Copitarsia consueta (Walker) is a polyphagous insect that could be a serious pest of several cultivated plants in Mexico (Gutierrez & MacGregor 1983). Recently, some aspects of reproductive behavior were studied (Rojas & Cibrian 1994). Crude extracts of the female terminal abdominal segments tested in a wind tunnel evoked in males the following behavioral acts: oriented flight, landing, wing-fanning, spreading genitalia and attempted copulation (Rojas et al. 1993). Until now, the exact location of the sex pheromone gland remained unknown. This paper provides morphological and histological evidence of putative cells involved in the production of sex pheromone of C. consueta . The insects used in this study were reared at 25 ± 2 ° C, 65 ± 5% RH, and 14:10 (L:D) photoperiod regimen on an artificial diet (Rojas et al. 1993). Virgin females 4-6 days old were anesthetized with CO 2 , the terminal portions of their abdomen extruded to a normal degree by gentle squeezing, and the abdomen ligated to keep the last segments extruded. The abdominal tips were cut off anterior to the ligation and fixed in Duboscq-Brasil (Pantin 1946) for 72 h. For scanning electron microscopy, the material was dehydrated in ethanol and critical-point dried. The tissue was mounted on metallic cylindrical stages, coated with gold and examined with a JEOL 35-C scanning electron microscope, operated at 10 Kv. For histological observations, the tissue was dehydrated in ethanol and embedded in paraffin. Serial, longitudinal and transverse sections were made at 10 μ m, stained with hematoxylin-erythrosin and mounted in Canada balsam. Photomicrographs were taken with a Zeiss photomicroscope. Analysis of the integument of the last abdominal segments suggests that two types of structures are involved in the production and release of pheromonal components. The first involves intersegmental membranes VII-VIII and VIII-IX (Fig. 1, No. 1,2) which reveal a characteristic histological structure on which the external surfaces are covered with a multitude of sharp epicuticular projections (Fig. 1, No. 4). These epicuticular projections rest over a stratum of flexible procuticle. Possible glandular cells present on this integument are similar to those found in other noctuids (Percy-Cunningham & MacDonald 1987). The pheromone producing glands in other Noctuidae are located in intersegmental membrane VIII-IX (Percy-Cunningham & MacDonald 1987). No prior study has found pheromone-producing cells in intersegmental membrane VII-VIII in this family. However, in the butterfly Argynnis addippe , the gland is located over the intersegmental membrane of abdominal segments VII-VIII (Percy & Weatherston 1971). The second structures involved in pheromone production are the two lateral cuticular sacs situated in intersegmental membrane VII-VIII (Fig. 1, No. 3). At this place the integument is invaginated at each side to form an almost spherical cavity of extremely thick cuticle. It is formed by a thick layer of lamellated procuticle and a thin layer of superficial epicuticle (Fig. 1, No. 5,6). The hypodermis of this integument is