Thursday, October 18, 2012

Punk Moth

Pale Tussock Moth Larva, Calliteara pudibunda
With its bleached-blonde mohawk, running halfway down its yellow and black body and a shocking-red spike of tail hair, the larvae of the Pale Tussock Moth (Calliteara pudibunda) is nothing if not an attentions seeker. Yet its wildly flamboyant appearance serves an important role for the caterpillar. Its long body hairs will cause irritation upon handling, and in some cases can cause severe damage to human skin (1). It is therefore avoided by most predators, a fate that the less hirsute adults are unfortunate to avoid, being food for a variety of birds. It is found throughout Europe, and is most common in the south and west of Ireland (2).
Pale Tussock Moth Larva, Calliteara pudibunda
C. pudibunda is a polyhpagous insect, feeding on a range of plants including including hops, birch, elm, flowering cherry, hazel, hornbeam, oak, poplar, pussy willow and walnut (3). Beech is a particular favourite and large numbers have been known to occur that put immense stress on commercial beech plantations. Commercial, monocultural forests such as these are remarkable only for their lack of invertebrate biodiversity due to their lack of floral diversity (4), so lack of competition is partly responsible for such outbreaks. However, the introduction of only a small number of other tree species has been shown to reduce the numbers of C. pudibunda significantly (5). Chemical volatiles emitted from Norway Spruce grown in co-culture with beech will mask the signals that attract egg laying females to the host beech trees. Such inhibition has lead to a 25% reduction in numbers of C. pudibunda in commercial forests.

  1. Backshall, 2007. Venom: Poisonous Animals in the Natural World p 49
  2. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 112
  3. Alford, 2012. Pests of Ornamental Trees, Shrubs and Flowers p. 320
  4. Christensen and Jens Emborg, 1996. Forest Ecology and Management 85 pp. 47-51
  5. Heiermann and Sch├╝tz, 2008. Forest Ecology and Management 255 p. 1161-1166

Monday, October 15, 2012

Blog Awards Ireland Finals

From left to right: Sally from Register 365, John from 21stcenturynaturalist (me), Nicola from The Sequin Cinderella and Steve from Register 365.
 A great night was had by all at the finals of the Blog Awards Ireland on Saturday the 13th last in the Osprey Hotel in Naas. Unfortunately 21stcenturynaturalist didn't take home any prizes, but the Science/Education awards went to the truly excellent Science Calling!, a most deserved winner. Congratulations to Maria Delaney on a blog that always excites and educates me.

Foreground, from left to right:  Nicola from The Sequin Cinderella, John from 21stcenturynaturalist (me), and Steve from Register 365.
Best Blog was awarded to Wise Words, while Best Blog Post (presented by the wonderful people at Register 365) went to Head Rambles for "A friendship of a lifetime". A full list of winners is available here.

Wednesday, October 10, 2012

Oxtongue in the City

Bristly Oxtongue, Picris echioides
Urban, and for that matter suburban, landscapes are often thought of as ever changing, ever moving. The commonly held opinion is that building works, cleaning and development in such areas make dynamic habitats that only the most adaptable and durable organisms can make anything close to a permanent home in. Rural habitats, which seem to experience less human interference other than agriculture, should be far more suitable for a larger range of organisms. And generally these two statements can be held to be broadly true. However, as always, there are a few delightful anomalies.
Bristly Oxtongue, Picris echioides
Bristly Oxtongue (Picris echioides) is a large and often quite branched annual or biennial of dry, disturbed ground (1). A common plant in southern England and Wales (2), it is of rare and local occurence in Ireland, being found only with any frequency in the South and South-East (1), and is considered to be nationally rare (3). Such low frequency may be explained by its status as an introduced species, being a native of the Mediterranean (4). P. echioides certainly earns its common name, Bristly Oxtongue as it is is covered in bristles arising from small white blisters all over the plant. In the past the leaves were boiled and eaten (2), possible for medical reasons as there is anecdotal evidence that it has an effect on stomach complaints (5). There may be some truth in this, as the aerial parts of the plant contains sesquiterpene lactones, some of which are seemingly unique to P. echioides (6). Its flowers, which from a distance resemble a number of other yellow Asteracea, reveal upon inspection the most wonderfully delicate sepals.
Bristly Oxtongue, Picris echioides
As it is such a scarce plant, it was with great surprise that I received most welcome correspondnace from one Mr. Pat Dunne of Cork city outlining not one, but two locations for this flower in the city. The first is on the docks of the river Lee, near to the city center. At once this area was a very busy access point for the various industries within the city, but with their disappearance or relocation the docks have become less used and this undisturbed habitat has seemingly proved ideal for P. echioides. Similarly, the second site (located in the city suburb of Ballyphehane) is a small section of waste ground in a now disused factory. While this site was in the past tended when the factory was operational, this no longer seems to be the case, which is, again, a boon for the plant. So while cities as a whole may be never ceasing monuments to progress, there are parts of them that remain refreshingly static and a refuge for wonderful organisms.

