His Dark Materials
His Dark Materials

A spy-fly was a mechnical insect designed to spy on someone and then return with information. They had clockwork mechanisms worked by evil spirits. The spy-fly would not stop as long as the spirit is inside, and upon release, the spirit would kill the first person it could.[1]


A spy-fly trapped in a jar.

Spy-flies could be found in Morocco. John Faa once saw one there.[1]

Marisa Coulter sent two spy-flies to locate Lyra Belacqua after she ran away from her home.[1] Farder Coram managed to capture one and Lyra kept it in a box, later using it to trick Mrs Coulter.

A smaller spy-fly

Later, Captain Hartland from the Consistorial Court of Discipline left a spy-fly in the Botanic Garden to spy on Malcolm Polstead's conversation with Lucy Arnold and Charles Capes in the Linnaeus Room however Malcolm managed to capture and kill it before throwing it out of the window.[2]

The CCD managed to breed the flies smaller with even better memories to the point where it could repeat conversations exactly.[2]


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HDM Wiki has 6 images of spy-flies.


  1. 1.0 1.1 1.2 Northern Lights, Chapter 9
  2. 2.0 2.1 The Secret Commonwealth, Chapter 10