UnEarth Magazine.

Words by Lily Voyce

It’s not uncommon for flies, butterflies, moths, and a variety of other insects to find their way into my kitchen, particularly during the summer months, when we keep the windows open to let some air in and keep cool. But this summer we had a special visitor. First, I heard an unusual thud as a large insect appeared to hit the glass of the window. Upon looking around, I noticed the blur of a greyish moth and swiftly set about to capture and free it. After a few unsuccessful attempts, it was caught with a pint glass and paper.

Rather than clumsily fluttering like other moths and butterflies I’ve caught, this moth appeared to hover as it tapped against the glass. The moth had a rather chunky body and was mostly grey in colour except for some flashes of orange from under its wings. I took a few photos to help me identify it, then I set it free. To my delight, I discovered the moth was a hummingbird hawk-moth! These are summer visitors to the UK from Southern Europe and are mostly spotted in the south of the UK, but can occasionally be seen as far north as Scotland. Unlike other moths, the best time to spot hummingbird hawk-moths is during the day. They can often be spotted hovering next to a flower while they use their long tongues to drink the nectar. Their wings beat an amazing 80 times per second to maintain this hover, incidentally creating the characteristic humming noise that forms the reason for their name.

I, like many others, decided to log my sighting on the National Moth Recording Scheme (NMRS). The website is run by the Butterfly Conservation organisation and allows anyone to add their moth sightings to their database. They have over 34 million current and historic records of moths seen in the UK, and their database is used to increase understanding of moths and help their conservation. I was not alone in recording my hummingbird hawk-moth sighting as so far this year, they have received 1756 reports of hummingbird hawk-moths! In comparison, only 8 were recorded in 2021.

Using data collected through the NMRS, “The State of Britain’s Larger Moths Report” was published in 2021. In the UK, larger moths have been suffering; there has been a 33% decrease in abundance between 1968 and 2017. There has also been an observed increase in the northern ranges of many moths, with an average increase of 5km per year. The main driver of this is climate change. As the UK climate warms, moths can survive further North due to the conditions becoming more favourable. The warmer weather and strong winds are responsible for the influx of hummingbird hawk-moths this year. So, as the climate warms, we may see more and more of these visitors each year. In fact, over the past ten years they have already increased in distribution by 35% within the UK. Eventually, hummingbird hawk-moths may be able to establish a year-round population here as winters warm and allow the caterpillars to survive. The impacts of this are not fully understood. Generally, the importance of native caterpillars to our ecosystems is well understood but we are yet to fully understand the importance of adult moths. Therefore, it is difficult to fully assess the impacts these potential new residents may have. To ensure we have a better understanding of our current moth populations it is important to record common species too – something that can be easily overlooked. While it may be more exciting to photograph and record sightings of rare moths such as the hummingbird hawk-moth, it is just as important to record our everyday species too. If species that are common today start to decline, having data sets from when they were abundant and successful can help identify potential problems they’re facing and enable solutions to be found.

Long-term data sets like these are incredibly important to monitor how moth abundance changes over time. It is particularly useful for species like the hummingbird hawk-moth, which can have such dramatic annual variations in population size. Short-term increases such as the large influx we had this year can hide longer-term declines in populations. Despite the importance of long-term data sets, the NMRS itself is quite rare. Many other countries are seriously lacking long-term data sets, not just for moths but many other species, too. Unfortunately, science is not immune to politics. Short-term political cycles and the need for quick financial returns favours shorter-term studies, making investment into long-term data collection less desirable. However, citizen science schemes like the NMRS can help avoid these problems.

In times of financial pressure, citizen science can be a more affordable option for large-scale data collection. High volumes of engagement can enable vast data sets to be built up without the high costs associated with a team of specialists collecting data. There are still drawbacks: all records still need to be checked by specialists to ensure species identification is correct, the apps and websites used to collect data need to be built and developed, and sufficient awareness needs to be spread to ensure a representative data set can be acquired. There may be other potential hurdles to overcome such as a geographic bias in sampling, and insufficient data may be collected in areas with low population densities or in lower income areas where access to the technology may be a challenge. However, involving people directly with data collection can deepen their interest and appreciation of the natural world and foster a sense of responsibility for its protection. This bottom-up engagement and awareness helps to encourage longer-term participation in conservation efforts.

My chance encounter with the hummingbird hawk-moth this summer was a beautiful but stark reminder of how our climate and wildlife are changing. It also reminded me of how important citizen science schemes such as the NMRS are. So, the next time you spot a moth, take a closer look. You don’t need to be an expert to help out; simply taking a photograph, identifying the moth and submitting your record can help build the long-term data we need to protect our wildlife. By recording what we see, we can turn everyday encounters into valuable scientific data and ensure that future generations can enjoy these remarkable insects too.