Large white butterfly - Pieris brassicae - Kálskjanni - Hvít fiðrildi - Skordýr

Large white butterfly - Cabbage White - Pieris brassicae - Kálfiðrildi - Kálskjanni - Hvítskjanni - Hvítt kálfiðrildi flögrar um - Af skjannaætt (Pieridae) eru til 48 tegundir í Evrópu. Þar af tilheyra átta ættkvíslinni Pieris. Kálskjanni Pieris brassicae er stærstur tegundanna. The large white is a strong flier and the British population is reinforced in most years by migrations from the continent. The Large White is one of two species (the other being the Small White) that can claim the title of "Cabbage White" that is the bane of allotment holders all over the British Isles. The larva of this species can reach pest proportions, and decimate cabbages to the point that they become mere skeletons of their former selves. Cabbage white caterpillars leave their food plants when ready to pupate and usually attach themselves to a vertical surface such as a fence or wall with a silk girdle before their final skin shed. The female is distinguished from the male by the presence of 2 black spots, together with a black dash, on the forewing upperside. This is one of the most widespread species found in the England.

Flestir sem ferðast hafa til nágrannalandanna kannast við stór hvít fiðrildi á flögri yfir ökrunum. Þau eru svo sannarlega augnayndi, en hins vegar ekki að sama skapi vel þokkuð af þeim sem akrana rækta. Þetta eru kálfiðrildin svokölluðu, eða skjannarnir. Lesa meira:

Engjaskjanni - Pieris rapae.
Skuggaskjanni - Pieris napi.

This species is particularly vulnerable to a parasitic ichneumon fly, Apanteles glomeratus, which deposits its eggs inside young larvae. The fly larvae feed on the insides of their host, avoiding vital organs, and, when their host is full-grown, break through the skin and pupate within yellow cocoons on or near their host. The primary larval foodplant is Crucifers (various) (Cruciferae family (various)). Nasturtium (Tropaeolum majus) and Wild Mignonette (Reseda lutea) are also used. See more:

The large white eggs appear as a pale yellow colour. They turn into a darker yellow within twenty-four hours of being oviposited. A few hours prior to hatching, they will become black in colour, and the shell will become more transparent, and the larvae will appear visible. The large white eggs hatch approximately one week after being laid and live as a group for some time. The hatching period constitutes around two to seven hours. Upon hatching, they cause a lot of damage to the host plant by eating away at and destroying the host plant. For both males and females, the wings are white with black tips on the forewings. The female also has two black spots on each forewing. The underside of each wing is a pale greenish and serves as excellent camouflage when at rest. The black markings are generally darker in the summer brood. The large white butterfly's wingspan reaches 5 to 6.5 cm on average. The large white butterfly's habitat consists of large, open spaces, as well as farms and vegetable gardens, because of the availability of its food source. Some favoured locations include walls, fences, tree trunks, and often their food plant, which is important for large white survival since they need to have access to their food source for survival. They primarily hover around these locations, which should contain both wild and cultivated crucifer, as well as oil-seed rape, cabbages, and Brussels sprouts. See more:

Large holes in the leaves of brassica crops and nasturtiums are usually the work of cabbage white caterpillars. Before an attack you may notice large numbers of white buttlerflies around your plants, as they lay eggs. These hatch into larvae which make small holes in the leaves as they start to feed on them, becoming much larger as the caterpillars start to feed more vigorously. Caterpillars also produce small brown or dark green granular deposits as they feed. See more:

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