thanks for info waaiting for an answer when ready
thanks once again
chow

Welcome, Mightymo!
The babies are little green caterpillars that chew holes and irregular pieces out of the edges of the leaves of members of the Mustard family--cabbage, broccoli, Brussels sprouts, cauliflower,etc. They work at night, so you hardly ever catch them in the act. Sometimes, it's a good idea to go out after 10 pm with a flashlight to confirm the diagnosis, since snail and slug damage can look much the same. If it is the caterpillars, either pick them off and squash them--rarely completely effective--or spray with spinosad or B. t. Both of those products are considered organic, but spinosad kills bees, so spray it when the bees aren't active (safe when dry); and I understand that B. t. is hard to get in Europe. Good luck!

And as for the butterfly itself, it looks like its name - white winged butterfly.

You can spray to protect using Garlic Barrier which makes the plants smell of garlic so no insect goes near. Doesn't work though if the caterpillars are already there, you can pick off by hand (wear rubber gloves if you are squeamish) or try spraying with a mix of eco friendly washing up liquid (not the normal 'fairy' type stuff) and water.

to Tuqbrethill Bamboo Moon Grower..
am new to this game
but many thanks for your answers and information
cant see any nibbling yet will keep an eye out
swat the cabbage white
and spray with soapy liquid

once again thanks

Just remember that the washing up liquid only works if you spray it on the caterpillar itself--and they're really good at hiding!

Could this explain the mysterios holes in my sunflowers until recently where healthy ,now its too high for slugs and no trail signs,keep checking for catterpillars.and nothing? only top 5ft and growingleaves affected

Tips for finding caterpillars: go out at night with a flashlight; look under nearby un-chewed leaves--they're sneaky that way--or look on the sheltered side of the stem, farther down. Other possible culprits on sunflowers are: grasshoppers and katydids--large, very irregular holes, with the culprit rarely found in the day--or flea beetles--little round holes, like someone has been shooting the leaves with a shotgun, though the little iridescent black or navy beetles are usually pretty obvious. Good luck, Chega!

Thanks,I will do the try the flashlight again on surrounding leaves, and take on what you say about the other culprits.I was sort of eliminating catterpillars thinking it was something of a fast mover like a grasshopper or something

to tugbrethill fm mightymo many thanks for the info ...
unfortuneately i havent found the little devils yet will keep trying tks

Sometimes you don't find grasshoppers 'til they're the size of Havana cigars! The caterpillars are usually nearly the same color as the leaves they feed on, and hide in odd corners, like right next to a big leaf vein, or sit with their back legs on the stem and the rest of their body sticking out at an angle, thinking, "I'm just a broken off leaf, ignore me." Annoying little critters!

lol