Background History
Melissa and I were lucky enough to purchase two Thorny Buckthorn plants, at a Butterfly Conservation members day (pre-pandemic).
Considered Planting Schematic
The plants were assumed to be male, as they had not yet fruited. This was convenient for us, because of a possible tummy upset, associated with children eating berries by mistake. Saplings might grow to 6 metres or more, but not that fast, if pruned into a bushy shape. Caterpillars and pupae might hide more in a "interwoven hedgerow" in an over-growing month of June, after sapling leaves had been eaten.
Protected young Brimstone Larvae & Pupae from Predation & Net Covering Timings.
After witnessing a female Brimstone butterfly egg laying (Was from about mid April-mid May, (2022 in Lincolnshire) depending on sunny flight temperatures, above 16ºC. About 2-3 weeks after, young larvae could be protected from predation with a large micro mesh net, covering a bush (a bit like one might protect red currents from wood pigeons) but the smaller netting mesh holes, might also have stopped other insects from entering, for example, wasps. The immature stages of the Brimstone, relied on camouflage, as a form of defence, but where many eggs were deposited on a single Buckthorn, many or all larvae were likely to be eaten in final instar, predated by hungry birds, instinctively coming back for another meal, once one was found. Where a micro mesh net was used to protect small larvae (insignificant meals for birds), it was thought that 90-100% of Brimstone larvae might be reared to pupation. At this point, I want to stress that I do not believe in catching a mated female Spring Brimstone butterfly and put under a netted Buckthorn. I do not believe in that principle and have never, to my knowledge done it and don't know what that outcome might be. I believe in the freedom of the sexually mature Brimstone butterfly flight, for the enjoyment of the majority.
Pupation & Emergence from pupae Timings
Although a Brimstone butterfly might live for 10 months, and be single annually brooded, breeding in the Spring, brood, to build a big enough larval body, in time with deciduous Buckthorn, one was only a pupa, for about 16 days, during high summer, when outside temperatures were at their hottest. Although eggs might have been laid 1 month apart, daylight length above 16ºC, with fast larval and pupal development, meant that many butterflies emerged from pupae, at about the same time. There might have been about, a 10-15 day period, from first butterfly emerging, that it was essential to check nets and release butterflies, that had taken two hours & dried their vulnerable wings, at that stage. It was recommended, when temperatures were above 16ºC, to check nets, 3 times a day, let a butterfly find it’s feet first, on a wild flower, before fully discovering it’s own distance flight, in sunny temperatures above 16ºC.
This process was important to someone, so that “friends of the planet” did not turn up uninvited in someone’s garden at first butterfly flight time and in naivety, decide to take releasing butterflies, into their own perfectly timed hands.
Climate Changing
We know that many species can be lost very quickly, when “tables are tipped” when global heating, reached a tipping point, but by studying this science, something can be monitored from year to year. It was thought that in 2022 in Lincolnshire Brimstone butterflies emerged from pupae as butterflies, on my local Lincolnshire average, about 0-10 days earlier, than in 2021. Ovipositing flight time, seasonal variations, were thought to be one reason for this.
I wanted it seen that captive rearing outside, to protect from predators, parasites and/or wasps, was distinctly different from captive breeding inside, stageset photography and scientific study, that was plausibly important, at very least, for a child’s interaction & life cycle understanding in scientific learning.
Some Conclusions
These issues became important to me, as the sub species in Northern Ireland was fully protected under Wildlife (Northern Ireland) Order 1985.
The Wildlife and Countryside Act 1981, applied in England, but in England, with increasing urbanisation, with national human population growth and declining butterfly numbers, we thought that gardeners that specialised, should be given a chance, to let others, be excited to see more butterflies & have them complete their life cycles, locally, in gardens, with help.
- July 6th 2022 Freshly emerged, male Brimstone butterfly