Saturday, 24 October 2015

Emergence …

Long-tailed Blue (Lampides boeticus)

Saturday, 19th September saw the first of the 2015, Sussex born Long-tailed Blues’ emerge, with two females, found by Neil Hulme at Newhaven Tidemills. Following a lengthy break in proceedings, a pristine male was discovered at Beeding Cement Works, also by Neil, on Thursday, 8th October. Despite a rather slow start things still looked promising, as in 2013, for a mid-late October emergence.

However, by Monday, 12th October the weather began to cool and, with the ever-pending threat of overnight frosts, a cold northeasterly wind set in - though the weather remained generally dry and bright. High pressure was predicted to remain over the UK for at least ten days. Thursday, 15th October was cold and overcast with a daytime coastal high of around 12-13°C; the chilly northeasterly breeze still present. On a positive note, the frosts have stayed distant, at least to date, with overnight temperatures, on average, only dropping to around 7-8°C. Although wind chill is unlikely to stop emergence it would mean a lengthened development period and also less active adults when they finally emerged, consequently they would be much harder to locate. The presence of a hard frost would be a completely different matter!

Complete development of L. boeticus (egg to adult) can vary considerably with those individuals breeding in warmer climates being substantially quicker - as short as 28 days (Cribb, 2001) - compared with those in the cooler northern hemisphere - up to 58 days and possibly longer (D. Harris, 2015, pers. comms., 19 October; pers. obs., 2015); confirmed by a female, witnessed in the wild state, having emerged on Monday, 19th October after 22 days in the pupal stage and, with an estimated egg-laying date, some eight weeks earlier, of Saturday, 22nd August. Latitude, temperature, humidity and the nature of the seasons all undoubtedly play an important role in the development of L. boeticus. This is by no means unexpected nor is it exclusive to boeticus. For example, it is believed that some slow-developing larvae of the Mountain Ringlet (Erebia epiphron) may spend two years in the larval stage, usually the result of a late spring and a short summer period.

Weatherwise, Tuesday, 20th October was the day we all been waiting for - blue sky, sunshine, highs of 15°C and, finally, the cold northeasterly wind had abated. However, this only lasted for a day as Wednesday, 21st was wet and windy. Despite dull and overcast conditions, a freshly emerged female (pictured above) was discovered at Beeding Cement Works on Friday, 23rd October. I feel sure that the 2015 season is far from over and that we may still see fresh Sussex born boeticus in November …

More at:

Cribb, P. W. (2001). Breeding the British Butterflies. Edition 3. Orpington, Kent: The Amateur Entomologists' Society, 18, pp.49-50.


  1. Hi Mark. I'm fascinated by the arrival of the LTB in England. We live in the small island Kingdom of Bahrain and are the proud "owners" of a colony of LTB which returns to our garden every year. I have been trying to understand the timing of emergence, egg-laying and larval development, and some of your references will be helpful for me. The adults seem to emerge (either from pupae or from 'hiberation' immediately after the hot summer here and fly around a pea/bean-like tree here in the garden (if I send photos, do you know anyone who can identify it?). This tree lies dormant in the summer, but bursts into live again once the temperature has dropped and produces a mass of red flowers. LTB female lay their eggs on the buds and I have a garden-full of them (buds!) right now. I think what happens is that a 2nd brood emerges around Christmas and possibly a third in Feb/Mar, before the summer arrives and everything closes down. I wonder if you are aware of any scholarly works on LTB out here? Maybe I should write one! All the best. Thanks for LTB updates from November too

  2. I'm glad you have found my reports on interest. As a multivoltine species (having two or more broods or generations per year), winter survival in Britain, or indeed anywhere north of the Mediterranean region, is highly unlikely. However, in Bahrain, boeticus is most likely to be continuously brooded. I am not aware of any scholarly works outside of the UK though feel sure they would exist. I'm afraid I can't help regarding your pea/bean-like tree though suggest posting a selection of images on the UK Butterflies website - - in the hope that someone may guide you in the right direction. Throughout many parts of its range, this beautiful little butterfly is considered a pest of members of the Leguminosae (Fabaceae or bean family); hence some of its other vernacular names, the Pea Blue or Bean Butterfly. I feel sure your plant will be in this family. Good luck!