Help! what is eating everything and how do I stop it?

[eastwest]

Novice gardener. Just got first garden (attached to a house). Something in the back garden is eating everything. Plants look like this (photos attached) - leaves stripped off,completely bare. Appears to be the fault of small, grey-white caterpillars with small black and yellow spots. There are also lots of little black grains all over the plants that could possibly be eggs, or insect poo.
What is doing this (are the caterpillars guilty, or are they just in the wrong place at the wrong time) and how do I stop it? It's developed really fast- the plant on the right has been eaten in what seems like a matter of a couple of days. Worried about them moving onto the res t of the garden next!

thanks in advance for any advice :)

From your description, it sounds like sawfly larvae (there are many different species of sawfly which live on different host plants, I get them on Berberis). Probably a bit late now, but you could either spray with dilute washing up liquid (the green method), or blast them with a chemical bug spray. In any case, it is best to eradicate them, as they usually turn up annually.

You can also buy sawfly nematodes to water in the ground that gobble up the larvae (maybe wrong word). They have to be applied at certain times of the year so check the instructions before buying.

.... or possibly mullein moth caterpillars, which don't exclusively eat mullein (verbascum)

Thanks everyone.