The Pyralidae, commonly called pyralid moths, snout moths or grass moths, are a family of Lepidoptera in the ditrysian superfamily Pyraloidea. In many (particularly older) classifications, the grass moths (Crambidae) are included in the Pyralidae as a subfamily, making the combined group one of the largest families in the Lepidoptera. The latest review by Eugene G. Munroe and Maria Alma Solis retain the Crambidae as a full family of Pyraloidea.

The wingspans for small and medium-sized species are usually between 9 and 37 mm (0.35 and 1.46 in) with variable morphological features.

It is a diverse group, with more than 6,000 species described worldwide, and more than 600 species in America north of Mexico, comprising the third largest moth family in North America. At least 42 species have been recorded from North Dakota in the subfamilies of Pyralidae.

Most of these small moths are inconspicuous. Many are economically important pests, including waxworms, which are the caterpillar larvae of the greater (Galleria mellonella) and lesser (Achroia grisella) wax moths (subfamily Galleriinae). They are natively pests of beehives, but are bred indoors in enormous numbers as live food for small reptile and bird pets and similar animals. They are also used as fishing bait for trout fishing.

Other notable snout moth pests relevant for their larval hosts include:

The European corn borer (Ostrinia nubilalis) and southern cornstalk borer (Diatraea crambidoides), formerly considered snout moths, are placed in the Crambidae which, as noted above, are usually regarded as a separate family today.

Five subfamilies are generally recognized in the Pyralidae today. The Acentropinae (= Nymphulinae), occasionally still placed here, do indeed seem to belong in the Crambidae.

The snout moth subfamilies are, listed in the presumed phylogenetic sequence from the most primitive to the most advanced: