Insects go with gardening, it's what they do
What gardeners try and do is get a balance between devastion and delight

It really comes down to "Know your enemy", some are harmless and some will eat the lot

The one you picture, vine weevil is a slow burn culprit. The adult nibbels leaves but generally behaves, it's the larvae stage [underground grubs] of the weevil that are the problem, they eat the roots

In open gardens this is not a big problem because they are prey to birds, beetles etc. In raiseds beds or even worse in pots thay have no where else to go so will devastate an entire crop

There are pesticides for them, and I think some sort of organic predator, maybe others have experience of that method.

generally in open, raking will bring them to surface and the birds will take care of them

it is perfectly normal to find all sorts of insects and small invertebrates in soil. Usually they indicate a healthy soil.
Has she seen vine weevil adults? If yes then they need picking off and crushing.

Are the plants being damaged? She could put a empty half of an orange [the skin after it has been squeezed] on the beds in the evening to trap any small slugs/snails. Other wise it just needs leaving to settle and adjust to the natural wildlife normally found in soil.

the chicken pellets will attract insects as they break down. All normal.
hope this reassure your daughter in law.

The main trouble with these vine weevils is caused by the grubs which live in the soil. They are little pale c shaped things that eat the roots. Is the picture of one you have seen? Slugs and snails are a nuisance too and love nice tender seedlings. They usually hide during the day and come out at night to chomp away at your tender plants. You can put slug pellets down (just a few not a handful!) but cover them with something so the birds don't eat the dead there will hopefully be! A large stone or flattish piece of wood will do - the slugs will go under it to eat the pellets and die there.(Oops sorry Grandad G - just seen that you described these little pests as well...)