This exceptionally early spring raises the question of how it is that the butterflies coordinate their emergence so beautifully with their food and nectaring plants. Here in Switzerland, many flowers have come into bloom a month early, and I know from reading your records that something similar is happening in Britain. The chrysalids of various blue species, in particular, that have spent the winter under stones or in soil, have responded by emerging a month early too.
Do the plants and the butterflies respond to the same environmental stimuli or do the plants (unwittingly) communicate their flowering to the chrysalids? One of my students suggested the butterflies could smell the nectar. It seems improbable to me, but are there other chemical changes going on that the butterflies can respond to?
I would love to know, if anyone has any information. It all seems very wonderful to me.
Guy
Synchronisation of plants and butterflies
Well my thought on this delicate subject is that all the changes are conected by climate.
If a certain plant needs sunlight/heat to grow then when the first sunlight is around then that plant will be present.
This also applies to the butterflies of that time. ie if the blues are the first to emerge then if the sun comes in April or May the blues will always be the first along with the certain plants.
You will find that if the weather is consistant the next variety of butterflies will emerge early in time with the next variety of plant.
The time between say the blues and browns will stay the same even though it could be a few weeks earlier than the previous year.
Hope you understand my thoughts.
If a certain plant needs sunlight/heat to grow then when the first sunlight is around then that plant will be present.
This also applies to the butterflies of that time. ie if the blues are the first to emerge then if the sun comes in April or May the blues will always be the first along with the certain plants.
You will find that if the weather is consistant the next variety of butterflies will emerge early in time with the next variety of plant.
The time between say the blues and browns will stay the same even though it could be a few weeks earlier than the previous year.
Hope you understand my thoughts.
In Finland we talk about something that translates as "Heat sum". It seem to be a pretty good indicator for the time when butterflies emerge. Naturally, the critical value varies between species.
I don't remember the exact formula, but it was something like the sum of average daily temperatures, when the average is above 0 C. Probably a bit different in southern regions, but the principle may well hold.
I don't remember the exact formula, but it was something like the sum of average daily temperatures, when the average is above 0 C. Probably a bit different in southern regions, but the principle may well hold.