The Mediterranean flour moth larva is a very common commercial and pantry pest. It is a pest of mills and warehouses as it can clog machinery with its webs. The Mediterranean flour moth can be found on a great variety of foodstuffs in addition to flour, grain residues (insect-infected grain, broken kernels, and dust), and various whole grains. Although this insect is not as serious a pest as the Indian meal moth and some of the grain infesting beetles, it still causes clogging of machinery with its webbing, and at times causes grain mill shut-downs. Mediterranean flour moths are common moth pests of food goods in the kitchen or pantry. It is common in every part of the United States.
Mediterranean Flour Moth adult has wingspread of about 20 – 22mm and when at rest it is 10 - 14 mm long. The hind wings are dirty white while the forewings are blue-grey with transverse dark wavy bars and a row of dark spots at the tip. The larvae are white in color with a brown head and neck shield. The larvae can take on a pinkish or greenish hue and can reach a length of 15 - 20 mm. The pupa form a brown, spindle shaped cocoon approximately 9 mm.
The female lay between 100 - 700 eggs (usually 200) among the food source and usually fastens the eggs to the infested material. The eggs usually hatch in 3 - 5 days and the hatching larvae produce a lot of webbing. The young larvae confine themselves to silken tubes which are constantly spun. The larva attains full size in around 40 days. The larva pupates in or on top of the infested material (usually flour) or in cracks and crevices nearby. The life cycle can be completed in as few as 4 - 6 weeks but usually takes about 3 months.
The Mediterranean flour moth is mostly found infesting flour and meal. It has also been found infesting grain, bran, cereal products, nuts, chocolate, seeds, beans, biscuits, dried fruits and other stored foods.