Sarah Arnold
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sejarnold.bsky.social
Sarah Arnold
@sejarnold.bsky.social
2.7K followers 4.3K following 260 posts
Entomologist, likes pollination, insect behaviour, IPM, horticulture and agriculture, sustainability, nature and especially wild bees.

Works at Niab (UK). Views my own. she/her

Neurodivergent, quirky, sometimes wrong but usually teachable.
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sejarnold.bsky.social
I checked the common mallow & sure enough, there was a Podagrica sp. In this case, P. fuscicornis, the red-legged one. I need to do a thread about the Podagricas of common mallow in the UK as they're more interesting than you'd expect for tiny flea beetles...

#KentNature #Kentomology #Coleoptera
August 3, 2025 at 9:04 PM
sejarnold.bsky.social
I am not sure if this Misumena thought it was well-camouflaged... [3/]

#KentNature #Kentomology #Spider
A pinkish purple thistle flower with a bright yellow crab spider sitting underneath looking quite obvious and not at all cryptic!
August 3, 2025 at 9:02 PM
sejarnold.bsky.social
A particular feature of the site is that is has a population of Sitaris muralis that was first noted by @baldbirder.bsky.social in 2024 and was back in force this year. The beetles parasitise nests of Anthophora plumipes. [2/]
A black beetle with distinctive orange shoulders, on a brick wall that has holes in the mortar. (Sitaris muralis.) Foreground shows at least 3 black beetles with orange shoulders in a big pile. They all have weird reduced elytra that don't fully cover the wings or abdomen. Background shows another beetle. All are on concrete with sandy surface. A very distended S. muralis in a glass tube. Abdomen is dark brown, rest of beetle is black apart from distinctive yellow-orange shoulders. Beetle is right way up but legs scrunched under it as dead. A hole in brickwork/mortar with spider webbing forming a tunnel, in which a large dark coloured spider sits among at least 2 dead Sitaris muralis beetles.
August 3, 2025 at 7:09 PM
sejarnold.bsky.social
Yesterday's @kentfieldclub.bsky.social meeting was at @niab-uk.bsky.social's East Malling site, which has orchards of various ages and management, and wildflower areas (though the visitor car park was also biodiversity-rich).

