Fresh Holly blue shows its tongue

July is peak time for butterflies. What up to mid June seemed like a poor butterfly year is gearing up to a great one. Just today I watched 8 species locally. The most striking of them was this freshly emerged Holly Blue male. It is the first individual of the second generation I see this year. It basked in the morning sun in a front garden, and - unusually for this species - it sat with wings fully open for a while. Once warm, the butterfly closed its wings and fluttered onto another perch and stretched its tongue.

A more usual sitting posture for a Holly Blue, with closed wings

The butterfly with its short tongue stretched

Tongue length in butterflies is correlated with body length, so it is not surprising Lycaenids, the family to which the Holly Blue belongs, being small butterflies, have short tongues, around 8 mm. Whites and Brimstone and the Nymphalids have longer tongues, around 15 mm. For their length, some moths (such as the Hummingbird Hawkmoth) have very long tongues, 28 mm. The following table from Pollination and Floral Ecology by Pat Willmer illustrates the length differences between some butterflies and moths.

Tongue length determines the maximum depth of a flower corolla that a butterfly can take nectar from. Short tongued species prefer shallow flowers, often composite ones like brambles, tansy, hemp agrimony or dandelions.

Emerging harlequin ladybird

I collected 50 ladybird pupae (above) a couple of weeks ago. The idea was to wait and see what emerged from them to send records to the Ladybird Parasite Survey. After 6 days, 46 Harlequins had emerged, and from 2 of the remaining some tiny maggots of the parasitic phorid fly Phalacrotophora. Having so many ladybirds emerging at home meant I had a good chance to catch one of them emerging, something I had never seen before. I saw two, one of them almost right from the beginning, and this series of photos documents it. The whole process took about 10 minutes. In the next shot, the ladybird has broken the pupal skin and the pupal buds containing both pairs of wings are erect.

...she finally walks out. 

The ladybird then waits next to its pupal skin until she has hardened a bit and extends her wings, which are still yellow. You can see how the ladybird gets her spots in this post.

Darting Small skippers

A grassy area in the little wildlife garden near where I live is managed like a meadow, cut once a year. The grass is long and lush now, peppered with a range of wildfowers. One of the insects that benefits from this arrangement is the Small Skipper, Thymelicus sylvestris. The males of this golden brown, little butterfly dart around the meadow, stopping to feed or sunny themselves occassionally. The larval food plant of this species is Yorkshire Fog, a common rough grass. The adults emerge in mid June and fly in a single generation until August. They like to feed on clovers, bird's foot trefoil, restarrows, knapweeds, thistles, brambles and hawkbits. This is another butterfly species thought to have benefited from recent climate warming in the U.K. It now inhabits most of England and Wales, with its range having moved north about 100 km in the last 25 years.

A male, the same individual as above, resting on Bird's Foot trefoil. Male skippers can be distinguished from females by their "sex-brand", a dark like in the middle of their forewings.

Brown-Lipped Snails

The Brown-lipped or Grove snail, Cepaea nemoralis has received a lot of attention by evolutionary biologists for more than a century, due to their strikingly variable shell colour - what is called colour polymorphism. In the decades of the middle of the last century it was a very popular research organism. The shiny shell can be yellow, pink or brown. Over each of these background colours there can be no bands, one band or five bands, and the bands can also be fused and be of variable width. The snail above, which we found yesterday feeding on the fallen leaves on the garden path, is a yellow/one banded one. This polymorphism happens within the same population, but what puzzled biologists was the occurrence of sharp changes in the frequency of colour forms from one population to the next, and these differences seem to persist with time. This phenomenon was called "area effects". Many explanations have been proposed through the years to explain how the polymorphism is maintained and how area effects come to be, from differential predation (especially by song thrushes), adaptation to microhabitat, or other forms of selection to chance effects due to colonization after the glaciations, genetic linkage, dispersal between populations, etc. Many of these factors are not mutually exclusive and seem to have different importance depending on the population.
 We found the shells below in the beach in Spurn Head a few years ago, all in a small area. They are a bit bleached by the sun, but you can see yellow and pink snails and three types of banding patterns.

The Brown Lipped snail can be found from dunes to roadsides, gardens and closed woodland. It can live up to 8 years old. They prefer to feed on dead vegetation than fresh, and on average, only 9% of its diet is fresh vegetation, although this percentage can increase during dry spells.

