Nepticulidae, the pygmy moth family, is composed of minute, leaf-mining moths. The family includes the world's smallest moth, with a wingspan of only 2.5 mm, according to the Florida Museum of Natural History. Larger species have wingspans of 5 mm. The adults lay eggs on the leaves of such trees as birch or willows. Each species has a favorite type of tree. The tiny larva eats its way into the leaf, tunneling through the leaf's interior, just as a miner tunnels through the earth. Other moth families that contain small leaf-mining species are Gracillariidae, Lyonetiidae and Opostegidae. Moths of the family Opostegidae are called eye-cap moths because of the prominent coverings on their compound eyes. Some eye-cap moths bore into stems instead of mining leaves.
The family Pyralidae contains more than 1000 species. Plodia interpunctella, the Indian meal moth, belongs to this large group of insects. It ranges from 18 to 20 mm, according to the University of Ohio Department of Entomology. It infests such foods as rice, cornmeal and dates, causing spoilage. It is also called the pantry moth because of its habit of entering houses and flying near the types of food it eats. Many pyralid moths have aquatic larvae that feed on such plants as pondweed. One species feeds on cactus.
Another type of small moths attacks fabrics. The family Tineidae includes the clothes moth, Tineola bisselliella. The larva of this moth manufactures a silk web as it feeds among such clothes as woolen goods. In contrast, Tinea pellionella, another clothes moth of the same family, makes a silk case and carries it along as it moves about and feeds. Other tineid moths prefer different kinds of food. Trichophaga tapetzella attacks carpets, but most family members feed on fungi or detritus.
A mutually beneficial relationship exists between yucca plants and small moths of the family Prodoxidae. A fertilized prodoxid female of the genus Tegeticula gathers pollen from one yucca flower and then pollinates the flower of another yucca plant. Using her sharp ovipositor, she then injects her eggs into ovarian tissue of the pollinated flower. When the eggs hatch, the larvae eat some of the seeds but leave others to grow a new generation of yuccas. Two exceptional Tegeticula species do not pollinate but lay their eggs in yucca flowers pollinated by a moth of a sister species. Other prodoxid moths that pollinate yucca in a similar fashion belong to the genus Parategeticula, but these moths inject their eggs into floral tissue instead of the ovary. The hatching larvae must tunnel into the ovary to get at the seeds. Moths of the related genus Prodoxus also deposit eggs in yucca tissue, but these moths do not pollinate the yucca, and the larvae eat sterile floral tissue but not the seeds, according to the article "Yucca and Yucca Moths" by Laura Hebert.