That's the Andromeda lacebug, Stephanitis takeyai. It's another recent colonist (we seem to get a lot of those here!) and came from Japan. Read more about it here:
Thanks very much for the identification.Have since read much info. on world-wide infestations but have not yet found info. on best way to deal with pest.Both of my pieris bushes are badly affected, one bush is now all most leafless. Are there now any permitted treatments to deal with the insect;or,do I have to destroy my plants. Incidently my plants are more than 20 years old so it seems unlikely that the insect was imported on these plants.ANY advice welcomed
There are some guidelines here:
Unfortunately it's now becoming difficult to buy any insecticides that do a good job, as regulation has banned all the really effective products! I would advise cutting the plants back as far as possible, burning the cuttings, and keeping the area generally tidy. Also check your other plants, and those of your neighbours (if you get on with them!), to see if they have infestations that may be acting as a source. As the bugs have several generations a year, you may need to spray several times a year.