The Brimstone Butterfly
Brimstone butterflies are a medium-large butterfly with leaf shaped wings. The males are lemon-yellow whilst the females are a very pale green. Both have a small orange spot on each wing. In April or May they lay their eggs on buckthorn or alder buckthorn shrubs. They are laid on their own which is unusual as most butterflies lay their eggs in clusters. The caterpillars emerge two weeks later and spend most of the next four weeks eating and shedding their skin – four times in all. To pupate they move away from their food source forming their chrysalis, which looks like a curled leaf, on a nearby plant. It takes about two weeks for the caterpillars to transform into butterflies so that the adults emerge in late July or early August. They all then go on a feeding frenzy building up their fat reserves ready for winter. By late September they have disappeared, hibernating amongst ivy, bramble or holly leaves. The following March they begin to emerge on warm, sunny days and it is now that the males start looking for a female to mate with. They have the longest adult lifespan of any UK butterfly, nine to ten months, so even though they only have one brood annually they can be seen for most of the year. They are widespread across most of the UK and can be found in almost any habitat from woods and chalk downlands to gardens.
Did You Know?
- Brimstone butterflies have a very long proboscis enabling them to take nectar from plants such as teasels and runner bean flowers which are beyond the reach of other butterflies.
- The green caterpillars can adjust their colour to match the leaves they are feeding on.
- They are strong flyers and especially in the spring may travel some distance in search of a mate.
- They are the first butterflies to appear after the winter.
- In spring they feed on the nectar from dandelions, primroses, cowslips, bugle and bluebells.