The little black bug in the photo below is a vine weevil and they are particularly active at this time of year. You are unlikely to actually spot the insect in action, partly because it's been too wet to venture out into our gardens this summer, but mostly because vine weevils are nocturnal. The evidence is there if you look for it though -they leave a calling card of notch-like bite marks around the margins of the leaf, where they have been munching.
Where the adult vine weevil inflicts mostly ornamental damage to plants, it's the offspring that are the true shockers.
The larval stage of the vine weevil feeds on roots, and a bad infestation can destroy a small plant. Plants in pots are particularly vulnerable as the pot environment provides a nice nursery ground for the emerging vine weevil larvae.
If there is evidence of the adult beetle being around (notches in leaves), then it's definitely worth treating the ground to get rid of any potential larvae that might be nibbling away on your plant roots.
The best way to do this is by drenching the pot, or the ground with a solution containing a parasitic nematode. The nematodes feed on the larvae, ultimately destroying them. Not what you want to think about over breakfast, but at least no chemicals are involved.
For the nematodes to be successful, the soil must be warm and the vine weevil larvae need to be at a certain developmental stage. Both of these reasons make the end of summer and early autumn perfect times to apply treatments.
For more information on biological controls and suppliers, click on the link below.