robpartridge

[robpartridge]

Thanks, Vince - I hadn't considered that possibility but I know that it happens often. Do they happen to choose the same leaves in the perfect situation or deliberately lay where others have? Perhaps there are benefits later on in being part of super-sized groups of larvae... I've no idea, having only a Biology O level!

Rob

[Vince Massimo]

Hi Rob,

I'm not entirely sure as to all the factors that dictate why a particular leaf is chosen out of so many. All I know is that it can take quite a long time . It is entirely possible that the leaf was attractive to the second female for the same reason it was chosen by the first individual, but the existence of eggs already on that leaf may have also been a factor. This also happens in several other species (Peacock and March Fritillary) where safety in numbers and "group basking" are advantageous to the larvae. We have also seen mixed egglaying this week, with an image being posted by "essexbuzzard" of a Small Tortoiseshell and Peacock ovipositing on the same leaf at the same time. As long as there is enough of the food plant, this will benefit both species.

I also have Biology O-Level

Vince

[Mikhail]

Sometimes two females use the same leaf at the same time. These were seen in Reading in the late 80s or early 90s.

I don't have Biology O level.

M.

[robpartridge]

Mikhail, even though you are not as well qualified as us, we can make you an honorary member after providing such an interesting picture! Seriously, there has to be a sound ecological reason for such behaviour. Obviously the female STs can detect tiny differences between the leaves but my hunch is that there is some advantage in being among larger groups of larvae. Fascinating.

Rob

[Lee Hurrell]

What a wonderful report, photos and observation. Fascinating stuff.

I did GCSEs rather than O-Levels, but I equally do not have one in Biology

Best wishes

Lee

[robpartridge]

Thanks, Lee. I wonder whether there is any bias towards science in the educational qualifications of members here... As butterflies have as much aesthetic appeal as any form of wildlife known to man, perhaps not. In that, sense as in several others, they seem to cross all boundaries,

Rob

[William]

I've heard similar stuff about Marsh Fritillaries, and I think Pete posted a photo on his pd with 3 females laying on the same leaf. I believe that the larger surface area that large numbers of larvae provides enables them to heat up more efficiently - not that that should be a problem with the lovely weather we're having

[robpartridge]

Hello William,

the warming up theory makes good sense. However, if it is the case, I'm intrigued that the first female to lay is pioneering the leaf and taking more risk; the second and third less so because the first brood is already in place ready to warm theirs up! I wonder if that behaviour is genetically determined - whether some females are programmed to seek other clutches rather than empty leaves...

Rob

[Pete Eeles]

Last year, I wrote an article for the Entomologist's Record and Journal of Variation, having observed something similar in the Marsh Fritillary. After liaising with Jeremy Thomas, Matthew Oates and Ken Willmott, I wrote the following based on their, and my, observations:

On the face of it, the chances of the same leaf being used among the thousands of leaves available would appear to be extremely small and so I decided to look a little more into this phenomenon, and my thanks to Jeremy Thomas, Matthew Oates and Ken Willmott for their own observations and thoughts. While egg batches of several species are often found together, such as those of Large White Pieris brassicae, I was most interested in similar observations with respect to the Marsh Fritillary and other nymphalids.

Matthew Oates has seen this behaviour in Marsh Fritillary on several occasions and not just in years when the butterfly is abundant (pers. comm.). He has also seen this behaviour in Small Tortoiseshell Aglais urticae and Peacock Inachis io. Jeremy Thomas has come across this behaviour in Glanville Fritillary Melitaea cinxia and Small Tortoiseshell, as mentioned in The Butterflies of Britain and Ireland (Thomas and Lewington, 2010, 2nd edition) and also mentioned that a newer egg batch is occasionally laid on top of an older batch (pers. comm.). Ken Willmott has also seen this behaviour in Small Tortoiseshell, Peacock and Marsh Fritillary (pers. comm.).

All of those corresponded with ruled out pure coincidence as an explanation for this behaviour.

The plant being in a favoured position for the site, possibly based on a local microclimate, is considered to provide part of the explanation since, like most butterflies, female Marsh Fritillary select a surprisingly small subset of available foodplants for oviposition, choosing those growing in optimum conditions for their young.

A deliberate strategy of co-locating egg batches was also considered plausible since larvae can thermoregulate more efficiently when numbers are higher and, more convincingly, their prickly bodies are a greater deterrent to birds, mice and other predators when en masse.

If this is the case, then the ability of females to locate existing egg batches must also be explained. Ken Willmott recalled one occasion where he accidentally disturbed an ovipositing Small Tortoiseshell which then flew around and behind him before returning immediately, without searching, to the same nettle leaf to continue building the egg batch, possibly relocated using her olfactory (smell) senses.


Cheers,

- Pete

[robpartridge]

Thank you, Pete,

and no-one is going to argue with anything that lot say! The ability to locate existing batches must present to account for the apparent regularity of such events involving more than one species. I'm still intrigued by the idea that some female has to start the process off, someone has to be first. Maybe the earliest layers are the descendants of early layers, and the later ones of those females who sought out existing batches... But I'm afraid we are well beyond my Biology O level now!