References
Cain AJ, & Sheppard PM (1954). Natural Selection in Cepaea. Genetics, 39 (1), 89-116 PMID: 17247470
Davison, A., & Clarke, B. (2000). History or current selection? A molecular analysis of 'area effects' in the land snail Cepaea nemoralis Proceedings of the Royal Society B: Biological Sciences, 267 (1451), 1399-1405 DOI: 10.1098/rspb.2000.1156
Paul J. Mensink & Hugh A. L. Henry (2011). Rain event influence short-term feeding preferences in the snail Cepaea nemoralis Journal of Molluscan Studies. DOI: 10.1093/mollus/eyr011

Amber Snail Puzzle

While removing an old pot containing a lot of grass and a dead Agapanthus, next to a rainwater filled pot, I stumbled upon this little snail. I was quite surprised as initially, I thought it was a pond snail, but closer inspection revealed the tell-tale eyes-on-top-of-tentacles characteristic of land snails and slugs, while aquatic snails have their eyes at the base of their tentacles. After sifting through a Molluscs guide I found out it was a Common Amber Snail, Succinea putris. Although not aquatic, it usually lives near water or in waterlogged habitats, and it is often found on the stems of aquatic plants. It cannot retract its body completely inside the shell, and the lower pair of tentacles is vestigial. I have no idea how this snail got into our garden, but snails, despite being slow and strongly dependent on humidity, are known to disperse widely. In the Origin of the Species, Charles Darwin believed birds were the most common long range dispersal agents of snails and other aquatic animals and plants. In 1893, Harry Wallis Kew reviewed the dispersal of land and water molluscs, and discusses the evidence for external transport on the feathers of birds:

Sir C. Lyell, remarking on the wide range of Succinea putris, a land-shell which inhabits moist places on the borders of pools and streams suggested that water-fowl might have distributed its ova entangled among their feathers and it seems quite likely that ova of certain terrestrial kinds may be occasionally thus carried, either in the feathers or on the feet of birds; indeed, we have a near approach to proof of such transportal, the Rev. Canon Tristram, as we have seen, having once found ova, believed to be those of a Succinea, upon one of the feet of a mallard shot by him, on the wing, in the desert of Sahara. It is doubtful, however, whether Succinea, from the nature of the localities they often or usually inhabit, ought not, for the present purpose, to be classed with fresh-water, rather than with land-shells. Mr. Darwin suggested that the just-hatched young, possibly, might sometimes crawl upon the feet of ground-roosting birds, and thus get transported; and it certainly seems in the highest degree probable that such is the case, but, as far as I know, no observations in support of such a supposition have yet been made.

A tantalizing possibility, also first put by Darwin, is that of internal transport of organisms in the digestive tract of birds. Many bird species feed on snails, and given that no gastric juices occur in bird's crop, they can potentially survive for a while and maybe be discharged later elsewhere by the bird, or regurgitated by raptor if the bird falls prey to it. Kew stated:

 Twenty specimens of a Succinea, peculiarly packed together, and four of Pupa viuscornvi were once found by Mr. W. H. Dikes in the crop of a bearded titmouse (Parus biarmicus); all the shells, it is said, were uninjured, but it is not stated that any were observed lo be alive.

In 1968, Biggs reported on the recovery of a living Succinea putris from a pigeon's crop at least 8 h after the bird had died. Indeed, although it seems even more unlikely, some snails can survive passage through the whole digestive tract of birds provided the shell is more or less unbroken. This has recently been shown to happen to a small estuarine snail, Hydrobia ulvae, which can survive passage through the digestive tract of Shelducks, and also in some small Japanese terrestrial snails, Tornatellides boeningi a proportion of which were recovered alive in the feces of two species of terrestrial bird they had been fed to.
I don't think any of these forms of dispersal apply to the particular little snail in the above photo. Maybe it travelled on a pot plant we bought some time back in a garden centre, or, stuck to our clothes or shoes during an outing into some wetlands. Maybe, but just that any of the forms of transport Darwin and Kew discussed actually happen to snails shows you don't need wings to fly high.

References
Biggs, H. E. J. (1968). Succinea putris (L.) in a pigeon's crop Conchologist Newsletter, 24: 36.

Gerhard Cadée (2011). Hydrobia as "Jonah in the whale": shell repair after passing through the digestive tract of shelducks alive. Palaios, 26 (4), 245-249 DOI: 10.2110/palo.2010.p10-095r

Darwin, C.R. (1959) On the Origin of Species. Read the book here.
Kew, H.W. (1893) The dispersal of shells: an inquiry into the means of dispersal possessed by fresh-water and land Mollusca. K. Paul, Trench, Trübner & Co., Ltd. Read the book here.
Shinichiro Wada, Kazuto Kawakami and Satoshi Chiba (2011). Snails can survive passage through a bird's digestive system. Journal of Biogeography : doi:10.1111/j.1365-2699.2011.02559.x