Q.My new osteospermum plants have been eaten right through the stems. What would be the cause I had protected with slug pellets
A tray of cosmos have also been dessimated. I wonder if it is a mouse It all happened on the same day overnight.
Certified GKH Gardening Expert
You may want to check for earwigs or caterpillars. Spraying your plants with neem oil could be helpful. If it's caterpillars, spray with Bt.
https://www.gardeningknowhow.com/plant-problems/pests/insects/holes-in-plant-leaves.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/using-bacillus-thuringiensis.htm
Here's an article about African Daisies:
https://www.gardeningknowhow.com/ornamental/flowers/african-daisy/african-daisies-osteospermum.htm