NATURE NOTES: Invasion of the Greenfly
I'm not sure if it's just because I've started taking notice of just how many Greenfly are about this year or whether the Greenfly are having a particularly good year!
I'm sure the warm, humid, sometimes sunny weather has something to do with the swarms that are in 'clouds' at the moment.
Greenfly, or more correctly Aphids, are sap-sucking insect pests, ranging in size from 1-7mm (1/16-1/4in) long.
Aphids are also known as greenfly and blackfly, but other types may be yellow, pink, white or mottled.
Some species, like woolly beech aphid and woolly aphid on apple, cover themselves with a fluffy white waxy secretion.
Most aphids feed on foliage, stems and flowers but some suck sap from the roots.
There are more than 500 aphid species in Britain. Most species will only attack one or two plant species, but others will attack a wide range of plant hosts.
Almost all plants are affected, including ornamental plants, vegetables and fruits, greenhouse plants and houseplants.
On the plus side aphids have many natural enemies, including ladybirds, hoverfly larvae, lacewing larvae and several parasitic wasps.
For much of the year, aphid colonies consist of wingless females that give birth to live young.
Winged forms develop when overcrowding or deterioration in the host plant induces a need to move to another plant.
Most aphid species overwinter as eggs but some can remain as active aphids, particularly in mild winters or on indoor plants.
Many aphids, especially those on fruits and vegetables, go through an annual cycle that involves two different host plants. The plant on which overwintering eggs are laid is usually a tree or shrub.
In the spring, the eggs hatch and the aphids feed on the young foliage.
By early summer, the foliage has grown older and tougher, inducing winged forms of the aphid that migrate to the summer host plant. This is usually a non-woody plant with soft, succulent foliage.
Some aphids, however, spend the whole year on one type of plant, although they may be active for only part of the year. Some aphids transmit plant virus diseases when they move from one plant to another.
This is a particular problem on soft fruits, such as strawberry and raspberry, and some vegetables such as tomatoes and plants of the cucumber/marrow family, and on some ornamental plants, such as dahlias, lilies, pelargonium, tulips and sweet peas.
There are more than 500 species of Aphids in the UK.
Greenfly have six legs, two antennae (feelers) and some have wings.
They have mouthparts like a straw to suck sugary sap from plants.
Greenfly produce a sweet liquid called honeydew from pores on their backs because they suck so much sap.
Lots of this liquid can fall from trees causing parked cars to become sticky and dirty in summer!
A greenfly born on a Tuesday can be a grandparent by Friday. Not all Greenfly are green! They all look similar but some are black and some are brown.
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Weather for Wigan
Thursday 09 September 2010
Today
Light rain
Temperature: 11 C to 18 C
Wind Speed: 13 mph
Wind direction: West
Tomorrow
Light rain
Temperature: 15 C to 20 C
Wind Speed: 16 mph
Wind direction: South west
