Bastard Toadflax bug at Hartslock

Spent a lovely afternoon pottering around Hartslock today with a friend … the showers held off for for most of the time and, with all the summer flowers in full bloom, the site looked really spectacular.

One of my favourite species-complexes centers on Bastard Toadflax (Thesium humifusum), a rare perennial of short-turfed chalk downland. The plant itself is quite small but its ‘politically correct’ common name of ‘Stars in the Grass’ aptly describes the dainty little white, star-shaped flowers and the way that the creeping branches climb through short grass and herbage. This plant is exciting enough for keen botanists to travel from miles around but rarer still is the little bug (Sehirus impressus) that lives by sucking the sap of only this rare plant. They are a dark gun-metal blue colour and similar to the commoner Pied Shieldbug. Today we saw an adult and many juvenile bugs – characterised by their red & black abdomens – see the photos.

Ever rarer still though is the mildew that only grows on Bastard Toadflax – Erisiphe thesii – this has only been recorded from Hartslock and forms a downy mildew on the tips of Bastard Toadflax stems. If you see Bastard Toadflax and it has a grey mildew then you are looking at Erisiphe thesii 🙂