green beetles on my cauli

Some of my cauli is coming on great, but some looks like it's been nibbled, perhaps by the infestation of slugs that has decimated nearly everything I've planted this year.  The florets have become separated and some seem to be growing faster than others, and they generally look really poor and discoloured.  While I was examining them for slugs I've discovered a green beetle-like insect that looks like a cross between a beetle and a cricket and is bright sap green.  Is this a pest?  Is it causing the damage?  I can't find it in any of my gardening books.  I'll try and get a photo, but they're very fast & I haven't been able to catch one.

Green shield bug? -like this

 just a thought

Its called a 'Shield' insect and is harmless ... I have loads in my garden !

Chris

Yea, it does look like this, only no brown on it.   And it's really really green.  I also found a couple on by strawbs, but other than slug damage I couldn't see other damage, so I've stopped worrying.  I think my cauli just suffered root rock & was just poor.  It's the first time I grew it, and I'd defo do it again, as the couple of good ones were so delicious.  Thanks a mill for your replies.  I have gained so much from everyone on the forum, I'm sure everyone else has too.  Bless

This year I grew cauli & cabbage in raised bed this year, put compost from bin, compost from bag, and new top soil, trod it down well and covered it with a fine net to deter the cabbage fly and slugs. for my labours i  got purple tinged cauli heads??? still got loads of caterpillars too? Could the eggs have been on the plants when i got them from the nursery, I bought plants as i'd never had much luck with them before so avoided seed this year.  the ones that aren't purple have cream sprouts, suppose there's no chance that they'll merge together to form a nice even head....... anyone else's cauli turned purple in the rain??

Can you remember what variety you grew? I've put in January King, a savoy variety that grows with a blueish purple tinge though mostly green.

http://www.britishbugs.org.uk/gallery/heteroptera/Pentatomoidea/pentatomoidea.htmA                  A gallery of shield bugs - as you can see they come in more than 1 colour.

l