Sightings of the Drab Wood-soldierfly - Solva marginata (Meigen, 1820) at Stonham, Suffolk in July 2024
The attractive Xylomyid, the Drab Wood-soldierfly - Solva marginata (Meigen, 1820), is reasonably widespread over the southern parts of the UK. Although previously thought of as uncommon, it may actually be slightly more frequent than that but is generally seldom numerous where it does occur.
Just after mid-July 2024, I was contacted by Graham Denny who farms at Stonham in central Suffolk with some pictures of a distinctive-looking fly he had taken on his phone. Graham is an award- winning conservation-minded farmer who has spent 40 years nurturing the habitat necessary for Turtle Doves and other farmland birds to thrive as well as bees, butterflies and all sorts of other insects on his land. Graham has a particularly good eye for noticing wildlife of all sorts and his pictures clearly showed he had a specimen of S. marginata which was of interest straight away. There are eleven post-1882 records for S. marginata in Suffolk (Vincent, 2021). These include several records from the eminent Claude Morley in the first half of the 20th century and then only a couple in the subsequent decades. There are slightly more records into the 21st century including a pair of dead specimens collected for me from a conservatory in Ipswich by Evie Swanton in 2019. The last entry on iRecord is from 2020 by Gary Lowe in Boyton near Woodbridge. Therefore, Graham’s subsequent communication a few days later that there were now six specimens dancing around on a sunny bit of hedge prompted me, at Graham’s invitation, to go and have a look myself on July 20. Sure enough, when we walked along the sunny side of the said
Solva marginata from Stonham, Suffolk, 20-08-2024.
One of the ‘dancers’ was eventually collected (they can move very quickly) to make 100% sure of the determination and was confirmed under the microscope as a maleS. marginata using the key in British Soldierflies by Alan Stubbs and Martin Drake (Stubbs & Drake, 2014).
The next day, 21 July, one of Graham’s colleagues, Allan (Rab) King, who is a keen photographer went over to Stonham to take some pictures of the flies and other creatures and between them they estimated numbers of Solva marginata to be around 40–50 individuals along approximately 100m of hedge. This then appears to be a significant population within what is currently known of the Suffolk distribution of this fly and may be a significant number nationally. Numbers slowly declined after this with Graham counting around 20 on the 26 July but none then seen after this into August.
The habitat requirements of S. marginata are described by Falk, 2024 as ‘that (it) occurs in association with old and recently fallen trees and also log piles. It clearly favours willows and poplars at many sites and can occur in association with scattered riverside trees as well as woodland and thickets, especially those associated with wetlands. Larvae develop in the rotting cambium layer beneath the bark of trunks, stumps or logs that have been dead for less than 2 years, and it may be able to exploit rot in old living trees too. The larvae are saprophagous.’
s farm where a large riverside hedge of mixed species, with plentiful Willow and Poplar, is regularly thinned out and the logs then left in situ to rot down. The river is oriented southwest at this point on the farm meaning there are east facing sides to the hedge which is where most of the conspicuous fly activity was observed. The fly seems to have found an ideal bit of s farm in Stonham
As an interesting final aside this whole small sequence of events illustrates rather well what can be achieved through an engaged and interested landowner with an eye
Many thanks to Graham Denny for recording the species in the first place and then inviting me to have a look and to Rab King and Jeremy Early for their photographs. Thanks also to Peter Vincent for editing this piece.
References
Falk, S. (2024). Flickr album of Solva marginata – Drab Wood-soldierfly [online]. https://www.flickr.com/photos/63075200@N07/albums/72157631392015938/ [Accessed 07-08-2024]
iRecord details of Solva marginata [online]. https://irecord.org.uk/all-records [Accessed 07-08-2024]
Stubbs, A. E., Drake, M. (2014). British Soldierflies and their allies. 2nd Ed. British Entomological and Natural History Society. 183. Vincent, P. (2021). The Diptera of Suffolk. Part Four: Xylophagidae, Athericidae, Rhagionidae, Tabanidae, Xylomyidae, Stratiomyidae, Acroceridae, Bombyliidae, Therevidae, Scenopinidae, Asilidae. Trans. Suffolk Nat. Soc., 57: 23-34.
David Basham, Graham Denny, Allan King, and Peter Vincent