Max Anderson

[Max Anderson]

Small Copper

Late last year, the back garden became an incredibly useful place for me to become more familiar with Small Copper. They had occupied a south-facing slope into which I had plug planted some Sorrel.

There were at least 4 adults present, and I had a constant supply of eggs and caterpillars that meant I was busy during the late afternoons in September. I had such impressive numbers, that I was finding two or three caterpillars on some leaves, and over 50 eggs across the 6 plants that I had. The eggs are often laid on either the upper or underside of Sorrel leaves, or on the stems. On the leaves, the eggs are most often laid towards the edge, or along the midrib. I noticed that there were a few examples where the female had chosen to lay eggs near feeding damage, potentially because of the edge that is created by this.

I've been curious about where the caterpillars choose to pupate, and I surrounded two of the occupied Sorrel plants with dead leaves, in the hope that I might entice one of the wandering caterpillars to pupate on them. The vast majority disappeared, presumably to pupate somewhere dark and safe, close to the ground. I was surprised to find that one caterpillar took a liking to the dead leaves, which I kept track of for a few weeks until it emerged.

[Max Anderson]

White-letter Hairstreaks

Since discovering this species for the first time in my local town in East Devon last year, I’ve been quite busy. Last July, I saw some adults on a young Wych Elm in the local park, and crucially, I spotted a female laying eggs. In the early winter, I counted 11 eggs after carefully searching every accessible branch of the tree.

For the next few months, I aimed to cover as many streets, parks and green spaces that I could during any of my runs, to map out any potential Elm trees to search for caterpillars in the spring. By early February, the eggs on the Wych Elm had begun to hatch, and after a few weeks, on a sunny late-winter day, I was able to find some second instar caterpillars on the buds, as I had done last year.

When other Elms finally began to come into leaf in mid/late April, I shot out to see what I could find with the UV torch. Over the course of 3 or 4 nights of surveys, I tallied 24 caterpillars at across 6 brand new sites in Exmouth. It’s truly remarkable how powerful UV torch surveys are. I anticipate that this species is far more widespread than we currently understand it to be, but the elusive nature of the adults means that they’re significantly under-recorded.

I’ve also been able to track a number of caterpillars through to pupation. One particular English Elm hosted 9 caterpillars, 6 of which pupated on the underside of leaves, or branches. My previous experience of WLH in Brighton has taught me that the caterpillars often just disappear, as many of them wander off to find somewhere appropriate to pupate. I’m aware they they either pupate on the leaves, fissures or cracks of the trunk, or on the ground, but I’m curious to know what makes them decide where would be best to pupate.

A few days after pupating, one of the pupae had attracted some attention from ants. I watched for a few minutes as the two ants investigated the pupa, touching the same area that the Newcomer's gland is situated on larvae. I'm not too clear about of any known records of myrmicophilous behaviour from WLH pupae, but I wouldn't be surprised if there was something going on!

I’m in the process of getting the local and county councils around the table to get some more planting of disease-resistant Elms in the area. We’ve been cutting down Elms for the past 50 years, and doing nothing to replace them. It’s about time we did something about this, otherwise we risk losing a whole host of species that are reliant on them.

[Katrina]

Very interesting report and well done for trying to get some more elms planted

[David M]

Fantastic finds, Max, and many thanks for sharing them.

I wish you all the best regarding your attempts to reverse the loss of local elms.

[selbypaul]

Really interesting Max. Which UV torch are you using? I'd be interested in doing something similar here in Sheffield.

We have a suburban colony of White Letter Hairstreak on a 120 year old Huntingdon Elm street tree that I saved from unnecessary felling. But I've always suspected small sub-colonies nearby on smaller elm trees, but never been able to prove this.

[Max Anderson]

Thanks all!

Paul - I'm using a 365nm UV torch. It's pretty powerful, which is helpful for finding things at a further distance now and again. If you don't already have a torch, I'm sure a decent 365nm UV torch with good reviews online will do the job and help to confirm if the WLH are in your Huntingdon Elm! It's remarkable how easy it makes looking for WLH.

[selbypaul]

Thanks Max, really helpful! Look forward to buying one and trying it out next spring!