The process of damselfly reproduction is fascinating and multi-faceted. When a male has successfully courted a female and is ready to mate, he must transfer a packet of sperm from his primary genitalia near the end of his abdomen, to his accessory genitalia located on the second segment of his abdomen. He then uses his claspers (anal appendages) to grab the female behind her head; this position is known as being in tandem. If he has not already transferred the packet of sperm (which may also contain some nutritional value for the female as a nuptial gift) he will do so now. The pair of damselflies will now fly in tandem to a suitable mating perch. Once in a safe spot away from rival males, the female places her genitalia on the accessory genitalia of the male (by curling her abdomen beneath her thorax and forwards) and receives the sperm. The resulting shape formed by the two insects resembles a heart, and is referred to as a copulation heart, copulation wheel, or being in cop.
The female will then use her sharp ovipositor to deposit her eggs in (often submerged) aquatic vegetation. The male will likely hover above her, or remain clasping the female behind her head in order to ward off rival males. If possible, rival males will use cups and bristles on the end of their penis to remove another male’s sperm, and replace it with their own. Damselflies have been known to perform aggregated oviposition, where multiple damselflies oviposit their eggs together.
Male and female common blue damselflies (Enallagma cyathigerum) fly in tandem.
Common blue damselflies in a copulation wheel.
A female white-legged damselfly (Platycnemis pennipes) oviposits her eggs while the male clasps her behind the head.
Aggregated oviposition on a floating piece of bark. These are white-legged damselflies (Platycnemis pennipes).