The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera: Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were examined using both stereo and compound microscopy. These were typical of other Delphacid planthoppers in that the reproductive system was composed of two ovaries with each consisting of 11 to 13 tubular ovarioles. The ovarioles within each ovary connected via a lateral oviduct and ultimately to the other ovary via a common oviduct. Ovaries were of the telotrophic meroistic type wherein nurse cells contained within the distal germarium did not descend individually with each maturing follicle. An enlarged sac-like bursa copulatrix opened into the common oviduct just posterior to the spermatheca. The bursa copulatrix contained globular structures which we interpreted to be spermatophores. Individual follicles consisted of an inner yolk-filled oocyte (in more mature follicles) with a distinct germinal vesicle or enlarged nucleus present in the proximal region of the follicle. Each oocyte was surrounded by a single layer of cells, termed the follicular epithelium, and the entire ovariole was surrounded by a thin membranous layer, the ovariole sheath. A unique structure surrounding the most distal portion of the lateral oviduct and appearing as a loose grouping of cells which opened proximally was visible at the base of each ovariole in reproductive females. This structure, which we termed the collar, did not appear to be attached to the ovarioles or the lateral oviduct tissues and has not previously been reported in other planthopper or insect species. The continuum of ovarian development was divided into three nulliparous and three parous stages based on ovariole differentiation, presence and appearance of follicular relics, and collar length, which increased linearly with increasing numbers of ovulations. Taken together these characteristics can be used to estimate reproductive condition and number of ovulations of this biological control agent. Key Words: Eichhornia crassipes ; ovary; ovariole; follicular relics Resumen Se examino la morfologia del sistema reproductor femenino en Megamelus scutellaris Berg (Hemiptera: Delphacidae), un agente de biocontrol de Eichhornia crassipes (Mart.) Solms (Pontederiaceae), con tecnicas de microscopia optica estandar. Se examinaron los ovarios extraidos de individuos disecados en solucion salina tamponada con fosfato con microscopia estereoscopica y compuesta. Estos fueron tipicos de otros plantofilos delphacid en que el sistema reproductor estaba compuesto de 2 ovarios con cada uno consistente de 11 a 13 ovarioles tubulares. El oviducto lateral de cada ovario condujo a un oviducto comun. Los ovarios eran del tipo meroista telotrofico donde las celulas enfermeras estaban dentro del germario distal. Un bursa copulatrix de tipo saco ampliado se abre al oviducto comun justo posterior a la espermateca. La bursa copulatrix contenia estructuras globulares que interpretamos como espermatoforos. Los foliculos mas maduros contenian un ovocito lleno de yema de huevo con una vesicula germinal distinta o un nucleo ampliado presente en la region distal del foliculo. Cada ovocito estaba rodeado por una sola capa de celulas, denominada epitelio folicular, y el ovariole entero estaba rodeado por una fina capa membranosa, la vaina ovariole. Una estructura unica que rodeaba la porcion mas distal del oviducto lateral y que aparecia como un grupo suelto de celulas que se abrian proximalmente era visible en la base de cada ovariole en hembras reproductivas. Esta estructura, que denominamos el cuello, no parecia estar unida a los ovarioles ni a los tejidos laterales del oviducto y no ha sido reportada previamente en otras especies de saltamontes o insectos. Se dividio el continuo del desarrollo ovarico en 3 estadios nuliparos y 3 parosos, basados en la diferenciacion ovariole, la presencia y aparicion de reliquias foliculares y la longitud del collar, que aumento linealmente con el aumento del numero de ovulaciones. En conjunto, estas caracteristicas se pueden utilizar para estimar la condicion reproductiva y el numero de ovulaciones. Palabras Clave: Eichhornia crassipes ; ovario; ovariole; reliquias foliculares View this article in BioOne