Blasticotoma filiceti larva foam ball on Lady Fern Athyrium filix-femina © Guy KnightLlanelli Naturalists Newsletter - November 2005 - No 72
Adrian Fowles

There are few UK localities for the RDB3 sawfly Blasticotoma filiceti, and the only Welsh record is of a single adult from Cors Graianog SSSI near Garndolbenmaen in Caernarvon-shire, found by Roger Key in June 1997. The larvae tunnel into the stems of ferns and produce characteristic white foam balls as large as walnuts on the outside of the stems. During a 4-hour search at Cors Graianog in August by Mike Howe and Guy Knight, 14 foam balls were found on the stems of 8 plants of Lady Fern Athyrium filix-femina, most of which were low down towards the base of the stems. We would be grateful to receive any records of this distinctive sawfly if you are lucky enough to find it.

Reproduced from I-NET UPDATE, 9: Sept 2005.  I-NET is CCW’s internal working group for invertebrate issues.