Pyrophilic smoke flies (Diptera: Platypezidae: Microsaniinae) from prescribed burnings in boreal Finland: occurrence and behaviour of adult flies and first observations of immature stages

Smoke flies, belonging to the Diptera family Platypezidae and the Microsania genus, are highly specialized insects with a remarkable response to smoke. Although their attraction to smoke has been recognized for over a century globally, their immature stages and breeding habitat have remained unknown. To address this gap, researchers in boreal Finland conducted prescribed forest burns between 2022 and 2024, collecting smoke fly specimens and soil samples.

The flies were observed swarming and reproducing at all seven burn sites. Of the six Finnish species, Microsania pallipes was the most prevalent (94%). Following these observations, soil samples were analyzed, revealing larval stages identified by mtDNA COI barcodes. This discovery is the first to document the larval habitat in burnt soil, resolving a long-standing knowledge gap regarding smoke fly breeding sites.

The examination of the immature stages' morphological characteristics will contribute to elucidating the phylogenetic placement of the Microsaniinae within the Platypezoidea lineage.