Buckthorn or Alder Buckthorn

[selbypaul]

Hi folks
I'm just about to replace a privet hedge in my garden with a Buckthorn hedge, with the intention of attracting Brimstone butterflies. Does anyone know whether Buckthorn or Alder Buckthorn is more preferred by the Brimstone?
Thanks in advance
Paul

[Vince Massimo]

Hi Paul,

I don't think the butterfly has a preference for either species of larval host plant, so your decision should be based upon the type of soil you have. Common Buckthorn (Rhamnus cathartica) is found on calcareous soils while Alder Buckthorn (Frangula alnus) prefers acid soils. I imagine that you would want to keep the spread and height of the hedge under control, but you will not be able to cut it between April and August. I also suspect that the butterfly would prefer an open bush rather a line of cropped plants.

Hope this helps.

Vince

[selbypaul]

Great, thanks Vince

[essexbuzzard]

Plant in a sunny,sheltered position,as brimstones tend to avoid shady,windy plants. Good luck.

[selbypaul]

Also good advice. Thanks

[Cotswold Cockney]

Over the years in Gloucestershire, based on my own observations, the Brimstone prefers Alder Buckthorn locally despite both plants not difficult to find in the Vale of Gloucester or up on the Limestone Hills. Maybe they are easier to find on those "Alder" plants.

Today I counted five very young Brimstone Larvae on my two Potted Alder Buckthorn Plants in my garden... with a bonus on one of them too. A 2/3rds grown Holly Blue Larva feeding on the flower buds and fruits.

Two images of Brimstone larvae and one of Holy Blue :~

[JohnR]

I planted a single Alder Buckthorn and grow it as a tree adjacent to my field hedge which has purging buckthorn in it. I have only seen Brimstone larvae, and only in small numbers, on the Alder Buckthorn.

[Vince Massimo]

On 22nd May I found 21 freshly laid Brimstone eggs on my potted Alder Buckthorn plant. Twelve larvae survived to fifth instar and I collected a few as they started to disperse and pupate. The first adults started emerging this morning.

Brimstone pupa (male) - 10 minutes before emergence 27-June-2017

Releases will have to be delayed until the weather improves.............

Vince

[Cotswold Cockney]

A month ago I counted at least a dozen Brimstone Ova on my two potted Alder Buckthorns in my garden.

Following some heavy rain and strong winds shortly after that count, both my potted plants were blown over. The winds were that strong. Whilst laying on their sides, the plants were open to all manner of creatures to gain access. I removed several near fully grown Harlequin Lady bird larvae ~ carnivorous creatures and ova and small larvae will not last long with those around ~ some small snails and spiders too.

Despite that mishap, I counted five larvae. They are very hard to spot but there may have been more easily missed as so small.

Today, I could only find two Larvae, one fully grown and the other close to fully grown. The larger larva spending time under the leaves now. Maybe preparing for pupation. Although much larger now, still very difficult to spot because of the close match of colour to the surrounding leaves.

By the way, they spend time when not feeding with the raised half of their bodies in a similar way to Apaturinae larvae when they are resting and not feeding.

[Pete Eeles]

Alder Buckthorn would get my vote too, although that's all I've ever had in my garden, and for the last 2 years the single plant has been used profusely by Brimstone. Unfortunately, the local tit population seem to know this too, so I have to sleeve the main branches.

In terms of hedging, I should should also say that Buckthorn is nowhere near as dense as Privet ... thought I'd better mention that!

Cheers,

- Pete

[PhilBJohnson]

I was shown some Brimstone Caterpillars on "Alder Buckthorn" by a Butterfly Conservationist with some expertise this year, just behind a bench where we sat. I guessed the Brimstones hibernated in Ivy or Brambles.
"Blue Tits loved caterpillars and somewhere to hide like Buckthorn bushes, protected by spikes. In another garden, Sparrows hiding from a birdwatchers prize SparrowHawk, headed for the densest part or the middle of the spiked pyracantha, that fed the wood pigeons berries in the autumn."

[KeithS]

I keep both Alder and Purging buckthorns in pots and have found that both are equally and eagerly used by the local brimstones for egg-laying. What I would say though is that the larvae always seem to do better on the Alder Buckthorn: every year for the past five years or so, I've found that maybe 10-20 % of larvae on purging buckthorn suffer from a condition that causes them to dissolve in a pool of black slime as they try to pupate. I have never seen this with larvae on Alder buckthorn. I have noticed that the purging buckthorn leaves often acquire a coating of white mildew on their undersides and I wonder if that has anything to do with it.

[Vince Massimo]

Thanks Keith, that's really interesting..............and welcome to UK Butterflies

Vince

[Cotswold Cockney]

A month ago, I counted at least a dozen Brimstone ova on my two potted Alder Buckthorn plants. Two weeks ago five half grown larvae one, blackened no doubt a spider bite. I think some of the ova were consumed by Harlequin LadyBird Larvae I removed from the plants.

A week ago, three larvae located only all near fully grown. More recently, could only find one of the original five and that fully fed and laid up as a pre-pupa. Probably those are what happens in nature. Many insectivorous garden birds visit and look for food for their youngsters. Have Great Tits [ four youngsters successfully fledged~ one crashed into my wife on its maiden flight .. ] , Blackbirds, Ring and Collared Doves nesting too some years.

Attached pre-pupa images :~

[PhilBJohnson]

An Alder Buckthorn was coined as a "Brimstone Bush", having a potential not to grow as tall as a Buckthorn. As an individual specimen, it might have been more of an attraction to a gardener, being more compact in growth.
Planting schemes of Alder Buckthorn on alkaline, chalk or limestone, might have been considered a mistake. One might have tried ericaceous compost (acidic) mixed with planting topsoil, similar to that used for ones garden Camellia.
Chalk and Limestone geology was permeable (water drained). Alder buckthorn liked damp, water retentive soils.
Consider our native Buckthorn to possibly be a haven for our native birds, being protectively spiked. One recommendation was to plant it sporadically in a hedge (not all together), so that larval predation routines, needed a "habitat hunt". A female Brimstone might travel quite a long distance looking for a suitable place to lay an egg. Farmers interested in native conservation and wildlife, might have considered Buckthorn less common than some of our other, more frequently used (not by a Brimstone) in a hedge, native species, like for example, Hawthorn).
Both Buckthorn and Alder Buckthorn could be purchased during the winter dormant period, bare root, for less weight transportation expense.
This link had some relevance. These Alder Buckthorns were first Spring, after bare root winter purchase:
https://youtu.be/CrmmmgK0lN8