  1. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 252
  2. Philips, 1977. Wild Flowers of Britain p. 94
  3. O'Mahony, 2009. Wild Flowers of Cork City and County p. 73
  4. Preston et al., 2002. New Atlas of the British and Irish Flora p. 928
  5. Hooper, 1817. A New Medical Dictionary p. 629
  6. Marco et al., 1992. Phytochemistry 31 pp. 2163-2164

Tuesday, October 2, 2012

A Sighting of the Kidney Spotted Ladybird from Cork

Kidney Spotted Ladybird, Chilocorus renipustulatus
Ireland is home to 18 species of ladybirds, 15 of which are considered resident here (1). All of these species are also present in Britain along with 8 more (2), so it is therefore feasible to think that some of these 'extra' species may appear from time to time in Ireland as migrants. Nonetheless, I was still quite surprised to see an individual Kidney Spotted Ladybird (Chilocorus renipustulatus) on branch of some low growing willow in an unused quarry about 18 km from Cork city center on the 19th of September last. C. renipustulatus is not recorded as being present in Ireland, even though it is of common occurence in England (though less so in Wales and very rare in Scotland). 

Kidney Spotted Ladybird, Chilocorus renipustulatus
The ladybird possessed the characteristic domed elytra which were rimmed at their edges and demonstrated defensive behaviour typical of C. renipustulatus, namely clamping tightly against the surface of the branch it had been moving along. The site at which the ladybird was spotted is quite close to a large ferry port, which may account for its presence there. It may also, however, be a symptom of global warming that has lead to an increase in the numbers of species of dragonfly found in Ireland.

Kidney Spotted Ladybird, Chilocorus renipustulatus

Monday, October 1, 2012

A Flying Swimmer

Rhantus sp. Predatory Diving Beetle
A wet, wet, wet summer has given way to a pleasingly dry Autumn here in Ireland, with some of the southern counties experiencing their driest September in 26 years. This has lead to some water bodies which remained swollen throughout the year to finally experience something of a drought. Some of the more temporary examples have began to dry up and with this disappearing of certain bodies, so the predatory diving beetles, the Dytiscidae, take to the wing in search of new hunting grounds. Voracious hunters, they are found in a variety of fresh water habitats such as streams, ditches, canals and lakes, although usually in shallow water (1). Their prey are quite varied, consisting of a wide number of invertebrate larvae as well as tadpoles and worm species (2), and are excellent swimmers with large back legs perfectly adapted to pursue these prey in the water. These are lined with hairs that spread out when the leg is drawn back (in a rowing motion) and then lie flat when the leg is pushed forward, reducing drag (3). Drag is further reduced by the shape of the of the beetle's body which is streamlined for rapid movement through the water. This is tempered somewhat with the need for stability, giving Dytiscids excellent maneuverability.
Rhantus sp. Predatory Beetle
Its something of a shock therefore to see these masters of the waterways barreling through the air with all the grace of a carelessly tossed stone. Moving to new territories, Dytiscids fly with a refreshing directness, generally only halted by the water they come seeking (the individual pictured just managed to avoid me on its approach flight). The fact that many species are of considerable size (up to 4 cm long) makes seeing them a little alarming. This propensity towards large size is linked to reduction of drag in the water, with larger bodies animals experiencing much less drag than their smaller relatives (3). Ireland is home to quite a number of Dytiscidae, with 86 species being recorded here (4).

  1. McGavin, 2005. Insects and Spiders of Britain and Europe pp. 86-87
  2. Aditya and Saha, 2006. Limnologica - Ecology and Management of Inland Waters 36 pp. 251-257
  3. Nachtigall, 2009. In Encyclopedia of Insects pp. 972-975
  4. Ferriss et al., 2009. Irish Biodiversity: a taxonomic inventory of fauna p. 98