Country diary: if they're not tadpoles what are these little wrigglers?

Stamford, Lincolnshire: These curious creatures won't grow into cute froglets, they'll be menacing little blood suckers

In a week, heat, then rain. Heavy air settles, and thunder seems hiding around its edges. Water collects in everything concave. Then my five-year-old daughter comes in and tells us there are tadpoles outside.

It's late for tadpoles. I've seen no frogspawn, but she's insistent. And there, in an outdoor sink, amid leaf rot, detritus and two inches of stagnant rain, is that familiarly sinuous movement: front heavy, tail frantic. Only not quite.