regnum-plantae:

Raising Pieris brassicae

When I sat one of the RHS horticulture exams last February I had to describe and illustrate the life cycle of the large white, a common pest of vegetables in the Brassicaceae family. Although I had to learn it from books, I had never had a chance to observe all its stages in person so, when I spotted one of these common butterflies taking shelter and depositing her eggs under the leaves of the nasturtium (Tropaleum majus) in my window boxes, I took it upon myself to try and raise them to adulthood. I had never raised butterflies before, so I was particularly excited. 

The tiny yellow eggs hatched in four days and the caterpillars started feeding voraciously on the fresh nasturtium leaves I was providing daily. They grew rapidly and soon started showing their typical mottled yellow/black/green colouration, which is supposed to discourage predators and warn them of their foul taste, acquired due to the mustard oil present in their preferred plants. After two weeks they started pupating: watching the pupae emerge from the skin of the last instar was incredible and something I had never seen before. The soft pupae, already showing the future wing structure, began hardening up and the first butterflies emerged after ten days. They seemed to wait until I wasn’t looking to pop out, so I only caught one halfway through the process and it happened so quickly I couldn’t take a photo. Last night, not long before sunset, I finally released all those that were ready to fly, exactly a month after the eggs were laid. Some immediately flew away, others seemed a bit torpid, probably due to the temperature excursion, so I left them in the shelter of some tall Himalayan balsam (Impatiens glandulifera), hoping for the best. 

I said this before when I raised common frogs (Rana temporaria) last year: animal metamorphosis is an unbelievable natural process which is absolutely worth seeing with your own eyes, I have learnt so much and I can’t wait to raise butterflies again!