The Brimstone Project
@brimstone-project.bsky.social
Understanding the Brimstone butterfly's life cycle and creating conditions for it to thrive.
Clouded Yellow (Colias croceus) apparently feeding on Golden Samphire (Limbarda crithmoides), Dengie peninsula October 12th.
December 30, 2025 at 6:02 PM
Clouded Yellow (Colias croceus) apparently feeding on Golden Samphire (Limbarda crithmoides), Dengie peninsula October 12th.
Lammas Growth 2 - Once the shoot was established, one of the leading branches began to grow and then flower.
August 25, 2025 at 7:00 PM
Lammas Growth 2 - Once the shoot was established, one of the leading branches began to grow and then flower.
Lammas Growth 1 - By mid July this tree had stopped growing. From mid-July a shoot emerged and is documented over the next few weeks.
This potted tree is watered regularly. None of the trees planted out and fending for themselves have experienced Lammas growth.
This potted tree is watered regularly. None of the trees planted out and fending for themselves have experienced Lammas growth.
August 25, 2025 at 4:57 PM
Lammas Growth 1 - By mid July this tree had stopped growing. From mid-July a shoot emerged and is documented over the next few weeks.
This potted tree is watered regularly. None of the trees planted out and fending for themselves have experienced Lammas growth.
This potted tree is watered regularly. None of the trees planted out and fending for themselves have experienced Lammas growth.
Frangula alnus, Alder Buckthorn seeds. One berry contained two seeds.
August 25, 2025 at 3:49 PM
Frangula alnus, Alder Buckthorn seeds. One berry contained two seeds.
Sunday 24th August, sunny, a bright green male Common Brimstone, disturbed, flying near to the young Alder Buckthorn trees.
August 25, 2025 at 2:44 PM
Sunday 24th August, sunny, a bright green male Common Brimstone, disturbed, flying near to the young Alder Buckthorn trees.
Alder Buckthorn (Frangula Alnus) berries forming. These saplings were planted as seedlings in March 2024. In their first year they did not flower. In their second year they successfully flowered and are now forming berries. 22nd June.
June 23, 2025 at 7:37 PM
Alder Buckthorn (Frangula Alnus) berries forming. These saplings were planted as seedlings in March 2024. In their first year they did not flower. In their second year they successfully flowered and are now forming berries. 22nd June.
One of the two last caterpillars observed. This one started feeding again just minutes after being disturbed. This Alder Buckthorn is still flowering. 15th June.
June 23, 2025 at 7:28 PM
One of the two last caterpillars observed. This one started feeding again just minutes after being disturbed. This Alder Buckthorn is still flowering. 15th June.
Spiracles through which the larvae breathes. There are 9 down each side of the body, 1 thoracic and 8 abdominal.
June 21, 2025 at 9:39 AM
Spiracles through which the larvae breathes. There are 9 down each side of the body, 1 thoracic and 8 abdominal.
Midabdominal prolegs in action.
Searching for chrysalises I disturbed the last two visible Brimstone butterfly caterpillars. Both on the same Alder Buckthorn plant and both found in this en garde posture. 15th June.
Searching for chrysalises I disturbed the last two visible Brimstone butterfly caterpillars. Both on the same Alder Buckthorn plant and both found in this en garde posture. 15th June.
June 21, 2025 at 8:54 AM
Midabdominal prolegs in action.
Searching for chrysalises I disturbed the last two visible Brimstone butterfly caterpillars. Both on the same Alder Buckthorn plant and both found in this en garde posture. 15th June.
Searching for chrysalises I disturbed the last two visible Brimstone butterfly caterpillars. Both on the same Alder Buckthorn plant and both found in this en garde posture. 15th June.
A first attempt to show the Brimstone caterpillar feeding on Alder Buckthorn. A Video might be better. Feeding is frenetic, chomp, chomp, chomp, eating the leaf in a curved action. Repeated over and over along the leaf margin.
Then resting along the midrib. Still and safe.
Then resting along the midrib. Still and safe.
