Migration Camp



Silver y

It's an amazing thought that up to 240 million moths migrate to the UK every Spring from Southern Europe or Africa.  I think it's incredible that a small bird can fly that far.  Moths and butterflies look far too flimsy to survive such a journey, but they do.  The Silver Y is one of our most common visitors:

They arrive from Souther Europe in May and can produce two to four generations each Summer.  Eggs are whitish in colour and hatch after three or four days: the caterpillars are about 3cm long and light green.  They walk by stretching the front of the body then bringing the back up to meet it because they only have two sets of prolegs instead of the usual four. They have been recorded on over 200 different types of plant so basically they eat anything!!  No wonder we see them as pests!  The pupae takes 10 - 14 days to become an adult.  They start mating almost immediately and produce eggs two to five days after emerging.  The moths live about 21 days.

Scientists have been studying their movements.  They used to think the Silver Y flew across here and died in their thousands because they couldn't survive our colder climate but the latest research has shown that the UK is in fact a very productive breeding ground.  The moths multiply in number by coming here and then retrace the routes taken by their parents in huge numbers.

Garden Carpet

 Garden Carpet is another common visitor but these prefer to fly at night.  They are the ones bashing into your lighted window after dark.  They produce two generations per year and can survive our winters in the pupae state. 

They fly between April and October.  Go check your Wallflowers and Nasturtiums for holes as the caterpillars are rather partial to the leaves!

 Here is another night flyer - an Orange Swift:

Orange Swift

This poor thing only has a few weeks to live because it doesn't have a mouth.
Its caterpillar made up for it though!  It has a voracious appetite and lives for about two years underground.  It chews up anything it can find ... your prize bulbs and tubers for example!

When you think about all those millions of moths (and butterflies) flying to the UK and producing billions of eggs to grow into billions of caterpillars it's a wonder we have any plants left!  Help is at hand though.  One young Blue Tit eats 100 caterpillars a day; a brood of ten chicks gets through 1000! Britain is home to about 3.5 million pairs of Blue Tits.  According to Butterfly Conservation Blue Tit chicks eat 35 billion caterpillars a year so we need all the migrating moths we can get!


Photographs - copyright of Andy Mason