The site has a wide diversity of bees! [1/]
#KentNature #bees #entomology
A very cute small bee with big green eyes sitting on the tip of a person's finger (Anthophora quadrimaculata) A large bee on a yellow Asteraceae type flower. She has brown-golden hair on her thorax and her hind legs are covered in spectacular yellow-golden flowing hairs. (Dasypoda hirtipes) A fairly large bee in a petri dish, with a black and fairly unhairy abdomen upper side, but you can just about see the underside has thick, stiff orange hair (black at the tip) for pollen carrying. Her thorax is hairy light brown and has lots of yellow pollen on. (Megachile willughbiella)
August 3, 2025 at 6:34 PM
sejarnold.bsky.social
Very heavily damaged Polistes sp. spotted on the Niab East Malling site on Friday - have to admire how it was still foraging despite the serious damage on the abdomen.
#KentNature #Kentomology #Entomology #KentInsects #PaperWasp #Polistes #Wasp
The white frothy "platform" of flowers from an Apiaceae plant, on which a medium-sized wasp is sitting. The wasp is black and yellow striped, but a bit more gracile and leggy than a "normal" Vespula. This individual has a partly-crushed abdomen, with T1 and T2 both distorted badly. The white frothy "platform" of flowers from an Apiaceae plant, on which a medium-sized wasp is sitting. The wasp is black and yellow striped, but a bit more gracile and leggy than a "normal" Vespula. This individual has a partly-crushed abdomen, with T1 and T2 both distorted badly, and the insides partly visible at the T3 join. The white frothy "platform" of flowers from an Apiaceae plant, on which a medium-sized wasp is sitting. The wasp is black and yellow striped, but a bit more gracile and leggy than a "normal" Vespula. This individual has a partly-crushed abdomen. The white frothy "platform" of flowers from an Apiaceae plant, on which a medium-sized wasp is sitting. The wasp is black and yellow striped, but a bit more gracile and leggy than a "normal" Vespula. This individual has a partly-crushed abdomen, with T1 and T2 both distorted badly.
July 20, 2025 at 2:10 PM
sejarnold.bsky.social
Some photos from today, all at or close to home: Pantaloon bee (Dasypoda hirtipes), Fiery clearwing, Wall brown. #insect #entomology #KentMoths #KentNature @kentfieldclub.bsky.social
A pale purple-pink pompom of a thistle on which a large bee with absolutely splendid fluffy bright orange pantaloons perches. She is otherwise quite chunky, with a black and white striped abdomen and golden hairs on the thorax and she contrasts quite nicely against the flower. A yellow cluster of ragwort flowers, a little bit tatty, on which a skinny, weird-looking moth with orange-scaled almost waspy wings sits. Its body is black with some white markings and its wings are narrow so it looks more like a wasp than a normal moth really. A brown/orange patterned butterfly sitting among dry grass.
July 6, 2025 at 1:37 PM
sejarnold.bsky.social
Hummingbird hawkmoth caterpillar in North Kent, in a wildflower patch allowed to grow tall on a new housing estate! @kentfieldclub.bsky.social #KentMoths #UKMoths
A fairly plump green caterpillar with a white stripe all down its side, and a tail-horn (what is it called?) that is blue with an orangey-yellow tip. Sitting on hedge bedstraw (tiny white flowers).
July 5, 2025 at 8:36 PM
sejarnold.bsky.social
Information about it says it also uses Echium vulgare. I'd not seen it on our Echium, but I had a look today, and there are a small number of individuals on it. They seem to be all/mostly the pale morph (or young individuals?), so that's interesting. [7/7]
A long, dark green and hairy leaf on which a small, slightly shiny, oval-shaped beetle is sitting. The beetle is kind of golden-brown colour and has large black femora (just visible). There is minor feeding damage on the leaf surface.
July 5, 2025 at 8:22 PM
sejarnold.bsky.social
L. quadriguttatus feeds on leaves & roots of houndstongue. In N. America there have been attempts to use L. quadriguttatus as biocontrol, but the feeding makes a mess of the plants without actually killing them or stopping them from reproducing, so probably not a suitable control method. [5/]
A green, hairy and long leaf, pinched between fingers, on which a small 3mm long beetle is perched precariously. The beetle is black and shiny, has large femora for jumping, and four orange splotches on its elytra. The leaf has many brown-edged, irregular holes from herbivore (beetle!) feeding damage.
July 5, 2025 at 8:21 PM
sejarnold.bsky.social
Meet my new friend-species and current favourite flea beetle, the houndstongue flea beetle Longitarsus quadriguttatus. (Is it OK to have a favourite flea beetle?) [1/]
Close up of a tiny beetle (3mm long?) inside a glass tube being held in a human hand. The beetle has large hind femora for jumping, and otherwise is black and shiny, with long antennae, and four orange-red spots on its elytra.
July 5, 2025 at 8:18 PM
sejarnold.bsky.social
Thank you to everyone sending us #AppleBlossomWeevil capped blossom from their UK #orchards and trees. We are spotting some really interesting parasitoids developing - two or maybe three species. This implies we have some natural enemies of this re-emerging pest already present in the UK.
A highly magnified microscope image of a yellow-white pupating wasp. The wasp's body is fairly slender and still pale as it develops. It has long antennae, and its eyes are brown. It is probably 2mm long and lying on tissue paper. A highly magnified microscope view of a yellowish pupating wasp. Its body is fairly slender, its eyes are brown and its legs are long. It lies on tissue paper.
May 9, 2025 at 8:51 AM
sejarnold.bsky.social
If you gently ease those crispy brown petals away, you find a little space in which a C-shaped pale green larva is happily hanging out. [6/]
A "capped blossom" from an apple tree where the brown leaves have been eased back to reveal a pale larva inside the damaged blossom. The blossom has had the anthers, etc. of the developing flower all eaten away.
April 30, 2025 at 10:18 AM
sejarnold.bsky.social
The larva lives inside the blossom, munching away on the developing flower parts. This stops the flower opening or developing normally, so you end up with "capped blossom", buds that are crispy and brown on top and don't open. [5/]
A close-up image of an unopened apple bud that has turned brown and crispy from ABW damage.
April 30, 2025 at 10:16 AM
sejarnold.bsky.social
Apple blossom weevil (Anthonomus pomorum) is one of those pests that was a Big Problem in UK/European apple orchards, then ceased to be a big problem for a few decades, and is recently returning with a vengeance. [1/]
A weevil about 5mm long, with ridged elytra and a paler v-shaped band across the abdomen (otherwise dark grey-brown). It is crawling across an apple blossom cluster on a tabletop, which is green and downy.
April 30, 2025 at 10:11 AM
sejarnold.bsky.social
If you visit an orchard with noticeable capped blossom, we would be delighted if:
(a) you could give us some rapid information about the orchard and how bad the problem is; we are trying to work out UK-specific risk factors. Please use this form (or the QR code below).
forms.office.com/e/N3zFGvcMnr
A QR code leading to a form: https://forms.office.com/e/N3zFGvcMnr (it asks questions about orchards with apple blossom weevil)
April 29, 2025 at 9:26 PM
sejarnold.bsky.social
We want your apple blossom weevils!

