(2 images) Herring Gull 2cy (argentatus), July 14 2003, Tampere, Finland (61.31N, 23.43E).

A 2cy argentatus, showing vermiculated patterns on second generation wing-coverts. In many respects an average moult score for mid-July at Tampere. The complete moult is halfway with most wing-coverts and the inner primaries moulted to second generation. Primary P8 has been dropped and P9-P10 are still juvenile. P1-P6 are fully grown second generation flight-feathers; P6 just exceeds P5 in the folded wing. Now the central greater coverts are dropped, the juvenile secondaries underneath are exposed.
Many tertials and wing-coverts are replaced for second generation feathers. The upper tertials have been replaced and the lower tertials are still juvenile. The gap in the central greater coverts is almost closed; the new greater coverts grown in descendant order, from the outer-wing inwards, as is the common sequence and the gap is closed at about greater covert #6-8. Juvenile wing-coverts are still present in the upper row of lesser coverts. The fresh upper scapulars, which are probably third generation, look very second generation like.

By July, the warm brown tones of the first moulted second generation feathers (inner greater coverts and inner median coverts) are faded to plain white, leaving a contrasting barred pattern on the wing-coverts. On average, 2cy argentatus is more contrastingly patterned than same aged 2cy argenteus, especially regarding the pattern on the central greater coverts. However, some argentatus are distinct "washed out" brown, showing the common vermiculated pattern of 2cy argenteus. 
The last moulted coverts are the central greater coverts and outer lesser coverts, replaced by mid-August. From mid-August onwards, 2cy argentatus start the partial autumn moult, starting again to drop the upper tertial and inner greater and median coverts. 

In the tables below, the primary moult scores of 2cy July argentatus in Finland can be read: