Maggie took these pictures, fascinated by watching this mother depositing eggs beneath a nasturtium leaf… the first time she had witnessed this. You can just make out the yellow eggs. I don’t know if the aphids will out compete the caterpillars when they hatch?
Large White Butterfly Pieris brassicae with ovipositor in action
Commonly called cabbage white they are well known for their use of brassicas as food plants. I once went on holiday for a week just before my cauliflowers were ready to harvest. I returned to find (and this is no exaggeration) just a row of stalks with a neat heap of caterpillar poo* besides each one!
Here are the eggs she laid.
*Frass is the proper term for insect poo.