Horse Chestnut Scale on a Linden Tree: a Polyphagus Insect

Horse Chestnut Scale, Pulvinaria regalis

While I have previously written on this blog that scale insects tend to be quite small, a large example has recently come to my attention. Pulvinaria regalis, or the Horse Chestnut Scale, is c. 6 mm in diameter, and the female is particularly visible this time of year when they produce a large, white, fluffy, ovisac into which up to 2,000 eggs are layed (1). Upon laying the eggs, the female dies, but remains attached to the ovisac as a protective shield. Without the ovisac, Pulvinaria regalis is excellently camouflaged against the bark of its hosts, Horse Chestnut, Linden and Elm species (its many hosts making it polyphagus), where it feeds by extraction of sap. Once the young hatch, they are easily dispersed by the wind due to their small size (2)

Horse Chestnut Scale, Pulvinaria regalis

P. regalis is thought to be of asian origin, and was first recorded in Europe in 1968 (2). The first record for Ireland was as recent as 2000 on a horse chestnut tree in Dublin, and the authors speculated then that P. regalis may spread throughout the country (3). This has proved to be the case as shown by this sighting in Cork city.

Horse Chestnut Scale, Pulvinaria regalis on Linden Tree

P. regalis is a particularly urban insect in Ireland, and Britain, where its host plants are not native (2). It rarely causes significant damage to trees, proving to be just rather unsightly.

References:

1. Speight and Nicol, 1985. Antenna 9 pp. 175–178
2. Speight et al., 1998. Ecology 79 pp. 1503-151
3. O'Connor and Fox, 2000. Entomologist's Gazette 51 pp. 145-146

Saint Patrick's Cabbage

Saint Patrick and Shamrock go hand in hand, like bread and butter or Laurel and Hardy. Legend has it that the saint used the three leaved Shamrock to demonstrate the Christian holy trinity, how the father, son and holy spirit could exist as one. Yet, while Saint Patrick makes numerous references to the trinity in his writings, nowhere does he mention the Shamrock (1). The association came some time after his death, most likely the co-opting of a pagan symbol into Christianity. Indeed the identity of the Shamrock is hazy to say the least, with various sources identifying it as wood sorrel, white clover and black meddick (2,3).

Flowers of Saint Patrick's Cabbage, Saxifraga spathularis

However, there is another plant that honours Ireland's patron saint, one much more deserving of the role. Saint Patrick's Cabbage is a saxifrage that bears the saints name both in its common name and its binomial moniker, Saxifraga spathularis. It is a distinctly Irish plant, being found only on the Island of Ireland as well as northwestern Spain and the mountains of north Portugal (4), where it is commonly called abelairiña. Its clusters of green leaves bear stalked pannicles of pretty white flowers that show numerous pink dots on the petals. S. spathularis has a wide tolerance to soil conditions and can be found in a variety of habitats, from exposed mountains to the shade of humid woodlands. In Ireland, it is distributed along the west coast, from Cork to Donegal, however its main base is in Kerry and West Cork. Records have been reported from Tipperary, Waterford and Wicklow, but pressure on hedge banks could be reducing its incidence (4).

Saint Patrick's Cabbage, Saxifraga spathularis

S. spathularis is closely related to another saxifrage species particular to Ireland and northern Iberia, Kidney Saxifrage (S. hirsuta). The two species can in fact hybridise to form S. x polita, which is commonly found growing in gardens as False Londonpride. Areas where S. spathularis and S. hirsuta grow in close proximity have seen an increase in the hybrid to the detriment of the populations of these two species (5).

References:

1. Edna Barth, 2001. Shamrocks, Harps, and Shillelaghs: The Story of the St. Patrick's Day Symbols pp. 146-149
2. Colgan, 1892. The Irish Naturalist 1 pp. 95-97
3. Frazer, 1894. The Journal of the Royal Society of Antiquaries of Ireland 4 pp. 132-135
4. O'Mahony, 2009. Wildflowers of Cork City and County pp. 128-130
5. O'Mahnoy, 1994. Irish Botanical News 4 pp. 17-19

The Irish Flamingo

Little Grebe, Tachybaptus ruficollis

Of the four species of grebe regularly found in Ireland, the Little Grebe (Tachybaptus ruficollis) is the smallest. Little Grebes are found throughout the world, with the European population numbering > 99,000 breeding pairs, of which 1,000-2,500 are found in Ireland (1). A brownish bird, with chestnut cheeks and a lime green spot at the base of the bill in the breeding season (2), they nest in shallow waters of ponds, canals and slow moving rivers. This propensity for shallow waters is due to their feeding habits. As divers, the longer they spend under water, the longer their recovery time (3). This makes smaller water columns more attractive to them as they feed on a variety of arthropods, molluscs and even small fish and tadpoles. Study of the Little Grebe is often problematic due to its secretive nature (4), however it is known that harsh winters affect populations due to reduced feeding oppertunitites when open water sources freeze.

