Strange creatures
 

Helping a friend today with some gardening and we dug up several clumps of
cornflowers - which were close to taking over the bed. One one clump there
were several small white, round, flat bodied insects round the roots and in
the soil under all the clumps were lots of caterpillars - about inch and a
half long, white with black stripes. Never seen caterpillars like this
before - anybody any idea what they are and are they likely to cause damage
to anything else we planted

Jeanne