Tytthaspis sedecimpunctata (Linnaeus, 1758)
A common species across southeastern England north to the Wash but with scattered, mostly coastal, records from Wales and the West country. Far less frequent in the midlands and the north although there are several modern coastal records from the northern Scottish highlands. The adults are powdery mildew feeders and, typically, insects of open grassland and moorland. Adults are common in grass tussocks, moss and leaf litter throughout the winter, becoming active during mild spells; during the very mild season of 2006/7 they were swept from long grass on Croxley moor or around Radlett road during every month from october to february. They are noted for overwintering in large groups, the largest UK coccinellid aggregation ever recorded was of Tytthaspis with over ten thousand individuals. During march they are active in large numbers, often colonising areas of flowering Ranunculus acris or R.ficaria, with several adults in each flower and colonies consisting of hundreds of beetles. During this time they may be found everywhere by sweeping low herbage and long grass. Throughout Watford, at least during 2006 and 2007, they have been by far the most common spring coccinellid. Numbers seem to fall in the summer months and increase in the autumn when again they are to be found everywhere, including the town centre and, with the possible exception of woodland where numbers are generally very low, in all habitats. Throughout september and october 2006 they were extremely abundant on Oak and Ash across Cassiobury park.

2.5-3.3mm. Glabrous and short oval, almost round. Ground colour yellow to very pale cream, appendages darkened towards apices. Head entirely yellow or with varying amounts of black, commonly darkened longitudinally between eyes. Antennae a little longer than distance between eyes. Pronotum broadest at base, finely bordered laterally and strongly sinuate basally, with six well defined black marks and sometimes the anterior margin narrowly black. A fully melanic form, f.poweri, is uncommon (Majerus). Scutellum not visible. Each elytron with 8 (rarely 7 or 9) dark marks which may be to some extent fused, the lateral ones commonly so, and a dark stripe bordering the suture. Head and pronotum finely punctate, elytra more coarsely so.
Unlikely to be confused with any other species.

Description from 4 Watford specimens at X20