What we're missing

Netelia cristata

Over the past few years I've tried (and pretty much failed) to convince colleagues that it is a scientific and ethical imperative to at least try to analyze the bycatch from insect trapping, including but not limited to light traps. Blinded by the light (sorry, moths), I can't seem to convince people to make the effort. One notable exception is my colleague Graham who regularly sends me samples from his amazingly productive garden moth trap. Working together we have clocked up an ever growing list of new species for VC55, including many solitary wasps.

Parasitoid wasps, usually overlooked, are crucial for understanding ecosystems and environmental change. Capitalising on other projects such as the bycatch from moth trapping can provide valuable insights into these overlooked taxa at relatively low additional cost or effort. A new article describes the use of an existing citizen science project, the National Moth Recording Scheme, to monitor nocturnal parasitoid wasps in the UK. The researchers collaborated with moth-trappers to collect "bycatch" from light traps, focusing on Ichneumonidae, a family of parasitoid wasps. Over five months in 2024, they collected 6,779 specimens, representing over 184 taxa. The project successfully collected a majority of previously recorded UK nocturnal Ichneumons within the five month period (e.g. 82% of Netelia, 91% of Ophion) and provided new species records for 67 of the 71 sampled species in 82 of 91 sampled vice-counties, including some rare species.
Cunningham-Eurich, I., Aucock, L., Walters-Hutton, B., Sumner, S. & Broad, G.R. (2026) Moth traps shine a light on nocturnal parasitoid wasps: Snapshot assessment of UK diversity and distributions. Insect Conservation and Diversity, 1–23. Available from: https://doi.org/10.1111/icad.70135

Plenty of research shows the effectiveness of UV LED trapping for a wide range of insect taxa, so as soon as it stops raining I'm aiming to use my newly acquired LED strings to figure out what's flying about out there in the dark.  

See also: Dietenberger, M., Jechow, A., Sann, M., & Hölker, F. (2025) Shedding light on dark taxa: exploring a cryptic diversity of parasitoid wasps affected by artificial light at night. Scientific reports, 15(1), 6237. https://www.nature.com/articles/s41598-025-88111-3

LED Evolution

I've been very impressed with the LED light strip I bought recently, so much so that I decided to convert my hulking great mains-powered ALS actinic Robinson trap to LED. This was simple to do (30cm of white ABS waste pipe, another 2 metre LED strip and a few cable ties - total cost under £15. A one hour test run on a cool evening proved it works - 5 moths of 5 species but a couple of nice ones I don't see in the garden often - a Red Underwing (Catocala nupta) and a Rush Veneer (Nomophila noctuella). I'm a thorough convert to LED moth traps. 

A moth trap in my pocket

Recently I was inspired by a Bluesky post from Andy Symes about his portable LED moth trap. I've been meaning to try this for a long time and this finally gave me the kick to get on with it. Andy's trap is the "classic" version using an IKEA collapsible laundry basket with a hole cut in lid, a cut-off plastic funnel, vanes (scavenged off an old moth trap but could make DIY ones) and an LED light strip. I've got my hulking great mains-powered ALS actinic Robinson trap but I find I'm using it less because of the hassle of dragging it all out, running the cable and setting it up, so I wanted something as portable (and cheap) as possible.  

Following Andy's lead, I bought a cheap waterproof 2 metre blacklight (395nm-405nm) LED USB light strip and powered it using a small old Duracell powerbank I had around. I put the powerbank in a ziplock bag and dumped the whole thing on an old (once white) pillow case, then gave it a 10 minute test run in the garden. 

 

I was delighted with the results - in no time it pulled in a good range of Coleoptera, Diptera, Hemiptera, Lepidoptera and Trichoptera. But the best bit is that it's cost me 12 quid and I can roll the whole thing up and put it in my pocket. It's not a moth trap as such as you can't walk away and leave it, but I'm hoping the sheer ease of use will encourage me to use it more often.

Diffusion Diffusion Diffusion

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I've written so much about theimportance of diffusion in macro photography and microscopy that I almost feel guilty about mentioning it again. Almost, but not quite. So here's a practical demonstration of how much detail is lost without adequate diffusion. 

