Batman (Myathropa florea)
Wing Length 7-12mm.
Body Length 10-14 mm
Flight. Apr-NovDiscover the hoverfly with a superhero emblem, buoyant larvae that dive like miniature whales, and a surprisingly strong association with cemeteries.
This is a very distinctive hoverfly which carries around a super-hero insignia proudly on its thorax. It’s a common hoverfly spotted from the start of spring to the end of autumn. Often a visitor to flower gardens for nectar and pollen but more commonly found on woodland sunlit glades/rides hovering at head height or alongside watercourses, woodland edges and it’s, eerily, often spotted in cemeteries.
Welcome to this month’s hoverfly species deep dive.
In my local area, the ice cream van often patrols the streets accompanied by the unmistakable theme tune from the 1960s Batman television series, no doubt enjoying record sales after the heatwaves of the summer.
Na, na, na, na, na, na, na,na,na,na,na na,na,na,na,na Batmaaaaaan!.
If that tune is now lodged firmly in your head for the rest of the day, I can only apologise.
For those unfamiliar with the series, I'm referring to the wonderfully camp live-action version starring Adam West rather than any of the modern-day adaptations. It's great fun and well worth a watch. Whenever I hear that famous theme, my mind immediately drifts to this hoverfly, and I invariably find myself asking, "Where's Robin?"
How to identify Batman in the field
The Batman Hoverfly's claim to fame is, of course, the dark marking on the thorax that bears a striking resemblance to the famous bat symbol.
Beyond this, the species has a boldly patterned abdomen with yellow and black markings that gives it a distinctly wasp-like appearance. These markings are highly variable and can change according to the conditions experienced during development. Individuals emerging in cooler periods of the year often appear duller and darker, while those emerging during the warmth of midsummer frequently display bright lemon-yellow markings.
This temperature-driven variation is known as seasonal polymorphism, resulting from environmental conditions during the larval and pupal stages. So, the famous "Batman logo" is not always obvious, and the abdominal markings can vary considerably. As a result, the species is sometimes confused with the droneflies (Eristalis spp.), particularly as both possess the characteristic loop in the wing vein (R4+5).
A closer look at the wing venation provides a more definite identification. In Myathropa florea, veins R1 and R2+3 reach the wing margin separately. In droneflies, these veins converge and join near the wing edge. If you have the opportunity to examine one closely, this feature can help make that identification certain but in the field it might not be so obvious, even with a hand lens.
Lifecycle of Batman
I mentioned above that Batman hoverflies are strongly associated with cemeteries. Contrary to what you might expect, this has nothing to do with bats, graveyards or the dark knight himself. The connection is much simpler and comes down to two basic requirements: food and suitable places to raise the next generation.
Males are highly territorial and often announce their presence with an audible, high-pitched buzzing that can sound surprisingly angry for such a small insect. They spend much of their time patrolling sunlit woodland rides and glades, flying in repeated circular routes while defending favoured territories against rivals. To fuel this energetic lifestyle, males rely heavily on carbohydrate-rich nectar.
Females also require nectar for energy, but they have an additional nutritional demand. To produce eggs, they need protein-rich pollen, which stimulates egg development, a process known as oogenesis.
Because adults are active for much of the year, they have to take advantage of different flowering plants as the seasons progress.
Spring• Blackthorn (Prunus spinosa)
• Hawthorn (Crataegus monogyna)
• Cherry blossom
Summer
• White umbellifers (family Apiaceae)
• Bramble (Rubus fruticosus)
• Meadowsweet (Filipendula ulmaria)
• Sweet Chestnut (Castanea sativa)
• Goldenrod (Solidago spp.)
Autumn
• Ivy (Hedera helix)
When the time comes to lay eggs, females seek out a very different habitat. Veteran and ancient trees are especially important because they often contain water-filled cavities known as rot holes. These pockets of decaying wood provide the perfect nursery for Batman Hoverfly larvae.
Their larvae are saprophagous detritivores, which means they feed on decomposing organic matter and the dense communities of bacteria and microorganisms living within it. Rot holes are essentially nutrient-rich woodland soup, and the larvae thrive within them.
Flowering shrubs, wild plants, and particularly old trees are often abundant in churchyards and cemeteries especially those that have been allowed to remain a little untamed. As my beloved and I share a fondness for visiting churches, we frequently find ourselves exploring the grounds with less manicured areas. These forgotten corners can be havens for wildlife, and there is always the exciting possibility of encountering some hoverflies amongst the vegetation.
Recent research has shown that larvae can develop more rapidly and emerge as larger adults with longer wings when rot holes contain the faeces of Cetoniine beetles. These include familiar flower chafers such as the Rose Chafer (Cetonia aurata) and the Garden Chafer (Phyllopertha horticola).
