They are http://en.wikipedia.org/wiki/Mealybug  Mealybugs

Seem to have gone mad this year on a spiky yellow daisy's stem. Horticultural Soap is better than Fairy [washing up liquid] and Neem Oil puts off most things and is totally natural.

BT, aka Bacillus Thungurensis is a natural bacteria that kills most things, including Processional Caterpillars, is probably worth a try too.