Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Caltha

1a > Leaf-miner: Mine linear but becoming very broad, up to 5mm, greenish, normally on lower leaves, near water (Spencer, 1972b: 91 (fig. 313), 94).

After a short lower-surface beginning follows a quickly widening, upper-surface corridor that is strongly contorted, and runs from the leaf base towards the margin to widen there into a blotch. Corridor sides very irregular. Primary feeding lines well visible. Frass in pearl chains. Before pupation the larva leaves the mine through a large semicircular exit slit; however, the black puparium mostly remains stuck under the exit flap. Exit slit in lower epidermis (Pakalniskis, 2004a).

On Caltha palustris in Britain and elsewhere. Uncommon - recorded in Wilts and Inner Hebrides in Britain and continental Europe.

Phytomyza calthivora Hendel, 1934 [Diptera: Agromyzidae].

1b > Leaf-miner: Larva forming a long, narrow, upper surface mine. Pupation external (Spencer, 1972b: 91 (fig. 313); Spencer, 1976: 394 (fig. 694), 395).

Long upper-surface, parallel-sided corridor, pale green, later browned. The corridor is little contorted and hardly branching. Frass in gradually coarser grains. Pupation outside the mine; exit slit in lower epidermis (Hering, 1957) or upper epidermis (Pakalniskis, 2004a).

On Caltha palustris in Britain and elsewhere. Widespread but local in Britain. Also recorded in continental Europe.

Phytomyza calthophila Hering, 1931 [Diptera: Agromyzidae].

1c > Leaf-miner: In the first instar the larva mines the leaves, forming short, irregular, blotch-like mines, but in later instars it lives externally, feeding in spun leaves and often twisting those of tender shoots. Larval head light-brown or yellowish brown, edged with black postero-laterally, ocellar area blackish; prothoracic plate black edged with whitish anteriorly; abdomen dull dark green; pinacula distinct, black, sometimes brownish but with black bases to setae; anal plate large, black (Bradley et al., 1973). Small, full depth mine without a definite shape; little frass. Some silk is deposited in the mine. The larva soon leaves the mine and continues feeding among spun leaves.

Polyphagous. On numerous genera and species in several plant families, but not yet on Caltha, in Britain. Widespread in Britain and continental Europe. Also recorded from the Channel Is.