Max Anderson

[Max Anderson]

Catching up

I’ve accumulated a few things over the past few months that I thought may be worth sharing.

White-letter Hairstreak

Here in East Devon, we have very few records of WLH, despite there being some Elm here and there. I recorded the first ever WLH in my town during the winter, when I found 5 eggs on a reasonably small, unassuming Elm (Wych – I think!) in a nearby park. These eggs hatched around the last weekend in Feb, and I managed to find a single L2 larvae in mid/late April. At this time, the leaf buds were about 2/3 weeks away from opening, and so the larva found a comfy spot and sat in wait for about 12-16 days. When the leaves finally emerged, the larva disappeared and began to feed into their remaining instars. It wasn’t until the leaves had fully unfurled that I was able to find other larvae further up the tree, coming to a highest count of 8 in one night on the one tree. I’ve been curious about pupation in WLH for some time, and I’ve struggled to find any pupa in the last 3 years of studying them. The local Elm here is rather small, and I found a larva pupating on the underside of an Ivy leaf towards the base of the tree. Everyone suggests that they either pupate on leaves, in crevices/fissures on the tree, or in amongst leaf litter on the ground, but I do wonder what triggers their decision making about pupation site.

[Max Anderson]

Purple Hairstreaks.

Luck has it that less than 50m from the Elm, is a magnificent Turkey Oak, where I came across 4 second instar larvae on the lower hanging branches. These were another first for this area, without a record of PH until this year. I lost patience in searching for PH eggs on these oaks long ago, and didn’t find a single one – praise be to the UV torch. The thinner and leggy leaves of Turkey Oak sit on longer stalks than Pedunculate/Sessile Oaks, which I believe makes them better suited candidates for observing PH larvae. During the day, the larvae nestled themselves in amongst the dense material at the base of flowers and leaf stems, where they meet the branch. From here, they venture out onto the underside of the leaves and begin to feed from the end of the leaf, working their way back down to the stem. Interestingly the larvae do not fluoresce under 395nm UV torches; only the 365nm torch does the trick. These larvae disappeared shortly after 15th May, and I had no luck in finding any larvae or pupae after this date. As with WLH, the suggestion is that they pupate on bark or the ground, but I was unable to find any, despite searching branches and the base of the tree twice, quite thoroughly.

[Max Anderson]

Holly Blue

The alley down the side of my house is a good sun trap for butterflies, where they patrol the Cherry Laurel and Ivy hedges looking for action. Amongst the Speckled Woods, Brimstones and Large Whites are some boisterous Holly Blues, which leap into action when disturbed. Just outside the house, there’s a few Holly bushes protruding from the hedge, which I noticed that females took a fancy to this year. They laid a fair few eggs on the fruits in early May, and I’ve been monitoring them since. The larvae emerged about 12-16 days later and they’re currently in their second instar (6th June). I anticipate that they’ll moult soon-ish. It’s been interesting to observe their feeding behaviour, as they create perfectly circular holes in the fruits and sit on top with their head stuck in. If we talk about interesting and under-appreciated species, I think this one might come towards the top end of my list.

[Max Anderson]

Silver-studded Blue

Another local species for me, just a few km away from home. A few weeks ago, I met up with Marcus Rhodes - a PhD student at Exeter Uni, working on butterflies and how they respond to microclimatic variation. He’s done some incredible work on SSB, and I wanted to learn more about them from him about the ecological requirements and preferences of this species, as well as site management.

I took him on a whistle-stop tour of the Pebblebed Heaths in East Devon, and I found my first larvae being tended to by Lasius ants. When we talk about ‘getting our eye in’, I think this has never been more important than when looking for SSB larvae. Suitable habitat here is where food plants are present, the sward is short (<10cm), with ample bare ground (perhaps 10-50%) and Lasius ants are present. The eye has to pick up on ant activity, but a very specific type. When there’s a SSB larva present, they congregate in groups, often 10+ indviduals and behave slightly more frantically than normal, and not quite as frantic as when you disturb them. Tuned in on this, you’ll give yourself a better chance – though there’s never any guarantee. It may be that the ants have found some food, which triggers a similar level of activity to when they’re with a larva.