Rob

[Neil Freeman]

I did 'O' levels but not in Biology

Great reports and observations Rob, and a fascinating response from Pete.

I am finding it interesting reading about the butterflies you are finding out your way in what are often narrow strips of habitat along the margins of large arable fields. It makes you wonder how many butterflies go undetected in similar habitat which seems to be often overlooked.

Cheers,

Neil.

[robpartridge]

Thanks, Neil,

as far as I know, I'm a fair drive away from any of the rarer habitat specialist species but fortunately, like you, I find the distribution and the ecology of the commoner butterflies in the intensively farmed landscape quite interesting. Studying a local patch is more fulfilling for me than burning up yet more fossil fuels to visit well-known sites but I have no problem with those who choose to do that!

I have a birding friend who has recorded his local patch, the parish next to mine, and its environs for thirty years; his list is frankly astounding but it's all due to his persistence, skill and knowledge. I suspect the same could be true to a lesser extent for butterflies. Extraordinary things do turn up. In 2007, I think, a new teacher at the school where I worked who did not know of my interest, watched a Camberwell Beauty in an assembly hall for a few minutes before releasing it out of the window - I was in a classroom about 30 yards away! And a year or two before that another birder in Chatteris took a picture of an unfamiliar species on his buddleia which turned out to be the Queen of Spain...

One day! But in the meantime there is still plenty to learn about the rest,

Rob

[MikeOxon]

To put in my 2p worth - on the basis of no directly relevant qualifications - I think we should take account of the well-developed senses of smell and taste in Lepidoptera. For example, we know the importance of pheromones, especially in the case of moths, and of the presence of scent scale on the wings of many male butterflies We also know that these insects 'taste' with their feet, as well as having sensors on their antennae.

I have watched a brown hairstreak female walking very carefully over a number of different leaves before deciding where to roost for the night and suspect that she was using her battery of sensors to find one that would offer the best camouflage protection.

I suspect that a female similarly 'tastes' and 'smells' the leaves very carefully before laying, to sense those chemicals that indicate a good healthy plant that will feed her offspring well. In addition, she may possibly leave her own scent mark, deliberately or incidentally, which will act as a message to others that this is a good place to lay.

Having attracted moths by using artificial pheromones (I've attracted Clearwings in this way at Collard Hll), I have no doubt of their ability to home onto the spot within moments of the source being exposed

Six-belted Clearwing Bembecia ichneumoniformis
Collard Hill - 26th Juune 2011

Mike

[robpartridge]

Thanks, Mike - a fascinating picture of those clearwings,

Rob

[robpartridge]

A look at the forecast this morning suggested that sunshine might be unpredictable this week, so better make the best of it now. Brick Lane was sunny alright but the increasingly brisk southerly wind made photographing anything that did settle very difficult; several Peacocks were visiting dandelions, along with 2 Small Tortoiseshells. Numbers of male Orange Tips were good, with up to 4 visible together at one point but for the life of me I don’t know what they are going to lay on this year – there is very little garlic mustard showing at all.

Plenty of dandelions for the Peacocks

...But what will these lay on this year?

The cuckoo flower is in an even worse predicament locally. At the end of the lane I walked round to the banks of the Ouse washes reserve. Along 150 yards I found only four small plants struggling up through the rank grass, and on the flood meadow where this flower used to be in abundance there were none. The reason for this is clear in the photograph; horses are now stocked at heavy densities on many of our remaining grassfields, and wildflowers don’t stand a chance:

These struggle in rank grass

...but don't stand a chance against these.

Next to that meadow, sadly, is an area that two years ago was unmanaged rough grass for at least 40 years. It had some wonderful anthills and dew-ponds but last year the farmer’s son decided to make it more productive. It seems incredible that we can still be losing habitat like this:

Once rough grassland, it's more productive now

But it isn’t all bad news. I’ve never seen the nettles looking better and the number of Small Tortoiseshells and Peacocks laying should make for a bumper summer, weather and parasites permitting. Back on the wash banks, the wind was blowing strongly and the tortoiseshell I photographed could barely hang on to his dandelion. I searched for my first Small Heath or Small Copper of the year but without any luck. Tucked away in the Gault Holes, I found another swan's nest.

They could barely hang on in the wind

Tucked away

Back on the lane I had a male Large White fly by, and also a Small one on ground ivy, but the commonest white was the Green-veined, as usual here. I am becoming increasingly puzzled by what they eat as caterpillars, in view of what I said earlier about foodplants – I’m going to make the effort to find out. One male Brimstone appeared but no Speckled Woods yet, since the farmer (yes, the same one) eliminated the southern hedge. Close to the car, no stickleback today but a nice queen wasp basking – species, anyone? – and heaps of rabbit fur. I’ve spent most of my lifetime in the country but never actually seen them fighting.

No Speckled Woods

Species, anyone?

So, no good pictures, thanks to the wind, but plenty to see and think about. I saved the most moving picture until last. A fluttering in the grass at the bottom of the bank led to me finding this Small T sheltering from the wind but still enjoying the sunshine, to the last. I sat and watched him for several minutes - it seemed only right:

I sat and watched him for several minutes...