Are you an apple orchard grower or apple agronomist in the UK?

We are looking for capped blossom sightings in UK orchards, and a bit of information about the locations where you are finding them.

#IPM #AppleOrchards #AppleBlossomWeevil #Horticulture
A fairly close-up view of the tip of an apple branch, with green leaves and a flower bud that is shrivelled and brown because it contains a weevil that has damaged it.
April 29, 2025 at 9:25 PM
sejarnold.bsky.social
Finding identification of this caterpillar to be harder than anticipated! Thought it'd be a quick job (is there a comprehensive resource that categorises most UK caterpillars by appearance?) but not that quick.
Location: Kent, UK
Foodplant: Comfrey (Symphytum)
#InsectID #WhatsThatCaterpillar
Human hand holds a leaf (about 4-5cm long?) on which a smallish caterpillar (1-2cm long) feeds. Caterpillar is black with an orange-brown dorsal stripe and white dots along the side, with various clumps of hairs sprouting. Leaf is comfrey, so a bit hairy and quite soft.
April 5, 2025 at 9:10 PM
sejarnold.bsky.social
5. Smart and sustainable pest/disease management
Cocoa suffers from lots of pests & diseases.

Integrated pest (& pollinator & disease) management is the principle of taking a more thoughtful approach to managing crop pests...

#IPM #SustainableAgriculture #PestManagement
Cocoa solutions: sustainable pest management Synthetic pesticides (crossed out) - reduce and replace these! Use: (in order of preference on an IPM pyramid, from bottom (better) to top (less preferred) Habitat management - usually healthy, biodiverse habitats resist pests and disease better (image of a plant-rich agroforestry cocoa farm) Trapping and monitoring - detecting pests early means controls will be more effective than leaving it too late (image of a yellow sticky trap in the field) Biocontrols, biopesticides - some nematodes and fungi control pest insects. Some plant extracts kill pests (image of a nematode and a fungal growth under microscope) Larger stylised image of a cocoa tree, with an inset image of white, fluffy insects (mealybugs) feeding on a branch
March 13, 2025 at 2:11 PM
sejarnold.bsky.social
4. Pollinator management
New evidence shows that cocoa productivity is really being limited by poor pollination. To increase this, one route is natural pollination - providing what insects need to breed and thrive, so they can do the work. We think rotting cocoa pods are important...
Infographic shows two options: manual and natural pollination Manual pollination (with a pair of human hands holding forceps to demonstrate this on a flower): gives high yields but trees need to be kept healthy, and it takes takes skill. Image to the left shows a tree very heavily laden with pods, that has been hand-pollinated Natural pollination: is it possible to breed pollinators on the farm? Research is working on this. Protecting natural pollinators: reduce pesticide use, provide habitat and breeding materials that stay moist in the dry season (images of a plastic insect tent on the farm with materials for pollinators to breed in, a pile of cocoa pods on a farm, and a close-up of a midge pollinator).
March 10, 2025 at 9:37 PM
sejarnold.bsky.social
3. Managing soil health
The soil on many cocoa farms is in poor condition. But many of the interventions that support healthy ecosystems also help soil, like use of shade trees and intercrops. Products like biostimulants can improve soil health and crop-soil-microbiome interactions.
Cocoa solutions: caring for soil. Fertilisers - synthetic or organic - based on evidence of the crop's needs Other soil amendments include beneficial fungi and plant extracts that support crop health Biochar may improve water retention and reduce erosion Increasing shade trees and plant diversity reduces runoff and erosion
March 10, 2025 at 9:31 PM
sejarnold.bsky.social
2. Smarter water management.
The most hi-tech cocoa farms use irrigation to ensure cocoa is not drought-stressed during increasingly erratic dry seasons.

