Friday, May 25, 2012

Orange Tip/ Aurora Butterfly

Orange tip/ Aurora
Anthocharis cardamines

The Orange Tip flies from late April until late June and overwinters as a cocoon in low vegetation. It is named Orange tip because of the male's bright orange tips to his forewings. The males are a common sight in spring flying along hedgerows and damp meadows in search of the more reclusive female which lacks the orange and is often mistaken for one of the other 'White' butterflies. The female is - while resting - recognized by its large round spot on the forewing and the grey-black pointed forewing. Both sexes have upon the underside a moss-green marbling, which actually consists of a mix of yellow, black, grey and white scales. The male is able to hide his orange tips by tucking the forewings behind the hindwings at rest.

The wing span is 37-47 mm. The middle spot of the forewing varies in size and the border between the male's orange and white wing colour can differ, relative to the middle spot.

The flight is lively and jumpy. The females often rest for a long time in the vegetation, while the males patrol the terrain and only sit briefly on the plants or suck nectare.

The Orange tip is found across Europe, and eastwards into temperate Asia as far as Japan. The past 30 years has seen a rapid increase in the range of the Orange Tip in the UK, particularly in Scotland and Ireland, probably in response to climate change.

Orange tip, underside.

The habitats are flowery and often moist places with crucifers, like damp pastures and meadows. The Orange tip also lives in more dry pastures, along forest roads and glades and in residential districts - and along riverbanks, ditches, fens, country lanes. 

Both sexes are attracted especially to cruciferous where the female later place the eggs. The caterpillar's fodderplants are siliques from the Cuckoo flower (Cardamines pratensis), Garlic mustard (Alliaria petiolata),  Mouse-ear cress (Arabidopsis thaliana), Rock cress (Arabis), Tower cress, (Turritis glabra) and many other cruciferous.

The eggs are white to begin with but change to a bright orange after a few days before darkening off just before hatching. Because the larvae feed almost exclusively on the flowers and developing seedpods there is rarely enough food to support more than one larva per plant. If two larvae meet one will often be eaten by the other to eliminate its competitor. Newly hatched larvae will also eat unhatched eggs for the same reason. To stop eggs from being laid on plants already laid on the female leaves a pheromone to deter future females from laying.

Pupation occurs in early summer in scrubby vegetation near the foodplant, where they stay to emerge the following spring. Recent research suggests that the emergence of the butterfly may be delayed for as much as two years, thus insuring the species against unfavourable conditions in a given season.

In Denmark:
The Orange Tip (DK: Aurora)  is spread and few in numbers in West Jutland, but else widespread and common in the rest of the country. The species have spread and been more common in many places during the latest years because of the nitrate-tolerant Garlic mustard, which has replaced the Cuckoo flower as the most important host plant. .

Source: Michael Stoltze, Dagsommerfugle i Danmark, Gyldendal 1998., 2012.

photo Egtved, 9. May 2009: grethe bachmann
photo Skaade May 1999: stig bachmann nielsen, 

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