Woodlands.co.uk - Pests & Diseases
The holly leaf miner : Phytomyza ilicis
Phytomyza ilicis is a dipteran fly that lays its eggs in holly leaves. It is one of the few insects that is able to make use of holly leaves as a food source / habitat. The female fly lays eggs in the holly leaf (near the main veins or midrib – on the underside) using a thin tube or ovipositor.
The eggs are usually laid in early Spring when there are young and ‘soft’ leaves. Older leaves have a thick and tough cuticle that is far more difficult to penetrate. The larvae or maggots emerge from the eggs and tunnel their way along the midrib / veins emerging some time later into the lamina or blade of the leaf. Here they feed on the photosynthetic tissues of the leaf – the palisade and mesophyll layers, creating a leaf mine (see featured image). The number of leaf mines per leaf is a maximum of three and often just 1 or two. Read more…
Phytoliths, metals and phytoremediation.
Plants take up essential nutrients (nitrates, phosphates, potassium, magnesium etc) through their roots, but some also take up other, more unusual substances – such as silicon, nickel, cadmium, copper, cobalt.
Grasses, in particular, are known to take up silicon and then deposit it in their leaves. The silicon that they absorb is converted into tiny granules called phytoliths, which are often located under the waxy cuticle. Read more…
Horse Chestnut leaf miner moth – an App
Many people have been following the various blogs (and contributing comments) on the problems that Horse Chestnut trees have faced over these last few years. These problems include :-
- bleeding canker
- leaf blotch fungus
- leaf miner moth
The horse chestnut leaf miner moth, which originated in the Balkans, first appeared here in 2002/3 in the South East, but it has since rapidly spread to many areas of the U.K. Read more…
Invasive species – Rats.
Rats (brown and black) have been ‘camp followers’ of humans ever since we adopted a ‘settled’ existence. In modern cities, it is often said that one is never more than 20 yards from a rat. Whether this is true or not, rats have been a pest throughout the millennia, most notably associated with the spread of disease such a bubonic plague but also Weils Disease (Leptospirosis). Read more…
Red squirrels in Scotland.
Threats to red squirrels.
The red squirrel is a delightfully charismatic species, which was once a common native over the whole of the UK, but in England is now restricted to a few small areas. In Scotland, the situation is better, but even here there are only about 120 000 individuals. They represent 75% of the total UK population and are under serious threat, so any actions to protect them are to be welcomed. There are two key threats,
- changes to the woodlands in which they live, and
- the so far relentless spread of the similar, but larger American grey squirrel. Read more…
Horse chestnut leaf miner moth
The ‘progress’ of the horse chestnut leaf miner (Cameraria ohridella) has been reported in the blog from summer 2006 to more recently, when a national survey was under way. This small, but highly efficient parasitic moth was first ‘discovered’ in trees bordering Lake Ohrid in Macedonia in the mid-Eighties. It was later described as species new to Europe, and since that time has managed to spread through almost all of Europe.
Invasion of the killer shrimps
No, it is not the title of a new Stephen King novel but the arrival in the UK of Dikerogammarus villosus. This large freshwater shrimp has its home waters in the region of the Caspian and Black Sea. However, the opening of the Rhone-Main-Danube canal has allowed it to progress through the Netherlands, Belgium, Germany and France. Read more…
‘Toxic caterpillars’ – the oak processionary moth and brown tail moth
Last year, Angus wrote about the oak processionary moth (OPM), which has arrived in this country from Southern Europe. Despite some extreme temperatures over the winter months, the moth has survived and is causing problems again. The featured image (opposite) is from http://www.forestry.gov.uk/fr/INFD-6URJCF.
The moth is a concern and worry on two levels: Read more…