Generalised Female Reproductive System

diagram of the female insect reproductive system

The female reproductive system consists of a pair of ovaries which are subdivided into smaller units called ovarioles, where the eggs are produced. During egg production (called oogenesis), the germ cells in the germarium divide by mitosis to form oocytes (eggs). The oocytes undergo meiosis and continue to increase in size by absorbing yolk produced by adjacent cells. As the oocytes grow they are pushed downward by the continual cell division in the germarium. Thus the oocytes form chains, with the youngest/smallest cells at the top and mature/large cells at the bottom.

Once mature, an egg leaves the ovary via the lateral oviduct and continues through the common oviduct which opens into a genital chamber (called the bursa copulatrix). This is where the male deposits his spermatophore during copulation. The female uses peristaltic contractions to move the spermatophore into the spermatheca, where it is stored until it is needed. The spermathecal gland produces nutrients in order to keep the sperm alive in the spermatheca, where sperm can survive for weeks, months or even years.

When the egg enters the genital chamber it passes across the spermatheca and stimulates the release of sperm cells onto the egg surface. The sperm cells enter the egg through the micropyle, a small opening on the egg surface, and when the nuclei of sperm and egg fuse, the egg is fertilised. Oviposition (egg laying) soon takes place following fertilisation.