As lepidopterists we are fortunate in the UK in having the benefit of a rich source of literature going back many generations to support and inform our many endeavours in the field. In my early days South's Colour Identification to British Butterflies was a wonderful source to aid identification of species such as Pearl and Small Pearl Bordered Fritillary not to mention High Brown versus Dark Green Fritillary. We owe a debt of gratitude to our forebears in providing us with a baseline of valuable information and data to inform our further work in the field.
To my mind understanding conservation is all about asking questions about our observations and findings. Seasonal species-specific observations and data are interesting and valuable in informing longer-term trends taking variables such as seasonal weather, habitat changes, parasitism etc into consideration.
The behaviour of arboreal butterflies have interested me for some time. Much of our established literature states that many species such as Purple, Brown and Black Hairstreaks as well as Speckled Wood and Purple Emperor feed on aphid honeydew deposited on a variety of leaf-forms e.g. blackthorn, ash and seemingly oak.
Over many years in the field I have attempted, through observation, to confirm this assumed feeding behaviour particularly in relation to Brown and Black Hairstreak and to a lesser extent the Speckled Wood.
The Brown Hairstreak is a species I am very familiar with, both in my home-county and further a-field in the UK. I have often sought out evidence of the presence of aphids, or their deposits of honeydew, on known assembly ash trees in the case of Brown Hairstreak. These observations are made simply both from close visual inspection and through touch for stickiness. To date I have never located evidence of aphids or their 'sticky' secretions on assembly trees or on blackthorn. Where have all the aphids gone?!
I have often observed individual Brown Hairstreak and on several occasions Speckled Wood butterflies using their proboscis probing on or about ash buds. Subsequent inspection of these ash-buds for evidence of a presence of aphid life-forms or honeydew have never resulted in success. My observations are made from the ground and not at canopy level.
My personal view is that these individual butterflies are indeed taking up some form of nutrient when probing these ash-buds. Is there concrete evidence that this form of nutrient is from an aphid source? Has an analysis ever been conducted to verify what nutrients might be present on these buds?
I reserve judgement on the feeding behaviour on leaves reputably 'laden with honeydew' as I have never witnessed aphids despite searching. Have aphids been witnessed on leaves by other observers? What is the source of secretions that might be present on the leaves? Is there any research results that has identified the substance?
As a mere amateur lepidopterist am I missing something? What do others observe?
Do we have a budding lepidopterist or PhD student out there with access to more scientific resources to inform this question?
On my many field trips I have many questions but few answers. Help!
Jeremy Clarkson-lore states 'Never park the love of your life under a lime tree!' Does he know something we don't?
Thought-for-the-Day or just Sailing-by?
Tom Dunbar
