Question Author
To those of you who responded to my query - a belated grateful thank
you.
heathfield, I haven't tried Raid yet as I went to the site recommended by alavahalf and have now placed an order. gingejbee, I don't possess the knowledge to know if pyrethroids are contact rather than systemic.
And finally woofgang - DON'T give up. I bought tubers in 2010 and subsequently forgot them - left in the garage. The following year I planted them despite being shrivelled and seemingly dead and they grew. Unfortunately, both flowers and greenery were completely consumed by the Lilly beetle. Last year (2012), having left them outside for the winter, they came on again. This time I treated them with DOFF SYSTEMIC INSECTICIDE and had a great display with no Lily beetle attack. DON'T give up. Find a systemic insectide. (the one I used is now a banned substance).
Regards Curtis.