I've always been intrigued to know how butterflies manage to deal with some of the problems associated with prolonged periods of atrocious weather, such as that experienced here in Sussex over the last few weeks. Brown Hairstreaks are usually notoriously fussy about the weather conditions under which they're prepared to go about their business - but what if they have no choice? In a 'normal' August they generally won't go egg-laying unless it's warm and sunny, and mostly between 11am and 3pm. In an average summer they will happily sit around doing nothing for a few days, until the weather dictates that every other species is on the wing, and you can hear the 'song' of grasshoppers and crickets.
At least locally, conditions have been unsuitable for oviposition since 16th August. A brief spell of milky sunshine on the 18th saw them starting to move around the canopy, but they weren't tempted to descend and lay eggs. After a further five days of rain, high winds and zero sunshine the females must have been fit to burst, and the necessity to get rid of some eggs must have become the over-riding factor in their behaviour.
On Tuesday (23rd August) I joined Colin Knight at Steyning Rifle Range, in conditions only marginally better than of late. Nothing else was flying - not even Meadow Browns, which remained cowering in the grass. However, with a brief thinning of the cloud and a modest rise in temperature, a couple of female Brown Hairstreaks were busy laying eggs - very busy! On a warm and sunny day they are usually very particular about selecting an oviposition site, constantly testing and rejecting numerous candidates before finally popping one out. This might take 15 minutes of indecision between lays, following many prolonged 'tests' on a number of blackthorn suckers. However, on Tuesday we watched a female crawl straight to the base of a sucker and squeeze out four eggs on the trot, in less than five minutes. Two were laid side-by-side and the others just above and below (one just out-of-frame in the image below). Five minutes later and a heavy shower brought the day's action to an end.
In previous years I've noticed how extended spells of particularly bad weather can influence the egg batch size in Duke of Burgundy. Whereas the 'norm' might be anything between one and three, after one particularly lengthy period of 'no fly' weather I found two batches of eight and one of ten eggs! Never a good idea to have 'all your eggs in one basket', but it seems that butterflies are quite capable of changing their behaviour when 'needs must'. Which is why of course, that our butterflies are so adept at surviving our b****y awful summers!
Hulmes left right and centre.
