Butterworts or Pinguicula have a fleshy leaf covered in a sticky, greasy secretion, that catches tiny flies. The plants has an attractive rosette of these leaves but also has lovely flowers making it an excellent houseplant for a north facing windowsill.
We do have our own native species (P. grandiflora) which is best grown outside or in a cold greenhouse, but the mexican varieties have the bigger leaves and flowers if you want to grow them indoors or use them for biological control.
They are excellent at controlling whitefly and were used by the Victorians in their orchid houses for this purpose. Tuck under the tomatoes or fuschias out of full sun and just see how effective they are. For more information see the care guide.