This summer is a perfect time to go in search of Royalty. Not Charles, Camilla, William or Catherine, but our very own Emperor – the Purple Emperor, one of our largest, most spectacular but elusive butterflies. Until recent times this splendid insect was largely unknown in our counties but survey work by Butterfly Conservation has discovered it breeding in a number of woodlands where sallow willow, the larval food plant are plentiful. 

The Purple Emperor is a large brown butterfly and the male’s upper wings shine an amazing iridescent blue or deep purple in sunlight. In early July males joust for territory around tall Oaks or Ash trees in the highest part of chosen woods. However, searching for displaying males is a hit and miss affair and for the most part leads to a stiff neck from all that peering heavenward.  Fortunately for butterfly watchers, the male Emperor has a rather disdainful habit (to us) of feeding on animal droppings, including that left behind by dogs. They will also take salts from puddles and mud and any type of rotting flesh. Their descent to ground level usually takes place in the morning and whilst feeding, the butterflies can be approached very closely. 

In Hertfordshire, the Trust’s Balls Wood Nature Reserve in early July is a good place to go in search of Purple Emperors. Get there on a warm day between 10am and 11am and pick a good vantage point overlooking a sunny glade and then just wait… If you’re lucky you will be rewarded with views of one of our most beautiful butterflies. Just try to forget about what it’s eating!

After feeding, males fly off to a high point in the wood where they will settle in the top of a tree looking out for a female to woo. If another male comes close, he will be chased off with some aggression and aerial battles may ensue if rivals are equally matched. 

Female Purple Emperors lack the colour of males and only when ready to mate will they approach the high spots in the wood where the males gather. After mating they go in search of sallows, on which eggs are laid directly onto the upperside of leaves. After about 10 days the caterpillar emerges and feeds prior to hibernating in November. They start feeding again in spring before forming a chrysalis in June where the metamorphosis into the adult takes place.

The other top places to search for Purple Emperors are Heartwood Forest near Sandridge and Whippendell Woods near Watford.

Do share your butterfly photos and sightings with us this on our social media channels or email us at media@hmwt.org