Mesopsocus immunis, Talkin Tarn, 4 August 18 (1 of 2)
Female Mesopsocus immunis barkfly found on a fencepost at the edge of woodland to the north of Talkin Tarn, 4 August 18.
I'd given up trying to determine the species of female Mesopsocus barkflies earlier in the year after several failed attempts. In order to do this reliably, it's necessary to determine the shape of the apical lobe of the subgenital plate, which is pointed in the case of M. immunis, but rounded in the case of M. unipunctatus:
www.brc.ac.uk/schemes/barkfly/key/A1-B-C2-D20-E1.htm
www.brc.ac.uk/schemes/barkfly/key/A1-B-C2-D20-E2.htm
However, even after microscopic examination at 40x magnification, this always seemed to be ambiguous. Nevertheless, as this specimen was dead anyway (after an encounter with a spider - see earlier photo!) I thought I'd have one final crack at it, but this time by first clearing the body in 10% KOH solution thus allowing the use of transmitted light.
Although this revealed the interesting fact that the insect was gravid, the tip of the lobe was still not clearly visible. Although it's not something I've ever attempted before, I eventually managed to extract the plate in its entirety - without doubt my finest achievement to date in the field of amateur entomology! The plate can be seen in the Photo 1 insert, which confirms the species as Mesopsocus immunis.
Both photos were taken with the integral camera on my SX10D microscope, the main shot at 20x and the insert at 40x magnification. The insect was measured at 3.9mm in length, and the "wingspan" of the subgenital plate at slightly under 0.8mm.
Mesopsocus immunis, Talkin Tarn, 4 August 18 (1 of 2)
Female Mesopsocus immunis barkfly found on a fencepost at the edge of woodland to the north of Talkin Tarn, 4 August 18.
I'd given up trying to determine the species of female Mesopsocus barkflies earlier in the year after several failed attempts. In order to do this reliably, it's necessary to determine the shape of the apical lobe of the subgenital plate, which is pointed in the case of M. immunis, but rounded in the case of M. unipunctatus:
www.brc.ac.uk/schemes/barkfly/key/A1-B-C2-D20-E1.htm
www.brc.ac.uk/schemes/barkfly/key/A1-B-C2-D20-E2.htm
However, even after microscopic examination at 40x magnification, this always seemed to be ambiguous. Nevertheless, as this specimen was dead anyway (after an encounter with a spider - see earlier photo!) I thought I'd have one final crack at it, but this time by first clearing the body in 10% KOH solution thus allowing the use of transmitted light.
Although this revealed the interesting fact that the insect was gravid, the tip of the lobe was still not clearly visible. Although it's not something I've ever attempted before, I eventually managed to extract the plate in its entirety - without doubt my finest achievement to date in the field of amateur entomology! The plate can be seen in the Photo 1 insert, which confirms the species as Mesopsocus immunis.
Both photos were taken with the integral camera on my SX10D microscope, the main shot at 20x and the insert at 40x magnification. The insect was measured at 3.9mm in length, and the "wingspan" of the subgenital plate at slightly under 0.8mm.