Our volunteer Trevor Grange is on butterfly transect duty this week – butterfly transect weeks start on Wednesdays this year, and he decided to give it a go on Wednesday 3rd June.

What are butterfly transects?

It was a bit overcast but with bright spells, warm and not too windy in the morning, so conditions were good. Trevor phoned me up before he’d got half way round as he had just seen his first marbled white butterfly of the year!

This is a lovely species which is still a treat to see, we have been seeing them every year on our transects since 2012, with an odd sighting a couple of years before.

It is a species that has colonised East Anglia in the last decade, spreading north as the climate warms, but despite being around for a decade or so, it still seems a surprise and delight to see one, and numbers have only started to build up in the last couple of years, with annual totals reaching double figures in just the last two years.

What made it all the more surprising for Trevor was the early date. This is ‘week 10’ of the butterfly transect year, our previous earliest were in week 12 -  Trevor was also lucky to get the first of the transect count on 19th June 2019.

The sudden drop in temperatures might reduce the rate of emergence for the next few days and weeks, but this early emergence is clearly related to the hot dry spring so far.

Although the name is ‘Marbled White’ this species is actually a brown species of butterfly. The browns include meadow brown, xpeckled wood and many others, which generally feed on plants in the graminae (grass) family.

The whites are the familiar cabbage-patch butterflies, and also include the orange tip and other non-pest species, their caterpillars generally feed on plants in the brassica (cabbage) or leguminacea (pea) families.

Marbled whites are white with black or dark brown patches in a marbled pattern. They have a particularly graceful flight over flowery meadows. The females lay eggs while flying over tall grasses, and the eggs hatch in spring to start feeding on the young grass growth.

This is the first species that overwinters as an egg to be seen this year on Lark Rise this year.

Dr Vince Lea
Head of Wildlife Monitoring 

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