additives to larval hostplants for larger growth of lepidoptera

Hi,

I remember reading an article ages back regarding the spraying of nutrient solutions on larval hostplant leaves for increased growth of lepidoptera larvae.

Just curious if anyone has tried this recently and has information on making possible nutrient additives for this.

Overall i am just curious and want to try this on a few extra Sphinx larvae I have on the go.

Cheers,
Steve.