This is harder for remote smallholder farms - you can't irrigate unless you have a water source.
Cocoa solutions: Smarter water management The right irrigation for the farm: - drip - solar-powered - river or borehole? Cycle showing cocoa flowers, pods developing in dry season and harvest, then rains arriving before it flowers again. An arrow leads to the question: Can suitable irrigation here (dry season) support sustainable yields and reduce crop loss? Additional benefits for moisture loving pollinators? Images show cocoa trees, irrigation lines and solar panels.
March 10, 2025 at 8:40 PM
sejarnold.bsky.social
1. Agroforestry - including dynamic agroforestry. Some countries (e.g. parts of Brazil) have long traditions of shade-grown cocoa under either natural forest canopy or alongside native or economically-useful shade trees (fruit, medicines, timber, firewood, etc.).
Cocoa solutions: (Dynamic) Agroforestry Cocoa trees alongside: - fruit trees (e.g. mango, papaya), - banana or plantain, - shading timber trees Provides different forestry products More complex environment = fewwer pests and diseases, more resistance to drought, flooding, heatwaves Image shows a stylised cluster of cocoa trees interspersed with other non-cocoa trees, including banana, shaded by a large tree that projects above the main canopy
March 10, 2025 at 8:36 PM
sejarnold.bsky.social
6. Deforestation
If cocoa farms become less productive and are not supporting the cocoa farmers' livelihoods, there is a risk that farms will expand - possibly into natural forest areas. New EU directives seek to reduce this. Good management should get more yield from the same land footprint!
Cocoa challenges: Deforestation Many cocoa dfarms have low/declining yields - same land, less income Sketch of cocoa farm adjacent to forest Cocoa farm expands into forest Sketch of the same cocoa farm and forest, but chunks taken out of the forest and converted to farm Areas of forest gradually lost Solution bubble: Sustainable improvement of yield from the same land area means less need to expand. Better data collection allows us to map farms' boundary changes
March 7, 2025 at 4:35 PM
sejarnold.bsky.social
5. Pollination
It's common for fewer than 5% of flowers on a cocoa tree to be pollinated under normal conditions. We still have big gaps in our understanding of cocoa pollinators & their needs. They may be threatened by drought, overuse of pesticides, & loss of breeding habitats.
Cocoa challenges: Pollination Image showing cocoa flower cluster Many cocoa varieties need pollination or they will not produce pods Option 1: Natural pollination. Midges, other insects. Threats: Climate change, pesticide use, farm management Images show two small insects highly magnified, a midge and a parasitoid wasp. Option 2: Hand (manual) pollination Image of a human carrying out hand pollination of cocoa with forceps. Drawback: costly, difficult, time-consuming. Pollination is a problem for all cocoa-growing regions. Solution bubble: Better understanding of the most important/effective pollinators, creation of habitat, reduce toxins in environment
March 7, 2025 at 4:30 PM
sejarnold.bsky.social
4. Drought
Among all the cocoa experts we talked to in Brazil & West Africa, climate change was mentioned often, & especially how it affects rainfall patterns.

This can mean: dry seasons are longer/more intense, wet seasons come early, late or erratically, & continue for longer, or end too soon.
Cocoa challenges: Drought Late rains can delay or prevent the cocoa trees flowering, and also there may be fewer pollinators. A cycle shows rains arriving, cocoa flowering, pods developing, then during the dry season, harvest occurs. Annotations explain that yields will be lower in drought years, and in extreme drought, trees can drop leaves and forest fires become more likely. The solutions bubble explains that better harnessing of nature, via agroforestry and soil protection, can help. Affordable and sustainable irrigation, and breeding drought-tolerant varieties also helps.
March 7, 2025 at 12:27 PM