Jewelwing damselfly (Calopteryx splendens)

Piero Fariselli

Calopteryx splendens mating in early morning (Reno river, La Panfilia Italy)

When I was a very young child, my father used to bring me at the nearby Reno river that was full of marvelous creature to discover. Among them I remember very well what we called “metallic damselflies”. However, just in the middle of the seventies the river was gone: its original wonderful sand dunes were dredged up for building houses and the water was used to convey the waste to the sea. Once growth I spent several time observing those metallic creatures in the cleaner creeks of the nearby hills.

Last year, with my great happiness I discovered that the metallic damselflies had come back into a tiny portion of my river. Thus, I spent all my free time observing them (from May to September). It turned out that they were Calopteryx splendens commonly known as jewelwing or banded damselflies. Although they are very well studied creatures and it is easy to find a lot of information (in books, articles and on the web), the direct observation was not only an incredible joy but also a source of new knowledge to me.

Actually, from the books or web pages such as www.arkive.org, you may learn that before to become damselflies, they spend two whole winter under the water in the larval state. As all the other damselflies they are carnivores also as larvae and move through aquatic plants in search of possible preys. The eggs take around 14 days to hatch.

Once molted, they reach the sexual maturity in about ten days and they are very active from May and the end of September. Depending of their behavior, in the literature males are classified in two different categories: a) the “territory-holding males” that defend a territory around suitable egg-laying site, b) “perching males” that try to mate with any female that passes by. The territory-holding males normally perch on vegetation to control the territory and they also actively court females with a fluttering display flight. In some cases the males fight over a territory with a series of stereotypical flights inviting possible spouses. After mating, females lay eggs (oviposit) alone, often placing the eggs into submerged vegetation.

Although this summary is perfectly correct, as any things in biology it is just a succinct approximation of the complex reality. In the months of my observation I noticed that these patterns are more plastic. Although I have not performed a truly quantitative analysis (with marked captures), I have recorded on a paper and with the camera interesting aspects of their behaviour. Lately, I found that the same behavior was previously detected while studying the cousin specie C. haemorrhoidalis (Cordero 1999).

The first thing that I noticed is the fact that there are difference of behavior in the observation at early and in the late morning. Moreover, the sexual behavior changed from locations where there was a low density of males to the ones with high population density.

In practice, a single male could have been both a territory-holder at early morning or in low density population, but he could switch to become a perching-male later when there are too many fellows around.

It is true that the female oviposit alone but usually the mating male defends her from the harassment of perching males. This is accomplished guarding the female at few inches of distance on a floating leaf. When the density of the intruders becomes higher the male start flying over the ovipositing female patrolling the territory. I have observed fierce fighting between males in this situation with the clear attempt to sink the adversary in the water. However, when the number of competing males is too high no one tries to defend the territory and all male start fetching any possible female passing by. This does not mean that after the copulation the male does not protect the female, on the contrary the defense of the female is attempted both after forced or courtship matings.

In some cases I observed the protecting male changing his habit and start protecting the female while oviposing by perching directly on the female wings! This behaviour that prevent forced fetching was only observed recently in another species (C. haemorrhoidalis, Cordero 1999) and was named “contact guarding”. Although, this way of protecting the females is far more efficient in high density population, contact guarding does not guarantee the result. In some cases I noticed the intruder males flying against the contact-guarding male like kamikazes. These attacks usually end up with a great brawl into the water.

It is worth noticing that in the banded damselflies the females have to cooperate in order to copulate, since they have to rise their abdomen till the correct position. So, the question is why don’t they avoid superfluous mating? I noticed that when a female tries to lay eggs in high density population, the males invariably tend to pick up her in a forced tandem while she invariably refuses. However, when there are too many bullies around she has only four possibilities to escape: 1) hide in a safe place to lay the eggs, 2) lay eggs in the same place another female is oviposing, 3) submerging completely and oviposing under the water, 4) accept matings and hoping that the new male will be able to defend her better.

Actually, I observed that a poor lady had to mate three times before she found a good chap that managed, with contact guarding, to provide her some minutes for oviposing.

It is also interesting the fact that a guarding male protects any females that lay eggs in that territory. It seems that he is not able to distinguish the females on which he copulated. We may also suppose that, given the high promiscuity of the jewelwing damselflies it is probably that the guarding male had mated at least once with any of the flying females.

The strategy of submerging completely, was new to me. In the first days the density of males was not so high so I observed oviposing only submerging the tip of the abdomen. But in the late July and in August a lot of females were diving. The first time I noticed one of them I though she was going to dead because of the harassment of the males. So I gently took out the lady from the water. However, instead of an expected thankful behavior, she was very upset and just staring directly on my eyes she flew away over my head at high speed. Incredibly she was completely dry! I am sure that in her look she was saying “ another stupid male!”.

Males of jewelwing damselflies adopt two different mating strategies. In low male density they fight for the territories in which the females can find attractive places to lay eggs. The winner land owner perches on a twig defending the position (bottom). The territory owner displays his wings opening and closing them indicating the possession to possible intruders or even to other animals including humans (bottom). When there is a high male density the defense of the land is useless and all males perch on twigs looking for any passing females (top)

The accepting females fly most frequently (and non randomly) over the site they eventually utilize as oviposition substrate guarded by territorial males. Once a female accepts the male court, he grabs her with the tips of the abdomen and they fly in tandem on a nearby vegetation to mate (top). To mate the female has to cooperate by raising her abdomen to allow intromission (bottom).

After the copulation both sexes separate and the female flies in the selected place to lay the eggs under the constant guard of the male. Usually the male stay at few centimeters on a twig or on a floating leaf. The jewelwing damselflies do not lay the eggs free into the water but insert them in the leaves of the aquatic vegetation.

Guarding male on a leaf (top) and female that is ending her oviposition (bottom)

The females of the jewelwing damselflies are incredible divers. The can submerge completely and walk under the water surface for several minutes. After the oviposition they can go out of the water and fly away almost dry. I notice that they tend submerging when there are a high male density. In this way the female can escape the harassment of the competing males.

When the individual density becomes high the guarding males start flying on the oviposing female trying to prevent the female fetching by intruders. He flies over the female fighting against any other approaching fellows.

Here some other patrolling flights

Males that do not have the posses of a territory or in the case of high density population, the males commonly grasp ovipositing females and apparently force copulations. The fetching male has to be very fast by jumping over the opivosing female (top) and capturing her by locking his cerci on her neck (bottom).

Usually the oviposing female refuse the copulation by opening their wings and preventing the formation of the tandem(top). Nevertheless, when there are a strong male competition and the harassment of the males are high the females tend to accept the copulation (bottom). It has been noted that females mated more times if they experienced higher male harassment during oviposition, and at low density second and subsequent matings were more likely to be forced. It seems that in this way females gain more by accepting copulation than by resisting. Furthermore, females probably benefit from new matings because males defend their mates after both forced or courtship matings, providing some minutes to the female for laying the eggs. Females might trade copulations for male protection, because under extreme population density harassment by males is so intense that they can impede oviposition.

Here a fast male fetched an oviposing female while a second tried to do the same.

When the competition is very high some males guarded females after forced or courtship copulations using the “contact guarding”, by maintaining a physical contact with their mate. This is accomplished by perching on her wings (top). This behaviour is far more effective than using the traditional guarding because in high density it is impossible to impede forced tandem just by chasing the intruders. This behaviour was observed for the first time in Calopterix haemorrhoidalis in 1999 (Cordero J. Insect Behavior).

However, the males compete strongly and in some cases the intruders can jump over the contact-guarding male creating real brawls (bottom).

The food requirement is an essential ingredient to sustain the strong mating activity. Jewelwing damselflies are great predators and usually jump over any kind of animals of the appropriate size. They capture the preys in flight then land on a twig or leaf to quietly consume the food. Moreover, very luckily for us jewelwing damselflies are able to eat also the insect pest Metcalfa pruinosa that was accidentally introduced in Europe from the USA (top).

The Calopteryx flight is very elegant and some people have mistaken the males for butterfly. Although not as faster as some dragonflies jewelwing damselflies can be very able in their flying, especially when the male are dogfighting in air. The normal speed is however about one meter per second, that means that a time shorter than 1/1000 of second is needed to freeze their wings in a close-up picture.

The Author:

Piero Fariselli is a researcher at the Dept. of Biology University of Bologna Italy. Although his research concerns computational and theoretical stuff, he has been always attracted by the living animals, especially the neglected ones. He spends as much as possible of his spare time as voyeur of arthropods and herptiles equipped with his camera.