Birka annulitarsis (Thomson, 1870)

Macek, Jan, 2013, Descriptions of larvae of Birka annulitarsis and B. cinereipes (Hymenoptera: Symphyta: Tenthredinidae), Acta Entomologica Musei Nationalis Pragae 53 (2), pp. 815-819 : 816-818

Birka annulitarsis (Thomson, 1870)

( Fig. 1 )

Material examined. CZECH REPUBLIC: MORAVIA MER.: Bílé Karpaty PLA, Machová (7171), 30.viii.2007, 4 larvae on Pulmonaria angustifolia ; U Petrůvky NM (6872), 25.ix.2008, 7 larvae on Pulmonaria angustifolia , 1 female emerged 12.v.2009, all J. Macek lgt. ( NMPC) .

Description of the last feeding instar larva. Body length 10–12 mm. Head black, in lower part yellowish; whole head covered with scattered fine homogeneous pubescence; clypeus with six setae, labrum with four setae; mandibles with two setae, stipes and palpifer with two setae; second segment of maxillary palps with one small seta; praementum with two setae, second segment of labial palp with one short seta; body in upper part grey-yellowish, in lower part paler; cuticle granulose, spiracles black; first annulus of prothorax with a pair of large dorsal lobes with short cylindrical setae, third annulus of prothorax and first and third annulus of mesothorax with a pair of short wart-like projections with several short cylindrical setae; trochanter as long as femur, with scattered long hair-like setae, tibia as long as tarsus with three hair-like setae, third abdominal segment with seven annulets; second and fourth annulets with a pair of short dorsal cylindrical setae, first postspiracular lobe with one, second postspiracular lobe with two short cylindrical setae, prominent subspiracular and suprapedal lobes with short cylindrical setae, ninth abdominal segment with transverse, bilobed ridge with short scattered cylindrical setae, suranal lobe with short hair-like setae posteriorly; basal interior parts of prolegs with several long hair-like setae.

Notes on identification. The larvae of Birka annulitarsis differ from the similar larvae of B. cinereipes in smooth abdominal segments and bilobed transverse ridge on the ninth abdominal segment.

Bionomics. Habitat: mesic meadows, oak-hornbeam and thermophilous oak forests from colline to submontane zone. Polyvoltine. Flight period from mid April to the beginning of September.

Larvae were collected in August and September on leaves of Pulmonaria angustifolia in the flowery meadows of Bílé Karpaty Protected Landscape Area in southern Moravia, Czech Republic. They can be found by day, tightly attached with body outstretched on the base of upper surface of leaf blade of the food plant. The larvae are easily detected because of the sceletonized holes on the leaves. Mature larvae build a firm cocoon in soil, where they hibernate in praepupal stage.

Discussion. ZIRNGIEBL (1954) noted Rubus sp. as host plant without any more details on the developmental stages relating to this plant. For that reason LISTON (1995) and TAEGER et al. (1998) mentioned Rubus as a problematic food plant and indicated it with a question mark. MACEK (2009) first recorded Pulmonaria sp. from Bílé Karpaty Mts. as a proved larval foodplant based on the collection and rearing of larvae. The food plant is here specified as Pulmonaria angustifolia L. Besides , adults of this species were also swept in various parts of Bohemia in deciduous forests with rich growth of Pulmonaria officinalis , which might be another larval foodplant.

Figures

Figs 1–2. 1 – Birka annulitarsis (Thomson, 1870), 2 – Birka cinereipes (Klug, 1816): a, d, e – mounted larva from alcohol; b, c – living larva; a, c – lateral view; b – dorsal view; d – frontal view; e – abdominal segment IX, dorsal view. Scale: a – 5 mm; b, c – 10 mm; d, e – 1 mm.