wood-rush case-bearer). Like the other species in the genus Coleophora (case-bearers), the larva carries a house-like structure similar to a small caddisfly larva. The larva can be found from mid-May to the end of June. Records of the species from Gästrikland are lacking, but otherwise it is known from almost every other province up to Torne Lapland. Finally, I should mention Glyphipterix bergstraesserella (wood-rush hook-tip), whose larva mines in the stem in spring and flies as an imago from the end of May through July. The species is absent only from three provinces south of Lycksele Lapland, including Gästrikland.

Female of E. quadripunctella emerged from mines from Mårtsbo 4.VI, wingspan 12 mm. Photo Nils Ryrholm.

Coleophora lineola (stinking groundsel case-bearer) (threat class 2) has long been one of the butterfly world's most elusive "reclusive species". Before 1987 the species was only known from Kullaberg in Scania. The species was found for the first time in Uppland in 1991 (Svensson 1992) and has since been shown to occur at several locations in North Uppland, to finally in 1994 be discovered at three localities in Gästrikland: 1) Gävle, Gustavsmuren, Långhäll, 14 specimens 11.VI, 2) Forsbacka, Olsbo 27.VI, 1 specimen, 3) Oslättfors, Skarven, 3.IX, 2 specimens. (KIC)

The genus Coleophora is called in Swedish case-bearers, i.e., the larvae build cases from plant parts for protection against parasites and predators. The larva of the stinking groundsel case-bearer constructs an unusually ragged case from chewed leaf fragments from its food plant stinking groundsel (Stachys sylvatica) and is easy to identify. Larval development is probably biennial in central Sweden and the size and appearance of the case varies with age. Easiest to find are the 10-12 mm large cases of fully grown larvae, which pupate at the end of June. This type of case is usually called a Lapp case (figure 2). The larva usually lives under one of the lower leaves of the food plant. It scrapes off the cell layer on the underside of the leaf with great precision in patches. From above, fresh damage looks like semi-transparent "windows" in the leaf; these change color over time to yellowish, then to yellowish-brown and finally dark brown. The characteristic damage is a good "clue" when searching for the case (From et al 1994).

Figure 2. Larval case of stinking groundsel case-bearer (Coleophora lineola) on the underside of a leaf of the food plant. Photo Nils Ryrholm.

Pterophorus baliodactylus (royal mint plume moth) (threat class 4) lives, as is evident from its name, on Origanum vulgare. The larva lives during the summer in bitten off shoot tips (Svensson 1993). The species was previously known from several provinces from Scania in the south to Uppland in the north, but is absent from the remaining provinces bordering Gästrikland. Most known localities in Uppland are located by the Baltic coast, e.g., Rådmansö, Björn and Billudden. Some ten individuals were observed on the dry grasslands of Eggegrund during the period 30 July-5 August (KIC). Although the find is the northernmost so far in Sweden, it was not entirely unexpected (KIC).