The Explanation of the Strange Insect Behavior: Being Drawn to a Flame – Video

The Explanation of the Strange Insect Behavior: Being Drawn to a Flame – Video

The mysterious behavior of insects being drawn to light, like moths to a flame, has puzzled scientists and intrigued casual observers for centuries. However, recent advancements in camera technology and research methods have shed light on this strange phenomenon. Researchers have discovered that flying insects, such as moths, butterflies, and even dragonflies, exhibit a behavior called the dorsal light response when approaching artificial light sources.

By tilting their backs towards the light, insects become disoriented in 3D space and find themselves trapped in a loop, circling around the light source. This behavior can have detrimental effects on insect populations, as many are unable to escape and ultimately crash or stall in flight. Understanding this mechanism not only solves a long-standing mystery but also has implications for conservation efforts to protect these essential pollinating and ecosystem-essential insects.

Further research is needed to explore the ecological impact of artificial light on insect populations and develop strategies to minimize the negative effects. By unraveling the secrets of why insects are drawn to light, we may be able to create lighting environments that are safer for these vital creatures.

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Video Transcript

VOICE OVER: If you’ve turned on a light  outside at night, you’ve probably seen this. SAMUEL FABIAN: As soon as humans started  lighting fires or creating light at night,   they noticed that seemingly suicidally  insects would dive into them or kind of  

Emerge out the night and cluster around  these light sources, and we wondered why. VO: Previous explanations have included  insects using the moon to navigate,   or simply being drawn to the heat  given off by incandescent bulbs. Now though advances in camera technology are  allowing researchers to study the flight of  

These insects in more detail than ever before,  and this group have made a key discovery. Flying insects seem to be twisting to  keep their back to the light. Rather   than being attracted towards it, they find  themselves stuck in a loop flying around it.

Have these experiments finally answered the  question – what draws the moth to the flame? VO: Moths’ attraction to light is well known  enough to have inspired a commonly used phrase,   but it’s not just moths that are  attracted to artificial lights.

SAM: If you’re stood by a light at night,  and you see something batting around,   it’s probably not just moths, there are  flies, there are wasps, there’s any number   of different insects. Basically any insect  that can fly, more or less, is going to end  

Up at lights at night. It just so happens that  a whole bunch of insects rarely fly at night,   and so an example of that would be the dragonfly,  we we we tend not to think about dragonflies   coming lights at night, but actually it  turns out if you get a dragonfly to fly,  

At night, it ends up circling around  the light just like your moth does. VO: And even though this behaviour is very  common, explaining it has proven tricky. SAM: The real problem is that insects move  really fast for their body size. So when you  

Film it turns out as a little blur even under  quite bright light and then you take that at   night where you have to use infrared lights in  order to illuminate the insect but not have it   see the light, it’s only been recently that we’ve  had sensitive enough cameras to allow us to film  

Insects at night, at speeds that then allow us to  see what the insect is actually doing in the air. VO: The team attach reflective markers to the  insects’ bodies. Then, eight motion capture   cameras allow them to track its exact position  and orientation at 200 frames per second.

SAM: The camera can detect these  little markers on the backs of   the insect and we can get a really  accurate read on exactly where it is   in space and actually we can tell  the orientation in space as well. VO: As well as this lab data, the  team made observations in the wild,  

Under more natural conditions. SAM: Either in our back gardens filming things  or traveling down to Costa Rica in order to film   large numbers of different kinds of night  flying insect around light sources. That’s   where we’re using high frame rate cameras under  kind of constant infrared illumination to record  

Insects traveling around light sources  and that come to light sources at night. VO: Together these data revealed exactly what   was happening as the insects  approached a light source. SAM: What we kept finding is that  insects such as dragonflies, moths,  

Butterflies and other night flying insects as  well, were tilting their backs – uh which we   call the dorsal axis – their dorsum towards  the light. And this matches onto a response   we’ve known about for quite some time in fact,  it’s been written about in the literature for  

Probably about the last 100 years, and  that’s called a dorsal light response. VO: This so called dorsal light response has  been described for some time in insects and fish,   and is believed to be used to help them  orient themselves when moving in 3D space.

SAM: It’s quite strange for us to think  about this because as animals that spend   most of our time on the ground it’s quite  obvious which way gravity is, but actually   if you’re flying you’re pulling all kinds of  g-forces and those g-forces or accelerations  

As you’re moving around can kind of mask exactly  where true gravity is especially if there’s some   sort of big aerial turbulence that hits you, you  want to very quickly work out which way is up. VO: And before humans and  their lightbulbs came along,  

Looking for the relative brightness of the  sky compared to the earth was a good way of   finding up. So insects tilt their backs  towards the brightest area they can see. SAM: That means that all of their  flight forces they’re producing,  

The lift is they’re not pointing in the  right direction for them to continue flight,   they’re going to start curving. And so that’s why  we see them circling, and not really spiralling   in, cruising around and round and round and  seeming completely stuck and unable to leave.

VO: And this isn’t the only problem this  simple reflex causes insects around lights. SAM: If we give them light from beneath we  actually see that insects totally invert   themselves and flip upside down, and that  obviously is not a good way to get about at  

Night because they then crash straight on into  the ground, and that’s probably why if you have   light shining on a kind of patch of floor you  tend to get insects sort of plummeting out of   the darkness straight onto that floor. They flip  themselves upside down and crashed, and we also  

Get stalling which is where insects that are  flying away from the light begin to pitch up,   pitch up, and they’re then at not producing  enough flight force to maintain the climb that   they’re attempting to do and that causes them  to slow down and tip onto new flight courses.

VO: Other explanations for this behaviour  that have been put forward over the years   don’t seem to match the new  observations.. The insects in   this study weren’t attracted to heat –  nor were they keeping the lights at the   same angle relative to their body as they  would if trying to navigate by the moon.

So is this case closed for the  mystery of the mesmerizing effect   of artificial light on flying insects? Not quite… SAM: There are several species of night flying  insects that we don’t find at light traps and  

I really want to get hold of those because I want  to see whether or not they still have this dorsal   light response. Because if they’re not using  light particularly to work out which way is   up and we know that they’re flying near lights  but don’t ever seem to get entrapped that’s a  

Very strong link to draw that it is really this  behavioral phenomenon that leads to all of these   insects coming to light at night, because we  cannot yet say absolutely this is the only   influence of the light on the insect while it’s  flying around there may be additional factors.

VO: This study only looked at insect  behaviour within a few metres of a   light source, but what happens  when insects are further away. SAM: We’d like to ecologically contextualize  this behavior of coming to light and determine  

Exactly what the kind of capture radius around  a light source would be at night and how it   affects insects that are doing different tasks  around an ecosystem. So whether that be foraging   over flowers or whether that be migrating  at high altitude directly over overhead.

VO: And understanding this mechanism doesn’t  just answer an age-old question – it could   lead to new ways to preserve and  protect these flying insects. SAM: How could we change lighting environments  to not trap insects because we’re facing a  

Massive decline in insects around the world  and artificial light at night is one of the   factors that could potentially be leading to  this decline. So only through understanding   the actual mechanism that causes insects  to get trapped around light can we begin   to understand how we could prevent them  getting trapped around light sources.

Video “‘Like a moth to a flame’ — this strange insect behaviour is finally explained” was uploaded on 01/30/2024 to Youtube Channel nature video