INTRODUCTION. The Indianmeal moth was given its common name by an early entomologist (Asa Fitch) who found it feeding on cornmeal (Indian meal). It is probably the most encountered pest of stored products found in the home and in grocery stores in the United States. Of Old World origin, it is now found worldwide.

RECOGNITION. Adults with wingspread (wing tip to wing tip) about 5/8-3/4" (16-20 mm). Wings pale gray but front wing with outer 2/3's reddish brown with a coppery luster.

(actual size)

Mature larva usually about 1/2" (range 9-19 mm) long. Usually dirty white but color may vary to a greenish or pinkish or brownish hue depending on its food, with head and prothratic plate/shield yellowish bron to reddish brown. With 5 pairs of well-developed prolegs on abdomen and each bearing crochets (hooks).

Prespiracular tubercule (wartlike area between spiracle and front edge of segment) of prothorax with 2 setae (hairs). Tubercule VI on mesothorax (wartlike area near and above leg) with one seta (hair). Body without pinnicula (dark or pale wartlike area at base of hairs or setae) on mesothorax, and 1st 9 abdominal segments.

Rim around spiracles of about even thickness.

SIMILAR GROUPS.
 

• Carpet/tapestry moth (Trichophaga tapetzella) with basal 1/3 of front wing dark brown to black,, remainder of wing white mottled with gray and black.
• Other small moths lack front wing with basal 1/3 pale and reainder dark, wing span of about 5/8-3/4" (16-19 mm), and/or hind wing broader than front wing and fringed with long hairlike scales.

BIOLOGY. Chiefly at night, the female lays 100-400 eggs, singly or in small groups, on the larval food material during a period of 1-18 days. Upon hatching, the larva establishes itself in a crevice of the food material. It feeds in or near a tunnellike case it has webbed together of frass or silk. The larval period lasts 13-288 days, depending primarily on temperature and food availability. When the last instar larva is ready to pupate, it leaves the food and wanders about until a suitable pupation site is found. There are usually 4-6 generations per year (range 4-8), with the life cycle (egg to egg) typically requiring 25-135 days (range 25-305).

HABITS. The adults cause no damage. The larvae are surface feeders and generally produce a lot of webbing throughout the infested part of the materials. They are general feeders and attack grain and grain products, a wide vriety of dried fruits, seeds, nuts, graham crackers, powdered milk, biscuits, chocolate, candies, dried red peppers, dried dog food, and bird seed. They are very destructive wherever dried fruits are stored. Preferred are the coarser grades of flour such as whole wheat, graham flour, and cornmeal, but they can breed in shelled or ear corn.

When the larvae wander about looking for pupation sites in homes, they are often mistaken for clothes moth larvae. Likewise, when the moths are flying, they are also mistaken for clothes moths. Adults are attracted to light.

CONTROL. follow the standard control procedures for stored product pests but remember that pupation takes place away from the infested food material.