Behind the Moth Meme

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Unless you’ve digitally cleansed your life recently, you’ll probably be aware that moth memes have taken over the internet – so much so that there is now, inevitably, a Reddit page dedicated to this unique sub-group of social media fodder.

The focus of this frenzy of meme-making has been moths’ famed love of artificial light. But here at Mastering Entomology, we’ve decided to delve a little deeper.

First and foremost, though, it’s worth pointing out that there are plenty of moths that fly during the day – so aren’t the types to be suckered into the seductive glow of a lamp. A study by Florida Museum of Natural History suggested that 15-25% of all Lepidoptera are day-flyers, while Butterfly Conservation has helpfully produced an overview of the UK’s non-nocturnal moths.

But of the nocturnal species, is there really a deep craving driving moth orientation towards our light sources? The fun-killing simple answer is probably no. The expert consensus seems to be that it’s all a misunderstanding; that they’re actually looking to orient themselves by the moon, and they’re simply drawn to alternatives because they’re brighter. As they move closer, their ability to triangulate is thrown off kilter, resulting in them returning to the light repeatedly.

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But given the distraction, as opposed to attraction, our light sources bring, are all moths equally likely to zone in on the bright lights, and are all electric lighting types equally likely to bring lepidopterans into their glow? That’s another no and no.

The tendency to head for the light could be greater for moths from areas with little light pollution. Altermatt and Ebert (2016) found that in the case of the small ermine moth (Yponomeuta cagnagella), ‘city moths’ from populations that had experienced high amounts of artificial light were less likely to fly to light under lab conditions than those from ‘dark sky’ populations. It has been suggested by several studies that natural selection should favour those less drawn to artificial light – pretty logical stuff – and this research provides some evidence that such selection may indeed be happening.

Altermatt and Ebert have serious form when it comes to advancing knowledge on moths and light. In their 2009 study with Adrian Baumeyer, male Yponomeuta cagnagella and Ligdia adustata were seen to be 1.6 times more likely to make a beeline for an artificial light source than females. A good argument to settle the ‘smarter sex’ debate, perhaps.

A PhD study in Exeter has recently shed further light (pardon the pun) on the type of illumination most attractive to larger moths, finding that short wave lighting attracts both greater numbers of species and individuals than long wave.

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The interplay of moths and light is, alas, not all online laughs and levity. There is growing evidence that artificial light may be having deeper effects on moth numbers than simply the deletion of those flying at speed towards the lamp. While the fact they are drawn to light is firmly established, there is evidence that it could be reducing moths’ attraction to each other.

A 2015 study in the Netherlands by van Geffen et al looked at the mating habits of Operophtera brumata, a member of the Geometridae family, when tree trunks were lit with different-coloured LED lighting. What the first phase of the research discovered was two-fold, and fascinating: a significant reduction in females on the illuminated trunks, again suggesting a sex bias in light attraction, and an inhibition of mating when they were under the lights. A side note, though: perhaps appropriately for this sexy moth discussion, more females caught on trunks lit with red light had mated than those with green or white light.

Mating is not the only matter that will pique concern amongst conservationists. Other research has found links between feeding and artificial light (they appeared to do less when subjected to it) and caterpillar development (they reached lower mass under white light and pupated earlier under green and white).

There is clearly multi-faceted interplay between moths and light, and a sense that we’re only beginning to understand the mechanics and effects of it. The ability of species to coexist with increasingly dense human habitation is a hot topic, so knowledge in this area is only set to grow in the coming years. Far from every aspect of this issue has been covered in this blog, but in the interests of brevity, it might be best to wrap up (although most of those readers who came for the memes have probably gone already).

Final note: this week and next we’re doing the taught elements of Biology and Taxonomy of Insects, the second module of the Entomology Masters here at Harper. Next Wednesday we’ll be looking at Lepidoptera, increasing our knowledge of these complex yet internet content-friendly insects.

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Meet the new ento-blogging team

New year, new team of aspirant entomologists writing for Mastering Entomology – and this time around there’s four of us. With no further ado, let’s introduce the team…

Ant lion

Here’s an antlion Sam found earlier

The antlion fanatic

Hey, I’m Sam. I’m actually a fairly recent convert to the ento crowd. My undergrad was in zoology, where I was considering going into conservation or behavioural research. As the leader of the course was an entomologist I did learn a lot about insects, but my passion wasn’t really ignited until a trip to Africa in my final year. In a place where monkeys and hippos are the norm, I found greater fascination in the intricate pitfall traps formed by the antlions that surrounded our hostel. That trip cemented in me a desire to understand the behaviour of insects and its evolution. Which is exactly why I’m here at Harper Adams. I’ll try my best to share all the interesting behaviours that I come across in my studies.

The future curator

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…and a death’s head hawkmoth Dom photographed earlier

Hi, I’m Dominic. I chose to study Entomology as I am very passionate about the subject and want to improve my knowledge and understanding of Insects. Ultimately, I wish to work as an Entomological curator where I can look after the important collections held within museums, educate the public on insects and hopefully conduct my own research to help the conservation of entomofauna and the habitats they reside in. My main interests in Entomology are Lepidoptera and Coleoptera (predominantly Moths and Scarabaeidae). I am fascinated with the way that Insects interact with and influence other organisms as well as looking at their roles in various ecosystems, I am also intrigued with how Insects have impacted human culture. In this blog I hope to write about insect behaviour, interactions, historical importance, environmental impacts and any other Entomology facts I find interesting.

 

Entomologists on wrekin

Gary (L) on a collecting mission with fellow members of the Harper ento crowd

The outlier

I’m Gary. You could certainly argue that I’m not the typical Entomology MSc student, having spent the last decade-plus in writing, communications and journalism. The love of insects has always been there, mind – just, it’s fair to say, lying somewhat dormant for a spell. Heavily influencing my taking of this somewhat tangential turn was time spent in the Prespa National Park in Greece, Albania and the Republic of Macedonia, where, similarly to Sam, I spent much of my time staring in awe at the biodiversity on the floor rather than looking out for bears, wolves or the magnificent array of bird species. Though I’m not exactly relishing the statistics that are to come as we work towards our final research projects, an insect-collecting trip up the Wrekin last week with some of my fellow Ento postgrads firmly fixed in my mind that I’ve made the right, albeit slightly curious, decision. Twitter: @garyfromleeds

Niahs aphid

Niah’s pet aphid mama

The pest patroller

Hi, I’m Niah, the token Integrated Pest Management student on this blog. I come from a science background, having just completed my Bachelor’s in Biological Science, but I knew next to nothing about entomology until my interest was sparked on a placement at the Warwick Crop Centre. Having spent a summer emptying traps, carrying out pesticide trials, and compiling citizen science moth counts into a report, I decided that pest management was the way forward! As well as singing the praises of biological control, I am especially interested in social insects, months, vectors of human disease and, of course, aphids. It’s quite a mixed bag but I’m looking forward to including some of them in this blog!

We’re aspiring to bring you some blog content that’s as diverse and intriguing as the world of our favourite arthropods. If we can get even remotely near, we’ll have done a pretty good job.