12+ Brimstone ova in Garden = 1 male Butterfly.

[Cotswold Cockney]

I have two potted plants of Alder Buckthorn in my garden. Two months ago, I counted at least a dozen freshly laid ova on the plants.

Meantime, strong winds and heavy rain several days, bit like today locally, blew both potted plants over. A check of what remained on the plants showed losses of ova and larvae due to Harlequin Ladybird larvae, Spider, Snail and insectivorous bird predation. We have had broods of Great Tits, Blackbirds and Robins in the garden this and most most seasons. Plus since 1972 when we moved into our newly built house, at least one pair of House Martins nesting under the apex of the Roofing Weather boards although those fine little birds feed almost exclusively on the wing.

So about a month ago I was able to count five larvae only despite a very careful search of the plants. One by one four of these larvae disappeared. Mostly fully or nearly fully grown. I hope they left the potted plants and pupated elsewhere in the garden.

The last larva successfully pupated fully exposed to the elements and any would be predators. Yesterday, very strong winds again blew one of the plants over. Fortunately not the one with the pupa on it. So, not wanting to risk this sole survivor fail to reach maturity and emerge, I carefully cut the small twig it was on and brought it indoors, using a large glass Jar as a safe emergence cage. It emerged soon after bringing it indoors. A perfect male.

This morning, I carefully removed the twig from the Jar with the freshly emerged Brimstone still holding on to its empty pupa case. I carefully placed it under a garden plant with both yellow and green leaves for camouflage. That appeared to work well and it remained there for a while flying off unseen later during the day. I took some images of it indoors last night and in this morning's sunlight. First two outside shots and last two inside house.

So, based simply on my garden experience data, that's about an 8% ova to imago survival rate. I should imagine the rate is far less in the wild. That male will need to survive for at least ten months to find a mate and keep the local population going next year. Good luck to it.

[David M]

Great observations, CC. Well done for planting Buckthorn in your garden. I've wanted to do likewise in the grounds of the private estate where I live but haven't ever been able to find any young shrubs for sale.

[Cotswold Cockney]

Five years ago, I searched/googled :~

"Alder buckthorn rooted saplings"

Have just searched again and that produced a nice selection of options. I bought mine and they arrived in winter when the plants are dormant. First search result showed 10-49 plants @ £1.38p.

I paid about £25 for twenty ~ maybe two dozen ~ bare rooted saplings which were about 30 CM long. Potted up two and planted the rest in my own little nature reserve in a remote part of Gloucestershire. The potted plants grew much quicker than those planted outside. I suspect the type of soil plays a big part here. Those planted out only about half survived beyond two years. The leaf colouring not the same as my potted plants. I also have one Purging Buckthorn in my "reserve" which I planted out five years ago. Got that as a metre high sapling from the AES exhibition. Slow growing, it is now around three metres tall with many branches and lots of healthy leaves Not as shiny green leaves as the wild plants I have seen up on the nearby Cotswold Hills. . I have only ever found one fully grown larva on it. That produced a male Brimstone. Soil again shows these differences.

Some plants thrive and grow vigorously in my "reserve" .. For example Oaks, Willows ( Salix caprea especially ) and even Elms. Others do not thrive such as Celtis, Arbutus ( useful foodplants ) and several others.

[David M]

Thanks for the advice, CC. I've taken note.