Machimus Robberfly (Machimus sp.)

Our species of the month is one of the Machimus Robberflies (Machimus sp.). This moderately-sized fly is an ambush predator that feeds on other insects by catching them and injecting them with neurotoxins to paralyse their prey while proteolytic enzymes digest them to create a drinkable meal. It sounds gruesome but it's a very effective way of catching a meal - globally there are over 7000 species of robberfly and all are predatory in this way. Practically any insect can become prey for a robberfly, and they aren't put off by the size of their meal, often going for insects over twice their size, nor whether it has a sting or chemical defences that put off most other predators.  

Robberflies play an important role in ecosystems by helping to control populations of their prey species, which can include species that are pests for humans. They do this in every continent on earth except Antarctica.

The first Alderney record for this genus came from a young citizen scientist during the Alderney Wildlife Trust Bioblitz in 2025. It was initially identified by the Alderney Wildlife Trust as a Kite-tailed Robberfly (Machimus atricapillus), but a subsequent review from the UK Soldierflies and Allies Recording Scheme indicated this female has too many white bristles to be a Kite-tailed Robberfly, and is instead one of the other Machimus species.