I love flies.
Okay, no one, including me, likes the buzz of house flies around their food or the indescribable panic as one vibrates into a facial orifice. But flies as an insect order are as fascinating as they are diverse. As a whole, they serve an incredibly important role in the wheel of life on earth. They are the composters, decayers, decomposers. The ones who clean up the waste of death, trigger decay and begin the recycling of earth’s nutrients. So even if you don’t like them, we can perhaps respect their place in the ecosystem, beyond driving all mammals to swatting distraction.
Today, I want to bring a mysterious fly into your awareness. This particular fly is interesting and striking, despite the paucity of information we have about its life history. It is called the snail blowfly or yellow-headed snail parasitic blowfly (Amenia imperialis), the latter, long-winded name describing both its bright yellow head and its reproductive predilections.
As is the case for many insects, the feeding habits of the immature stages are the most nefarious. The larvae of these flies are predatory parasites that feed on land snails, such as the ones in your garden, while the adults feed on flower nectar and presumably play a role in pollination.
These flies really are your ally, their children taking out would-be garden-decimators before they can slime their way through the strawberry patch, while the grown-ups pollinate the flowers that produce the berries to begin with. Since we know so little about these flies, we can only presume they have some power in suppressing or diminishing snail populations.
I see the adult flies regularly around my garden in Wollongong, usually buzzing around native flowers. The first time I noticed them nearly a decade ago I was shocked by their beautiful colours: the brilliant yellow head, combined with a shiny blue-green body flanked by big white spots. They are large and occasionally confused with bees since they’re always hanging out around flowers. As a side note, the failsafe way to tell the difference between a fly and a bee or wasp is to count the wings. Bees and wasps have two pairs of wings. Flies have only one pair. Their rear set has been evolutionarily reduced into two cute little nubs called 'halteres', which can’t easily be seen without a microscope.
Snail blowflies are exactly that: blowflies. The proper name for the blowfly family is Calliphoridae, which originates from Greek, meaning 'beautiful appearance', which, evidently, I don’t argue with. Insect taxonomists may have a different barometer of beauty, but the variety of lustrous colours displayed by many blowflies means the insect beauty pageant tips in their favour. I have no doubt our reticence to acknowledge their attractiveness is caused by our inability to forgive their penchant for rotten carcasses and poop.
The term blowfly comes from the old English terminology meaning a piece of meat that has been infested by maggots, as in 'flyblown'. Another fun fact: the first mention of the word 'blow' in reference to flies exists in the Shakespeare play Love’s Labour’s Lost. An apt metaphor for the apparent laboriousness of loving blowflies.
Taxonomically, the snail blowfly genus Amenia is somewhat confusing. Although it resides within Calliphoridae, the genus was initially thought to belong within Tachinidae, a family of flies known for their parasitism. But the genus also holds taxonomic affinity to Sarcophagidae, a family of flies known commonly as flesh flies for the members within whose larvae feed on living flesh.
The other fascinating peculiarity of these flies is the way they ‘give birth’. That is to say that, unlike most flies, they do not lay eggs, but instead produce very large, developed maggots, making them macrolarviparous. 'Macro' from the ancient Greek word makros meaning long or large, 'larvi' denoting larvae (as opposed to 'ovi' denoting egg) and 'parous' from the Latin root pariō meaning to produce or give birth. The ovaries of these flies release an egg into a muscular uterus within the female, where it hatches and moults into a large larva ready for birth and snail feasting. Honestly, the similarities between our species are astonishing.
Whenever I come across an insect like this, one that is beautiful and has a fascinating life history and yet is bound by mystery and a paucity of research, it makes me lament the modern machine of academia that requires a relentless pace of publication in fields that are deemed worthy by financial implication.
I believe that it’s vital we remember the significance and beauty of every creature in and of itself. We must preserve the things that nudge us to remember that we are woven into the fabric of the earth, not walking above it.
The snail blowfly reminds us that flies as a whole are more than a nuisance – they are an ever present and sometimes beautiful reminder of our mortality. Like tiny conduits of the earth’s nutrients, they remind us of the brutal equality among all living things. Because within the portal of death, it is through them that our bodies will return to the earth. That humbling fact makes me respect them. Their incredible diversity, life history and surprising beauty is what makes me love them.
