The migration of birds during the spring and autumn months is very apparent. Most people look forward to the arrival of the cuckoo in spring and are aware of the large gatherings of Swallows and Martins in the autumn. A phenomenon that seems to take place just before their departure to warmer climates.
However, what seems to go by almost totally un-noticed is the migration of moths and these flights can be very impressive and just as awe-inspiring as the journeys made by birds.
Take the Silver Y for example, which is probably one of the most common and well-known migrant moths to Britain. It is so named due to the prominent white “Y” shaped marking within the central area of the forewing. (see above photo)
Almost completely without notice, the Silver Y arrives in Britain from Southern Europe during our spring and summer. Then during the autumn months, some individuals make the return journey back south. A remarkable statistic about this moth is that it can match, and in some instances beat, the speed of many small migrant birds, such as warblers and flycatchers.
According to some interesting information I have read recently, the Silver Y has a habit of waiting until the wind is blowing in the general direction in which it wants to migrate. It then flies up to an altitude of around 400 meters. By doing this it gains a tremendous momentum of speed from the tail wind and in some cases, gaining a real boost from the jet stream. This technique helps the Silver Y to cover a journey of 700 kilometres in around 8 hours of flying time. Putting this into some kind of perspective, that’s like travelling the full length of the UK in a single day. For such a tiny and delicate little creature, that is some achievement.
So, during next spring and summer, keep your eyes open for a Silver Y and when you see one, give some thought to how far it may have travelled.