Here is a photo. This type of bug is eating all cabbages that I have planted some weeks ago. Apart from killing one by one, there is any solution? Probably they are living in the organic substrate.
More information please - what, and where are, these seedlings? Where are the cabbages growing, and what in (outdoors, in ordinary soil in the ground, or in pots?) Are these seedlings not planted in sterile seed and cutting or starter soil? Are they in a greenhouse, outdoors, cold frame or indoors? Did you take this photo at night or during the day? Please add photo of damage to cabbages...– BambooApr 1, 2017 at 10:33
@Bamboo they are pak-choi and kale seeds. Planted in outdoor in float beds and the soil is completely wild and organic. The photo was taken at night and the damage is always at night. More photos here imgur.com/a/YXPWs– anvdApr 1, 2017 at 12:51
Earwigs do most of their damage at night. What's at question is whether the soil you've used contained earwig eggs which have now hatched, since you didn't use sterilized potting medium, so you may find more arriving.
Earwigs eat mostly insects, though they do also like to nibble on flower petals quite frequently, and occasionally on plants, and I'm not seeing damage from earwigs on your seedlings, or any other damage actually, so I'm not sure why you think they are eating your seedlings.
If you have cabbages that have been outdoors for some months, I can't comment on what's damaged them because there are no images of the damage, and there are many insects which attack cabbages.
More extensive information on earwigs here http://entnemdept.ufl.edu/creatures/veg/european_earwig.htm, scroll down for its eating habits.
There aren't any insecticides that deal with earwigs, so the usual course of action is to use short, hollow canes laid in between plants, or flowerpots upside down on sticks filled with paper or straw - the earwigs will hide in those for shelter, so every morning, empty them out into a bucket of water and dispose of them.