They are variable in appearance, with the nominal subfamily Crambinae (grass moths) taking up closely folded postures on grass stems where they are inconspicuous, while other subfamilies include brightly coloured and patterned insects that rest in wing-spread attitudes.

The latest review by Munroe and Solis, in Kristensen (1999), retains the Crambidae as a full family.

Pyralidae (sister group) Pyraustinae Spilomelinae Odontiinae Linostinae Glaphyriinae Lathrotelinae Musotiminae Midilinae Schoenobiinae Acentropinae Hoploscopinae Erupinae Heliothelinae Scopariinae Crambinae Since crambids are relatively common throughout human settlements, the moths tend to affect crops and gardens, whether harmfully, beneficially or harmlessly.

Beneficial crambids include the water hyacinth moth (Niphograpta albiguttalis), used to control its host (Eichhornia crassipes),[4] the water veneer (Acentria ephemerella), a biocontrol agent used against Eurasian watermilfoil,[5] and the bamboo borer (Omphisa fuscidentalis), of which the caterpillars are used for human consumption.

), the rice white stemborer (Scirpophaga innotata), the southwestern corn borer (Diatraea grandiosella), and the grape leaffolder (Desmia maculalis).