INTERVIEW
The larval stage is the most important when it comes to ecology. That’s when these organisms do 90% of their feeding, the decomposition
Above (left to right): Mosquito larva and pupa
Top right: Orthonevra nitida is a species of syrphid fly in the family Syrphidae specimen was from 1850 and like this (she does a good impression of a squashed fly), and when I found the type specimen, the locality said ‘VOLCANO, JAVA’. So I spent three weeks looking for this mosquito on the side of a volcano in Java.
“Eventually, molecular analysis found the one species was actually four – that’s why some were transmitting the disease and not others.”
A few times during our conversation, I assume McAlister is talking about a fly’s adult stage, and she reminds me of how most people, even biologists, tend to overlook the larval stage of flies.
“The larval stage is the most important when it comes to ecology. That’s when these organisms do 90% of their feeding, the decomposition. The adults are just the ones we notice because they fly around…” She trails off to show me some botfly larvae with interesting anal spiracles.
“People are always trying to kill rat-tailed maggots, but they are really important decomposers and the adults (drone flies) are in the top six most important pollinators in the UK.”
By one extremely speculative estimate, included in The Secret Life of Flies, there are 17 million flies for every person on Earth. McAlister is unsure about these numbers, but believes the public underestimates how many flies there are, and their diversity, because so many Diptera mimic other species. “People will look at that one and think ‘wasp’, and that one and think ‘bee’.” She even shows me flies that look like spiders, including the incredibly rare Mormotomyia hirsuta, dubbed the ‘terrible hairy fly’.
Conservative estimates predict that there are over one million species of Diptera across the order’s 170 families. However, McAlister says dipterists have been “freaked out” by a recent Canadian paper that suggests that the true figure could be far, far higher.
“It found Diptera has been completely underestimated. It was the gall midges particularly – the authors extrapolated data from international collections and said there could be 1.8 million species just in that family.”
McAlister seems able to hone in on the specimen she wants to show me partly from memory, despite
16 / The Biologist / Vol 66 No 2