June 12, 2025 at 8:16 PM
A first attempt to show the Brimstone caterpillar feeding on Alder Buckthorn. A Video might be better. Feeding is frenetic, chomp, chomp, chomp, eating the leaf in a curved action. Repeated over and over along the leaf margin.
Then resting along the midrib. Still and safe.
Then resting along the midrib. Still and safe.
A grim find. A dead or paralysed Brimstone caterpillar laying on an uneaten leaf. Its not obvious how it met its end. I thought it might have been parasitised but I am sure now that is not the case.
June 11, 2025 at 8:29 PM
A grim find. A dead or paralysed Brimstone caterpillar laying on an uneaten leaf. Its not obvious how it met its end. I thought it might have been parasitised but I am sure now that is not the case.
Evidence of a Brimstone butterfly larvae's final moult (ecdysis) from 4th to 5th instar. Anchored at the leaf base the caterpillar exits the old cuticle in a forward direction. Then off to find a clean new leaf?
Something else happened here. Is that the remains of a Damsel Bug?
Something else happened here. Is that the remains of a Damsel Bug?
June 11, 2025 at 8:07 PM
Evidence of a Brimstone butterfly larvae's final moult (ecdysis) from 4th to 5th instar. Anchored at the leaf base the caterpillar exits the old cuticle in a forward direction. Then off to find a clean new leaf?
Something else happened here. Is that the remains of a Damsel Bug?
Something else happened here. Is that the remains of a Damsel Bug?
This might be one a reason for Brimstone butterflies not to choose larger Buckthorn trees as larval hosts. Warblers such as this Garden Warbler seen singing in Alder Buckthorn (Frangula alnus) are known to eat Brimstone butterfly caterpillars.
June 11, 2025 at 1:33 PM
This might be one a reason for Brimstone butterflies not to choose larger Buckthorn trees as larval hosts. Warblers such as this Garden Warbler seen singing in Alder Buckthorn (Frangula alnus) are known to eat Brimstone butterfly caterpillars.
4th instar common brimstone butterfly larvae. Note the amber fluid exuded from tips of fine hairs along the body. The fluid is thought to be a defense mechanism possibly discouraging predators with a foul taste.
June 3, 2025 at 6:55 PM
4th instar common brimstone butterfly larvae. Note the amber fluid exuded from tips of fine hairs along the body. The fluid is thought to be a defense mechanism possibly discouraging predators with a foul taste.
3rd instar brimstones 31st May 2025
June 3, 2025 at 7:36 AM
3rd instar brimstones 31st May 2025
3rd instar common brimstone. 8 or 9mm long. Resting along midrib of the upperside of the alder buckthorn leaf.
May 31, 2025 at 7:50 AM
3rd instar common brimstone. 8 or 9mm long. Resting along midrib of the upperside of the alder buckthorn leaf.
2nd or 3rd instar common brimstone butterflies resting between meals. About 6mm long suggests 2nd instar. According to Peter Eeles in his book Life Cycles of British & Irish Butterflies 2nd instar catapillars would rest on the underside of the leaf. 3rd instar rest on the upper side of the leaf.
May 31, 2025 at 7:41 AM
2nd or 3rd instar common brimstone butterflies resting between meals. About 6mm long suggests 2nd instar. According to Peter Eeles in his book Life Cycles of British & Irish Butterflies 2nd instar catapillars would rest on the underside of the leaf. 3rd instar rest on the upper side of the leaf.
Two second or third instar common brimstones on Frangela alnus. 25th May 2025.
May 30, 2025 at 8:39 AM
Two second or third instar common brimstones on Frangela alnus. 25th May 2025.
Alder Buckthorn (Frangula alnus) flowers. Each about 3 or 4mm across. Flowers beginning to open in late May.
May 27, 2025 at 5:44 AM
Alder Buckthorn (Frangula alnus) flowers. Each about 3 or 4mm across. Flowers beginning to open in late May.
Brimstone eggs.
May 13, 2025 at 5:33 PM
Brimstone eggs.