By Jess Price
August is a great time to go looking for the adonis blue - one of Britain’s rarest and most beautiful butterflies. The adonis blue can be seen on chalk downland in areas where horseshoe vetch, the food plant of its caterpillar, is found. Look for colonies on the warm south facing South Downs slopes between Beachy Head and the river Arun. As with other grassland species, ploughing and lack of grazing has resulted in a decline in populations.
In West Sussex, Mill Hill at Shoreham-by-Sea is a good site to see them and there are two chances to view this stunning insect every year. The first brood emerges in mid-May until the end of June, with the second brood appearing for a few short weeks in August.
The male is easy to spot with its brilliant sky blue wings and can be found flying low over vegetation, seeking out the less-conspicuous females which are a rich chocolate brown in colour, with only hints of blue. Both male and female adonis blues have black lines on their wings extending into the white fringes.
The slug-shaped caterpillars are green with yellow stripes running along the length of their bodies. Unlike some caterpillars, the larva of the adonis blue feeds by day. They have a symbiotic relationship with ants which feed on the secretions from special honey glands found on the caterpillar’s body. In return, the ants protect the caterpillars from parasites and other predators and have been known to bury the larva in a chamber in the earth, where they continue to ‘milk’ it for secretions into its pupal stage. They will continue to protect the pupa until the adult butterfly is able to emerge out of the soil.
The adonis blue butterfly has had a major decline over the last 200 years and is protected from sale under the Wildlife and Countryside Act 1981. However concerted conservation efforts have seen a slight recovery of some populations in recent years.
So, next time you are walking on the downs and the sun is shining, keep a look out for these stunning insects. For further information about wildlife and nature reserves in your area please go to: www.sussexwildlifetrust.org.uk/visit