Specimen Showcase｜🦟 Small but Bitey
- Hong Kong Biodiversity Museum
- Mar 10
- 3 min read
There are over 6000 species of biting midge, small flies in the family Ceratopogonidae (Newman, 1834) - more than all mammal species - distributed all over the world except for the poles. Despite the family nickname, not all biting midges bite. Many live off fungi or aquatic algae; some off plants, and are important pollinators of crops like the cocoa bean. For those species that do bite, as with mosquitoes, it is the females that do all the biting, more specifically they suck the blood of animals when they need extra nutrients for the eggs they’re growing to properly mature. Different biting midge taxa feed on different prey, ranging all the way from mammals, turtles, lizards, even fish, to invertebrates like themselves, from which they suck haemolymph, which is the invertebrate equivalent of blood: from millipedes, butterflies, dragonflies… Some species even inject enzymes into small invertebrate prey which liquefy their insides, which they then drink like a grim smoothie. Even in biting species, both males and females will feed on other food such as nectar, with some contributing to pollination. In Hong Kong, three genera feed on mammals (which unfortunately includes human) blood, one of which is 𝘊𝘶𝘭𝘪𝘤𝘰𝘪𝘥𝘦𝘴: the focus of today’s post.
Biting midges are 1 to 3 mm in length, which is so small it’s hard to even imagine. Picture if you can the length that your fingernails grow in about 2 weeks - the size of the bit that sticks out past your fingertip, that you need to clip off. (Depending on how fast your fingernails grow) that’s roughly as big as biting midges get. It perhaps comes as no big surprise that another common name for these lil’ creatures is “no-see-ums” (because you can’t see them). They’re also called “punkies” (also referencing their small size) and “sandflies”, because they prefer sandy, marshy or coastal areas full of moisture, where they lay their eggs in damp and rotting places. 𝘊𝘶𝘭𝘪𝘤𝘰𝘪𝘥𝘦𝘴 females tend to travel around in swarms and are more likely to bite you at dusk or dawn when they are most active, and more in summer.
Despite being so tiny, 𝘊𝘶𝘭𝘪𝘤𝘰𝘪𝘥𝘦𝘴 midges can cause havoc when they bite animals, as they are vectors for several diseases. They can transmit parasitic worms and viruses, which affect mostly livestock such as sheep and cows. The science behind how vectors (generally arthropod species) carry these infectious agents without becoming ill themselves is really interesting and complicated. Briefly, the specially evolved innate immune system of midges curbs excessive virus proliferation and prevents pathological reactions, and viruses have evolved to behave differently in midge cells versus mammalian cells they infect (they reproduce and exit midge cells gently whereas they burst mammalian cells open on exit, which causes the disease). Although their bites can be painful and very itchy, biting midges are relatively safe when it comes to humans, as no diseases are transferred by them to us: the worst thing that can happen is an allergic reaction. Still, you might want to wear long, skin-covering clothing or apply insect spray if you’re visiting a risk area, to avoid the itchy annoyance (or move to the South Pole if you’re all out of Deet). If you do get bitten, like it happened to one of us just a few days ago, try your best to refrain from scratching, and within an hour or so for most people, the effect should disappear.
If you really squint and focus hard you can just about make out our teeny 𝘊𝘶𝘭𝘪𝘤𝘰𝘪𝘥𝘦𝘴 specimen at the Hong Kong Biodiversity Museum. It might be a lot easier to look at these high magnification photos. We’re not sure what sex the larva is or what its life story will be, so we can’t tell if it was just a helpful pollinator with a sweet tooth for nectar, or that, plus a ruthless blood-sucking mum!
Text：Elvira Rey Redondo
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