Kalanchoe leaf, 100X.

 

Transformation

 

Last night I gave a talk to a local wildlife group which unexpectedly turned into a discussion about insect decline. It had to be said but that doesn't mean I like saying it. If you were in the audience, I apologise again. Seeking solace this morning, I visited my favourite wood. Over the last few years this has been depressing as Ash Dieback has gradually decimated them. Today I discovered that most of the dead Ash has been removed, and the transformation from dank Ash woodland into a very open, light-filled Oak woodland was startling and marvellous. 

 

Why flying insects gather at artificial light

Why flying insects gather at artificial light. bioRxiv, 2023-04. (2023) https://doi.org/10.1101/2023.04.11.536486 

"For millennia, humans have watched nocturnal insects flying erratically around fires and lamps. Explanations have included theories of “lunar navigation” and “escape to light”. However, without three-dimensional flight data to test them rigorously, this odd behaviour has remained unexplained. We employed high-resolution motion capture in the laboratory and stereo-videography in the field to reconstruct the 3D kinematics of insect flights around artificial lights. Contrary to the expectation of attraction, insects do not steer directly toward the light. Instead, insects turn their dorsum toward the light, generating flight bouts perpendicular to the source. Under natural sky light, tilting the dorsum towards the brightest visual hemisphere helps maintain proper flight attitude and control. Near artificial sources, however, this highly conserved dorsal-light-response can produce continuous steering around the light and trap an insect. Our guidance model demonstrates that this dorsal tilting is sufficient to create the seemingly erratic flight paths of insects near lights and is the most plausible model for why flying insects gather at artificial lights."

 

 

How to improve your microscopy

There's no doubt that microscope optics are important in forming a good image, and if you're going to record the output as a photo or a video, then the capture system and linking optics are important too.  However, I'm increasingly coming round to the view that the lighting is as important as the above.  It doesn't matter if you're using a fancy microscope and an expensive camera or a cheap microscope and holding your mobile phone to the eyepiece to take photos, if the lighting is working against you, then you're going to struggle. Like many people I've been using Ikea Jansjo LED lamps for microscopy. They're relatively cheap and they work OK, but it wasn't until I bought a Brunel Microscopes Dual Flexilite LED unit recently that my eyes were opened:



Using exactly the same optics, the quality of the images I can produce with my kit has improved 10-fold. Here's Dismodicus bifrons, a 2mm-long spider:



And here's the epigyne from this specimen, which is approximately 0.1mm:



I've never been able to produce images this good before. What has changed? Not the optics - only the lighting.

Upping my game

My standard setup for most microscopy is a stereomicroscope and an LED ring light (switching to a compound microscope if I need to). Stereomicroscopes tend to be optimized for depth of field rather than resolution. Ring lights tend to produce flat images with minimal shadows because the light is directly above the specimen. Put the two together and the images tend to be low contrast and muddy. Adding adjustable low incident angle spot lighting produces controllable shadows and therefore adds to the 3D effect of the image. I'm a big fan of the 10W Ikea Jansjö LED worklamps for supplemental lighting - they're cheap and convenient but they do have a few issues. They are a warm colour (somewhere around 3000 K) and since my ring light is more of a daylight spectrum (around 5000 K), it's difficult to produce images with accurate colour. Second, they have quite a wide angle of incidence and thus tend to produce quite a lot of scatter.

Today I took delivery of a Brunel Microscopes Dual Flexilite LED unit - big shoutout to Brunel, it arrived 48 hours after ordering. It's well made and for a piece of microscope kit, reasonably priced. More importantly, it's bloody good. Using the carefully angled incident light from this unit to supplement the LED ring light (same colour), the resolution is much better than the ring light alone and considerably better than using the Jansjö LED lamps. Sadly, the specimens I pulled out of the freezer to try it out on were both immature, but I'm very happy with the quality of the images.



A juvenile Metellina, which I strongly suspect is M. merianae, but I can't prove it:




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Gonatium rubens? Gongylidium rufipes? Hypomma bituberculatum? We'll never know! Don't worry about it and just admire the quality of the image!

(Click for larger image)