These beetles as larvae act as ecosystem engineers. By chewing through decaying wood, they create fine woody debris and nutrient-rich frass that encourages microbial growth. In turn, this creates an even richer feeding environment for hoverfly larvae.
The larvae themselves are commonly known as rat-tailed maggots, although I prefer the term long-tailed maggots. Whatever you choose to call them, they possess one of the longest breathing tubes in the hoverfly world.
This remarkable tail is actually an extensible respiratory siphon. The larvae remain suspended deep within their decaying liquid habitat while the siphon reaches the surface like a snorkel. Having such an extraordinarily long breathing tube allows them to exploit parts of the rot hole that are inaccessible to many other organisms, where oxygen levels are extremely low.
 |
| Batman larva |
Unfortunately, I don't have any veteran or ancient trees in my garden so instead, I create hoverfly lagoons. Using everyday household containers filled with decaying organic matter, it is possible to mimic the conditions found in natural rot holes and create miniature nurseries for saproxylic hoverflies.
An idea originally developed by Ellie Rotheray associate professor at the University of Sussex and daughter of the Graham E. Rotheray who along with Francis Giilbert wrote the book ‘The Natural History of Hoverflies’ - a wonderful book about all aspects of hoverfly biology published in 2011.
Hoverfly lagoons are a fantastic addition to any wildlife gardens and if you're anything like me, irresistible not to inspect every few days in the hope of finding larvae.
These artificial lagoons have also generated some fascinating citizen science observations. People have discovered that when the larvae are disturbed, or sense danger near the surface, they can rapidly expel air from their respiratory system and lose buoyancy almost instantly. This allows them to sink quickly away from potential threats.
This behaviour is remarkably similar to that of diving marine mammals such as whales, which regulate buoyancy by controlling the amount of air within their lungs.
Predators certainly take advantage of this abundant food source. Foxes, for example, have been found with stomachs packed full of hoverfly larvae after drinking from water-filled cavities and other locations where the larvae occur. As noted in The Natural History of Hoverflies (p.13), these nutrient-rich larvae can clearly form an important food resource for opportunistic mammals.
Geographical range:
The Batman hoverfly is widespread, with a range stretching from the west coast of Ireland all the way to the Pacific coast of Russia. It occurs throughout most of Europe, extending north into Scandinavia and south into North Africa.
Not content with that, it has also managed to establish itself on the Pacific coast of North America, where it was first recorded in 2005 and continues to spread. Fortunately, it appears to be a harmless newcomer and is therefore described as adventive rather than invasive.
• Adventive means not native to an area and not yet fully established or permanently naturalised - arriving by wind, animals, or human transport but only temporarily or locally surviving without becoming self-sustaining.
As for how it got there, nobody knows for certain. My money would be on an accidental lift in cargo, imported plants or soil, although that's only speculation. Hoverflies aren't exactly known for booking transatlantic flights.
If you live in the USA and think you've spotted one, please let me know. I'd be interested to hear where and when you found your own miniature Dark Knight.
There are only two other species worldwide that belong to this genus Myathropa - M.Semenovi recently discovered in the Kashmir Himalayas 2024 and M.usta known only to the island of Madeira.
If you live or visited those regions let me know, especially if you have spotted either hoverfly or have photographs of either.
Next time, I hope to delve in the tenuous folklore and classification of Batman hoverfly and explain why in some quarters this hoverfly is still often referred to by the common name Death’s Head hoverfly.
Next steps:
If you enjoyed this article and would like to discover more hoverfly species, visit Hoverfly Species
Alternatively, explore one of the six habitats where hoverflies are commonly found and discover which species you may have spotted during your own wildlife adventures:
Whether you're searching in your garden, exploring woodland trails, or visiting wetlands and upland areas, there's always a chance of discovering a fascinating new hoverfly species.
Alternatively enter your email address at the side an never miss an email of any future posts.
I also write on Substack check me out here ---> Easily Distracted by Hoverflies Substack
Sources
S.Ball and R.Morris British Wildlife Vol 33 Num 6 May 2022: Understanding Eristalis hoverflies: a guide to identification.
Rotheray G.E & Gilbert F.S 2011 The Natural History of Hoverflies. Forest Text
https://archive.org/details/naturalhistoryof0000roth
Sánchez-Galván, I.R., Quinto, J., Micó, E., Galante, E. & Marcos-García, M.A. (2014). Facilitation Among Saproxylic Insects Inhabiting Tree Hollows in a Mediterranean Forest: The Case of Cetonids (Coleoptera: Cetoniidae) and Syrphids (Diptera: Syrphidae). Environmental Entomology, 43(2): 336-343. DOI: 10.1603/EN13075.
https://genius.com/Neal-hefti-batman-theme-lyrics
No comments:
Post a Comment