I also picked up a new trick - carry some chopsticks/wooden skewers with you. You can use them to poke aorund the prickly vegetation, and even use them as ground markers if needed - Genius!

On 5th June, I set out to see if I could find any pupae in areas that are reported as having higher densities of adults in the last few years. Thanks to the advice given by Marcus, I was able to find 3 pupae in about 20 minutes, all within 20 sq m area. They occasionally pupate beneath rocks, which get nice and warm during the day, while offering good protection. I’m sure there are already adults on the wing here, but I haven’t yet seen one.

Marcus in the field

[Max Anderson]

Heath Fritillary

Back in April, I went out to Hawkcombe wood in Exmoor to survey HF larvae, which bask on leaves during sunny weather. When we arrived, it started to rain and hail, and it didn’t stop for some time. We persisted and looked for larvae amongst the leaf litter, and weren’t disappointed. A total count of 39 larvae in about 1hr of searching between about 8 people. Most of the larvae were a fair bit behind where they were at this time last year, perhaps one or two instars behind.

I had a request from Dan Danahar to find a HF pupa for a film that he’s putting together on this species. I promised that I’d try, and spent a day towards the mid/end of May looking for one on Exmoor. After 4 or 5 hours, I had only found two caterpillars and nothing else. Unfased by the lack of success, I returned a week or so later and managed to find a single pupa in amongst some bracken litter. Remarkably hard to find, but persistance can occasionally pay off.

[Max Anderson]

Marsh Fritillary

A week or so ago, I was invited to visit a site on Dartmoor to survey Marsh Fritillary. There were reports of exceptional numbers in the good weather we were having, and I had high expectations. Unfortunately we arrived in overcast weather, and other than a stunning peacock, we only ended up seeing 5 male MF on the wing. Despite covering a substantial amount of ground, we didn’t disturb a single adult from their resting spots until the weather began to pick up slightly. They must really nestle themselves into the vegetation in sub-optimal weather. As I walked through the site, I was vigilantly searching amongst the vegetation and came across a few adults caught in spider webs. I also came across a single pupa, nestled in some long grass. On my way back to the car, I also managed to find some Orange-tip and Brimstone larvae posing nicely. Fingers crossed I can get back up to this site again soon, when the weather is nice.

[Pete Eeles]

Absolutely superb reports, Max! I love the SSB insights and would never have thought of chopsticks being a useful butterflying tool!

Cheers,

- Pete

[Benjamin]

It’s clear how much time you’re dedicating to field studies of immature stages Max, and it really does make for excellent reading. Looking forward to seeing what you come up with next……

[Padfield]

Fantastic reports. I’ve learnt so much from them. I’ll check the rating of my own UV torch; I’ve searched in vain for purple hairstreak cats and always assumed it was because there were none there. Maybe I just need a slightly shorter wavelength.

Guy

[Pauline]

Excellent reports Max with images to match. Makes me feel quite inadequate as I've been looking for SSB larva on my local site without success.

[David M]

First class reports, Max, with pin-sharp images supporting them.

Thoroughly enjoyed reading them all. Many thanks for sharing.

[Vince Massimo]

Great stuff, Max
Could you check your private messages next time you log in please. I am after some site information for the Species Albums.

Cheers,
Vince

[Max Anderson]

Thanks all - glad to know that my reports can proivde some value!

Guy - Yes, i think it might be worth trying a 365nm torch if you don't already have one.

Pauline - Don't dispair, it takes a lot of time to get your eye in on SSB larvae. I was fortunate to have a head start thanks to the excellent guidance from Marcus..

[Max Anderson]

Silver-studded Blues

Here in East Devon, adults began to emerge on or around 6th or 7th June, and by the 15th, multiple females were out on the wing and mating pairs were popping up around every corner. A 30 minute walk through the few areas of suitable habitat yielded 18 males, 9 females and 6 mating pairs. After finding a good number of eggs on Bracken pinnae in the winter, I decided to sit and wait in the area that produced the highest density of eggs in the hope that a female would pop over. Didn't take very long, as after about 10 minutes, a female came along to test the pinnae for suitability by probing the underside of the fronds with her abdomen. I do wonder what exactly takes their liking about the specific locations that they end up choosing. I'm not so convinced that they're being all that picky, given that they often drop their eggs off on any substrate that happens to be near ants. I suspect that some of the 'probing' behaviour may serve as a mechanism to prepare the egg for laying, rather than detecting the suitabiity of the location. After she had laid the egg and shot off, I turned the pinna over and watched as the green egg turned the pearly-white colour in about 30 seconds (my pictures of the eggs arent too great, but they do show some change in colour).

