By Richjones
United Kingdom 
We have a plum tree which last year was attacked by plum sawfly. I have found advice on the web which says dig the soil at the base of the tree to disturb the overwintering pupae and spray the blossom with derris. That however is no longer available. The only product I can find is from HSD ONLINE whose recommended their product-PROTECTOR NATURAL INSECT KILLING PRAY FOR ALL PLANTS but the instructions for use say it should not be sprayed on the blossom but as I understand it the flies lay eggs directly on the blossom from where the maggots then tunnel into the fruit so it would appear that using a product which can be sprayed onto the flowers is essential. What is your advice please?
Thank you. Richard Jones.
8 Mar, 2012
Answers
many thanks for the reply. i look forward to hearing further
11 Mar, 2012
Hello, Richjones ... I have been advised by my local garden centre to apply plum moth traps in May. They are advertised as a 'monitor' because EU laws say they cannot be described as a 'preventer'. However, the males are trapped and cannot propagate!! Anyway, they also recommend we use a bug spray on the buds and leaves, to prevent, repel or kill resident saw fly bugs eggs hatching out that are laid on leaves and in the blossom. Together with the grease trap, for those currently hibernating underground, we are covered!! Hope this helps.
14 Mar, 2012
thanks very much for this. I will try it all. Good luck!
Rich Jones
15 Mar, 2012
Hello Richard! I am currently investigating this for myself. My local Garden Centre has advised they will have specific pest control available in next two weeks. I will let you know the name and type. In the meantime, in case of warm early weather that may hatch the grubs, I have been recommended by them to slap on the main stem about 6-8 inches off the ground as much vaseline as I can get to stick to the stem! Worth a try ... talk to you soon.
10 Mar, 2012