''Euceraphis betulae'', the birch aphid or silver birch aphid, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...

. It is a tiny green insect with a soft body and wings. It is found living on the European silver birch tree (''

Betula pendula ''Betula pendula'', commonly known as silver birch, warty birch, European white birch, or East Asian white birch, is a species of tree in the family (biology), family Betulaceae, native plant, native to Europe and parts of Asia, though in so ...

'') where it feeds and multiplies on the buds and leaves by sucking sap.

Description

The silver birch aphid is a light green colour with a bluish tinge. The blueness is due to the dusting of blue wax particles which are particularly obvious on the antennae and legs. All adults have membranous wings and during the spring and summer, all individuals are female. The mouthparts are specialised to form a slender stylet for piercing and sucking

sap Sap is a fluid transported in the xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a s ...

from their

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

tree.

Biology

Eggs that have overwintered on birch twigs hatch out in the spring. The

nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...

feed on the leaf buds as they burst and on tender young leaves. They grow rapidly into winged females that, as soon as they are adults, start to reproduce by

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

, producing live young. This new generation develops into further winged females and the numbers of aphids soon builds up. They take to the wing rapidly if disturbed. Some fly to nearby silver birches and others to other parts of the same tree but by about July they stop reproducing. In September the birch leaves begin to turn yellow and the aphids resume reproduction and further nymphs are born viviparously. As the days shorten, there is a change in the reproductive pattern. The next generation of adults produced consists of greyish, winged males and brown, winged egg-laying females. After mating, the females lay batches of orange eggs on birch twigs. The adults die off and the eggs soon turn to a glossy black colour. They are able to withstand harsh winter weather and hatch in the spring when the tree is about to resume growth.

Ecology

Like many other species of aphid, ''Euceraphis betulae'' is very specific as to the identity of its host. The silver birch is an ornamental tree native to Europe which has been introduced into North America, Australia, New Zealand and other parts of the world and the aphid has travelled with it. The aphid has not adapted to colonise other species of birch native to these countries. In Europe, the closely related ''

downy birch ''Betula pubescens'' (syn. ''Betula alba''), commonly known as downy birch and also as moor birch, white birch, European white birch or hairy birch, is a species of deciduous tree, native and abundant throughout northern Europe and northern Asia ...

'' (''Betula pubescens'') has its own species of aphid, '' Euceraphis punctipennis''. At one time this was thought to be identical to ''Euceraphis betulae'' but there have been found to be

chromosomal A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most importa ...

differences between the two, and they are now considered to be separate species. Ladybirds and their larvae feed on aphids. In America the eyed ladybird ('' Anatis ocellata'') specialises on the aphids colonising various trees. Their diets include the silver birch aphid and pine aphids. The cream-spot ladybird ('' Calvia quatuordecimguttata'') also feeds on ''Euceraphis betulae''.

References

{{Taxonbar, from=Q5405776 Aphididae Insects described in 1855 Hemiptera of Europe