Little Grebe, Tachybaptus ruficollis

The grebes as a family (Podicipedidae) are the only members of the order Podicipediformes, and at first glance these small, diving birds bare little resemblance to the tall, filter feeding flamingo family, Phoenicopteridae. Yet recent analysis of mitochondrial and nuclear DNA from both families (5), as well as cladistic analysis of morphological characteristics (6) showed that the two are sister clades. This points to flamingos evolving, not from a shore like ancestor, but from a highly aquatic one. It also interestingly shows the evolution of two very different feeding strategies (foot propelled diving versus filter feeding) in birds.

References:

1. BirdLife International, 2011. Species factsheet: Tachybaptus ruficollis
2. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 32
3. Fox, 1994. Bird Study 41 pp. 15-24
4. Moss and Moss, 1993. Bird Study 40 pp. 107-114
5. van Tuinen et al., 2001. Proceedings of the Royal Society of London B 268 pp.1345–1350
6. Mayr, 2004. Zoological Journal of the Linnean Society 140 pp. 157–169

First Record of the Linden Bark Borer Moth in the Republic of Ireland

Linden Bark Borer, Chrysoclista linneella

I tend to accumulate pictures of plants and animals unfamiliar to me for identification at a later stage. Some are easy, some hard and some are downright impossible to pin down. Take the little guy above. I knew it was a moth, just about, and a bit of research gave me an idea it was a member of the Cosmopterigidae. Further mining of databases reveled this Cosmet moth to be Chrysoclista linneella (1), The Linden Bark Borer (or, more appealing still, Linaeus' Spangle Wing). A great thank you is due to Angus Tyner of the MothsIreland Project for confirmation of this identity.

Linden Bark Borer, Chrysoclista linneella

However, once had found an identity, the reason it had been so hard to figure out became apparent: C. linneella has never been recorded in the Republic of Ireland (2). It may be even unrecorded in the whole island of Ireland as only one record exists, from Hollwood in Co. Down from 1855 and this is considered doubtful (3).

Linden Bark Borer, Chrysoclista linneella

C. linneella has a holarctic distribution, being found in most of Europe, Scandinavia, Russia and Britain, as well as North America where it was first reported as an introduction in 1928 (4). The c. 11 mm adults have metallic blotches against a vibrant orange wing and are visible from May to September (1). The larvae feed under the back of linden trees (Tilia spp.) and can cause considerable damage to plantations (4).

The specimen pictured was spotted on the bark of a linden tree in July 2010 in an area close to a large container port. This may have been a point of access for the moth.

References:

1. Koster, 2002. Tijdschrift voor Entomologie 145 pp. 103-114
2. Bond et al., 2006. An Annotated Checklist of the Irish Butterflies and Moths (Lepidoptera)
3. Bond, K.G.M, (2009). Microlepidoptera of Northern Ireland Check-list. Northern Ireland Environment Agency Research and Development Series No. 09/02 p. 200
4. Majka, 2005. Canadian Entomologist 137 pp. 620–621

Yellow Bellied Fly

Sciara hemerobioides

The dark winged fungus gnats (Sciaridae) are a large family of flies (c. 1,700 species worldwide (1)), with 104 species alone described in Ireland (2). They are commonly found in moist environments, and some the larvae of some species are pests of commercial mushroom farms, specifically Lycoriella mali (3).

Sciara hemerobioides

Normally these 1 – 11 mm long flies are quite drab in appearance, with black bodies and appendages and dark wings (as the common name suggests). However one species that bucks the trend is Sciara hemerobioides. While its head, thorax, legs and wings are dark like other Sciaridae, it has a bright yellow abdomen with bold black strips across it. The adults can be seen in a variety of damp habitats, such as heathlands and wetlands, where the adults feed on nectar from umbelliferous flowers (4). The larvae feed on fungi and rotting vegetation.

References:

1. Surhone et al., 2010. Sciaridae p. 7
2. Ferriss et al. 2009, Irish Biodiversity: A Taxonomic Inventory of Fauna p. 100
3. Mullen et al., . Medical and Veterinary Entomology pp. 137-138
4. Menzel et al., 2006. Zoological Journal of the Linnean Society 146 pp. 1-147

Common Kidney Vetch and Fragmentation

 

Common Kidney Vetch, Anthyllis vulneraria

Known to many as a coastal plant in Ireland, Common Kidney Vetch (or Lady's Fingers, Anthyllis vulneraria) is also an important constituent of calcareous grasslands, and it is in this guise that is most common throughout Europe (1). This perennial grows to 40 cm high but tens to a prostrate habit. The pinnate leaves are covered in small hairs, as is the stem and it has densely arranged, yellow to orange flowers (2). The flowers bloom for about 8 days (3), during which time some of the main pollinators are the Long Tongued Bee (Anthophora acervorum) and the bumble bees Bombus terrestris and B. jonellus. Both B. terrestris and B. jonellus are primary nectar robbers, in that they bypass restrictions imposed by flower structures to “rob” nectar (3). This often has deliterious effects on plants, but in the case of A. vulneraria such activity actually results in an increase in fruit production. The structure and arrangements of its flowers means that the bodies of the robbers brushes off the flowers, effecting pollination. Flowers open from the bottom to the top, and interestingly the resultant fruit and seeds are significantly heavier on the bottom compared to those further up (4). A. vulneraria is also the only larval food plant of the butterfly Cupido minimus, and unfortunatley both plant and butterfly are considered endangered in Lower Saxony, Germany (5).

Common Kidney Vetch, Anthyllis vulneraria

A. vulneraria has been recently used to show the effects of fragmentation on populations (1). Fragmentation is the overall reduction and breaking up of an organisms habitat, which itself results in population fragmentation for that organism. While fragmentation is thought to be a cause of speciation (6), populations exposed to it then become vulnerable to extinction (7). A study of populations of A. vulneraria in calcareous grassland exposed to significant fragmentation however, revealed little genetic differentiation between fragment populations. This was due to the nature of the use of the grassland as pasture for sheep. As the sheep move from fragment to fragment, they bring with them on their coats, on their feet and in their dung seeds of A. vulneraria from other locations. These new arrivals help keep a diversity of genetic stock in A. vulneraria populations, reducing any inbreeding depression. This indicates that sustainable management of grazing will help to maintain species diversity in grassland pasture.

References:

1. Honnay et al., 2006. Biological Conservation 127 pp. 411-419
2. Krautzer et al., 2004. Site Specific Grasses and Herbs pp. 13-16
3. Navarro, 2000. American Journal of Botany 87 pp. 980-985
4. Navarro, 1996. Plant Systematics and Evolution 201 pp. 139-148
5. Krauss et al., 2004. Biological Conservation 120 pp. 355-361
6. Sahney et al., 2010. Geoligical Society of America 38 pp. 1079-1082
7. Lande, 1988. Science 241 pp. 1455-1460

When is a Wasp a Fly?

Conops quadrifasciatus

With its narrow waist and yellow and black striped colouration, one would be forgiven for assuming Conops quadrifasciatus was a solitary wasp. Closer inspection however reveals one set of wings, as opposed to hymnopterans' two sets, which places it firmly with the dipterans. C. quadrifasciatus is one of a number of similar conopid flies that are present in Europe (1), with 11 species of the family present in Ireland (2). Adults feed on a variety of flowers, including ragwort (Senicio jacobaea) as seen in the pictures.

Conops quadrifasciatus

However, any affinity conopid flies have with hymnopterans is entirely superficial as they are major parasites of bumblebees. The adult female fly attacks foraging worker, male and queen bumblebees outside the nest, placing eggs onto or in the abdomen of the host. The larva hatches and resides in the abdomen of the bee, feeding off haemolymph and the bee's internal organs (3). The bee dies during the last larval stage and pupation takes place inside the body of the bee.

References:

1. Chinery, 1997. Collins Gem Insects p. 202
2. Ferriss et al. 2009, Irish Biodiversity: A Taxonomic Inventory of Fauna p.101
3. Schmid-Hempel et al., 1990. Insectes Sociaux 37 pp. 14-30