Black-veined White Aporia crataegi (Linnaeus, 1758) — Gästrikland's Provincial Insect

The hawthorn butterfly is a social butterfly that likes to sit in large flocks on damp ground where it seeks water and mineral salts. This behaviour is common among tropical butterflies but occurs in our region almost exclusively in the hawthorn butterfly and a few blues. The population varies greatly from year to year. Over a period of 4-5 years it can be almost completely absent, only to appear fairly commonly again over several years. The English name "Black-veined White" describes excellently how the butterfly looks. However, only the male has black wing veins. The female has brown wing veins. The hawthorn butterfly is, together with the cabbage butterfly, the largest of our so-called "white butterflies", but unlike the latter is a typical sedentary butterfly that in our region does not fly long distances. Apart from its black or brown wing veins, the butterfly is completely white on both sides of the wings. Towards the end of the flight season, however, the females' wings often become worn from their habit of repeatedly rubbing their wings against those of willing males during mating. Her wings can then become nearly transparent, especially towards the outer edges. Apart from flocks on the ground, one usually sees it flying alone through sparse mixed woodland, along forest edges, forest roads, and the increasingly important biotope of power line clearings.

The genus Aporia is primarily an Asian genus which, together with its sister genus Metaporia, contains around 50 species, of which Europe and Sweden have only one, our beautiful hawthorn butterfly. The genus name Aporia is a Greek word referring to the lack of markings on the wings, while the species name crataegi refers to the host plant hawthorn. The cone-shaped red-yellow eggs, with 13 longitudinal ribs, are laid at low height in groups of 50 to 150, usually on the underside of the host plants, which include rowan, hawthorn, elm, cherry, wild apple and similar trees. After hatching, the larva does not eat much but overwinters as a small larva, arranged in columns in a nest made of spun leaves. In spring they then disperse in small groups. The larvae now develop rapidly into very beautiful reddish-brown creatures with two orange-red bands along the back. However, one should exercise some caution as they both smell foul and are equipped with toxic hairs. The adult, now grey, larva up to 4 cm long, pupates during May-June in a light yellow-green girdle pupa with strong black markings. The pupal stage lasts just over 2 weeks before emergence occurs. When the wings are fully developed but before the first flight, the butterfly expels all waste products from the pupal stage in the form of a powerful stream. It sometimes happens that this very red secretion lands on the wings, which then become partially red-coloured in these individuals.

In Gävleborg County, the adult butterfly usually flies from the end of June to mid-July, while further south it can begin flying as early as May. The hawthorn butterfly is locally fairly common up to southern Norrland. In Gävleborg County it has one of its strongest populations in the country with a very vigorous population in the power line clearings in the Grinduga - Trösken area southeast of Gävle. However, it is encountered from time to time in its characteristic mass-sittings along wet forest roads throughout Gävleborg County. This has been the primary reason why the hawthorn butterfly was chosen as Gävleborg County's provincial insect. Göran Sjöberg 1999. (text & photo)