In the last ten days, three new species of invertebrates have been discovered in the park, photographed and identified by experts: an azure damselfly, a tent web of small eggar moth caterpillars and a brown argus butterfly.
The brown argus (Aricia agestis) is classified as a blue butterfly despite the fact that both male and female are brown. Its underwing best demonstrates its kin to the blues, and its similarity to the female of the common blue.
1, Underwing of brown argus; 2. female common blue
On calcareous grassland in southern England, the mated female lays her eggs on cranesbills. There are three well established species of cranesbills in the park: hedgerow cranesbill, meadow cranesbill and cut-leaved cranesbill. When the butterfly eggs hatch, these are the caterpillars’ food plants.
3. hedgerow cranesbill; 4. meadow cranesbill; 5. cut-leaved cranesbill
The caterpillars, from the moment they hatch and throughout the whole of their larval stage, are attended by ants; this is an association called myrmecophily. The ants protect the caterpillars from predators, particularly from parasitoid wasps, and the caterpillars reward the ants for their efforts with sugary secretions of honeydew, a high value foodstuff.
6. Brown argus caterpillar; 7 brown argus adult.
The park is becoming more biodiverse every year and we are discovering new species all the time. This year, 2020, we have already added eleven new species to our lists despite the coronavirus lockdown, which has kept all of the Countryside Team and the large majority of the Friends of Southwick Country Park at home since the end of March.
Go carefully; stay safe.
Header picture: Brown argus by Charles J Sharp (CC BY-SA 4.0) wikimedia.org
More of 2020’s new species: