Whilst explaining “the birds and bees”, as it relates to dragonflies, might seem superfluous, the reproduction process of odonata exhibits some unusual features.
This mating formation is referred to as the copulation wheel or copulation heart. In damselflies, with their exceptionally flexible abdomens, it is very heart-shaped. This formation is unique to odonata – the dragonflies and damselflies but what’s going on?
When ready to mate, the male transfers a package of sperm from his primary genitalia at the end of his abdomen, where you might expect them to be, to his secondary genitalia which are beneath S2.
When he attaches to a female (holds her behind the head), if she is receptive, she then swings her abdomen under and round joining her genitalia with the male’s secondary genitalia so sperm transfer can take place. They are said to be in copula or in cop for short.
[Side note: if you’ll excuse the indelicacy, dragonfly rape is impossible because the female alone is in control of the sperm transfer – she can simply refuse to complete the wheel.]
This wheel/heart formation using secondary genitalia is unique to odonata. Butterflies, for example, mate back to back, as do flies.
While we’re here, there are some more details of interest.
Egg fertilization doesn’t take place at copulation time but at oviposition, egg laying time. The male’s secondary genitalia contains an organ designed to clear out any sperm that the female may be carrying from a previous mating – he wants to ensure that his genes are perpetuated rather than a rival’s.
That’s also why many odonata remain joined until oviposition has been achieved, to stop another male interceding and replacing the first male’s sperm. Some don’t actually remain joined but the male flies guard over the female while she is ovipositing. A few do oviposit solo.