Late Summer in a Wealden Wood

 August is the month when the nights definitely start to draw in and a nip in the evening air hints that autumn is not far away. Summer species of butterflies are now showing signs of age but late summer species and broods are looking fresh.

Silver-washed Fritillary (Argynnis paphia) (post-copulation)

This pair rest together for a while after mating before the male flies of and leaves the female to bask in the sun.

Common Blue (Polyommatus icarus) (female)

Whilst the Common Blue is very much at home in woodland glades, the Chalkhill Blue is most definitely a chalk downland species. However, when their populations erupt in good years, they do wander from their breeding grounds. I have seen them in wealden woods before but it still seems odd to see one flying around a marshy meadow about 5 miles from its nearest downland colony.

Chalkhill Blue (Polyommatus coridon) (male)

Small Tortoiseshell (Aglais urticae)

Painted Lady (Vanessa cardui)

Peacock (Aglais io)

Speckled Wood (Pararge aegeria) (male)

Emperor Dragonfly (Anax imperator) (male)

 

Gynandromorph

 Earlier this week, as I walked around one of my favourite Wealden woods, I encountered an extraordinary butterfly and a lifetime first for me.

As I moved slowly past some bramble beds, I noticed a slightly worn looking Silver-washed Fritillary (Argynnis paphia) nectaring on bramble flowers. I barely took much notice of it but as it started moving around the blossom, its wings on either side were clearly different shades. I could see that this was a very special butterfly.

This paphia was gynandrous, meaning that its markings were displaying both male and female traits. More specifically it was a bilateral gynandromorph meaning that it is exactly half  male and half female, with the dividing line running down the centre of its body.

Gynandromorphism is an extremely rare occurrence in nature. When a sperm fertilises an egg to form a zygote, a fault can then occur during the first cell division (mitosis) whereby a sex chromosome is lost from one of the daughter cells. In the case of bilateral gynandromorphs, the continuing cell division ultimately produces a butterfly that is half male and half female.

Silver-washed Fritillary (Argynnis paphia)

Bilateral gynandromorph (male on left, female on right)