Mothidae are tiny to small hairy or scaly long-horned suborder insects, including blood-sucking sandflies, common indoor moths and other important health pests. Their heads are small and slightly flat, and their compound eyes are far away from the left and right, without monocular eyes. The antenna is long, equal to or longer than the head and chest, and consists of 12~ 16 nodes, and the hair is long in the wheel; The jaws of mouthparts are long and tortuous, with 4 or 5 joints, short beaks and long bloodsucking ones. Thick chest and bulging back, small shield round; The foot is short or slender, and the tibial joint is endless. The base of the wing is narrow, the end is pointed or round, and it is often spindle-shaped; There are many fine hairs on the wing margin and veins, and a few have scales. The longitudinal veins of ulnar vein are numerous and obvious, at least 9 of them extend to the wing margin, and the transverse veins are few only at the base of the wing, and the basal chamber is short. How short or incomplete is Sc? R is 4 or 5, M is 3 or 4, Cu is only 1, and A is short or degenerate. The abdomen is tubular, with 6~8 nodules. The male genitals are developed and exposed, and the female ovipositor is prominent. Commonly known as fluttering moths.

Larvae is slender and cylindrical, full-headed, footless, with petals or posterior petals at both ends. Body 12~ 16, there are many ossified fragments on the back of the body. The ventral surface usually protrudes to help it move, and the valve at the back is located on a short tube. The body is bristly or rod-shaped, and the abdomen often has long hair or brushes. Aquatic larvae also have tracheal gills and sucker-like attachment structures. Most larvae are saprophytic or dung-eating, living in

Rotten wood, rotten grass and mud, some of which live in sewers, are common indoors after eclosion.

Moth adults are very common in outdoor humid environment except indoors, and some live in termite nests, rat holes, animal holes and so on. In addition to sewage, aquatic people are also under still water or waterfalls. When adults of moths rest, their wings tend to tilt upward or backward in a roof shape, with hairs or scales on them, which are similar to small moths, so they are called moths, moth flies, hairy flies and so on. The word "Nymphalia" has been used in vein-winged insects for a long time, but the names of Nymphalia and Nymphalia are the family names of Neuroptera and should not be used any more. Sandfly is used to it.

Short and thick, hairy, the wings are spindle-shaped, inclined like a small moth, and there are different colors of hair stripes on the wings. The radial branch Rs of pterygoid vein is divided into four branches, and the end of elbow vein Cu 1 is longer and extends parallel to middle vein M4. Short mouth, no blood. There are many kinds of subfamilies, adults often appear in houses, and larvae breed in sewers.