[Max Anderson]

Large Blue

There's a certain charm about arion that I can't quite shake off. This post is nothing more than an indulgance - I hopped over the border to spend some time with the Large Blue in their peak. Plenty of adults on the wing and a great afternoon spent with the camera. These in-flight shots take an exceptional amount of patience and practice. My hit rate is still very low, but it's getting better, albeit slowly.

[Wurzel]

Cracking set of Large Blues Max - especially the in flight shots

Have a goodun

Wurzel

[David M]

It's plainly clear how much time and effort you put into these studies, Max. I feel almost ashamed (as someone who puts in only a fraction of that effort) to have the good fortune to see the best of your images in such a user-friendly way.

I think you have earned as much 'indulgence' as you like.

[Max Anderson]

Holly Blue

Following on from the observations I made on Holly Blues during May/June last year, I continued my efforts in September 2023, by monitoring them and the Ivy by my house. The caterpillars are quite conspicuous while feeding on the Ivy buds, as they stand out against the round heads of the buds.

I was impressed to count a whopping 86 Holly blue caterpillars on Ivy across two nights of UV surveys along the 50m strip of Ivy along the path near my house. I was also interested to find only 2 of those were variants with pink dorsal and lateral stripes, which are similar in appearance to some Small Coppers. I know that the Holly Blue can be quite variable in it’s appearance as a caterpillar, particularly in relation to the foodplant that it occupies.

After a crazy-good year for Holly Blue last year, this spring has been pretty quiet, though I had an early female doing some egg-laying on the Holly in the front garden. The caterpillars are already out and have been busy for some time. They leave some quite distinctive feeding holes on the fruits of Holly, which are perfectly round and often covered in a silk-like material.

[Max Anderson]

Black Hairstreak

Despite living in Devon, I managed to grab a few opportunities to spend some time with Black Hairstreaks this year, starting with a visit to Sussex in January.

Although I’ve already made it very clear that looking for pruni eggs can be an extremely difficult and largely insane task, I had nothing better to do with my time than just this when I had a day to spare during a long weekend over in Sussex at the end of January.

A four hour search yielded 5 eggs in 4 hours (much better than I’ve done before). I know that there are still some questions about the preferred locations for egg-laying, as we don’t really have the data to be sure about this. On my growing list things to address is one which involves identifying the characteristics of plants that are occupied by caterpillars. This would help to be more specific about the conditions of plants that are preferred for egg-laying, and we could even search those occupied plants for the remains of eggs to look at where on the plants the females choose to lay. Quite a lot of work to do, and not something I can do while I’m living in Devon!

[Max Anderson]

Black Hairstreak continued…

As well as my trip to Sussex in January, I squeezed in a visit to Bernwood Forest on the Oxfordshire/Buckinghamshire border on 10th May for some BC volunteers to do some UV surveys for Black Hairstreak caterpillars. We tallied an impressive 83 caterpillars in about 1.5 hours, and I hung around until the early hours of the morning and found another 38 in 30 mins. Bernwood was also nice place to be for us to appreciate the Northern Lights.

Most of the caterpillars were getting ready to pupate, but I still found a few earlier instars around. The morning after the survey, I returned to check some of the caterpillars, and discovered that a prepupa from the night before had pupated. We found the larvae as low as 0.5m and up to around 4m high along the dense Blackthorn hedges around the Forest. The majority were around 1.5-2.5m high, and they were also found on all aspects, not just the south facing hedges.

The UV survey method will surely prove to be an incredibly powerful tool for a number of species, but I think this is particularly the case for pruni. It’s incredibly well suited to surveys with UV torches, and it will help immensely in finding new sites, clarifying its distribution, monitoring population changes more accurately, and understanding its habitat requirements in detail.