It is not only the Oaks you now need to watch over closely but also your pines too. A new threat to pines is present in the form of Pine Processionary moth (PPM) (Thaumetopoea pityocampa).
It comes from pine woods in central and southern Europe and has been recently found in a container of Pines that were in transit in Strasbourg, France. It is related to the Oak Processionary Moth (OPM) and causes similar damage to pines and weakens the pine trees by feeding on the needles but can also cause death too.
The lifecycle is:
- Egg sacs produced by adult months in August
- Larvae emerge and feed in September
- Caterpillars over winter in nests of silk from October to mid February
- Fully formed caterpillars start processions in spring in around mid February to mid April
- Caterpillars pupate from mid April through to June
- Adult moths emerge from pupae in July and August and lay eggs to start lifecycle off again
The main pine hosts are Stone Pine (Pinus pinea) and Aleppo Pine (Pinus halapensis) and nursery stock in Italy appears to be the worst affected due to defoliation caused by the caterpillars currently but it may only be a matter of time before it reaches the UK.
For more details see the recent article in Horticultural week which was where I originally saw the article: http://www.hortweek.com/Landscape/article/1102985/pine-processionary-moth-its-progress-threat/
So keep a watchful eye on any new trees you buy from any source whether bonsai or nursery stock for any pests that shouldn’t be there.