Caterpillar nursery on shrub

Caterpillar nursery on shrub

Observation - Caterpillar nursery on shrub - UK and Ireland. Description: Caterpillars making mincemeat of one of my garden shrub's leaves. Gets attacked every year, often to the point of there being no leaves left. Two generations of caterpillars shown in photographs, plus one image of eggs pre-hatching. The caterpillars

Caterpillars making mincemeat of one of my garden shrub's leaves. Gets attacked every year, often to the point of there being no leaves left. Two generations of caterpillars shown in photographs, plus one image of eggs pre-hatching.
The caterpillars often have a stance with their rear ends held aloft. What are these hungry critters, which look to be on the third or fourth batch already this year?