Home   Gallery   About Odonata   Photographers

 

 

Odonata (Dragonflies and Damselflies)

 

Dragonflies and damselflies are predator insects, which spend the longest period of their lives as larvae, i.e. naidae in water.

 

The grown up imagoes are very good fliers, they have two pairs of transparent and elongated, equal or wings of different length with a complex net of intertwined tendons and visible cuticular swellings called pterostigmas. Their eyes are very big and spherical.

 

They are most often of very bright metal-shining colours.

 

We can often see them flying above all the watercourses, ponds, marshes, fresh and brackish waters. As they are good fliers they can also be seen far away from water.

 

The life cycle of dragonflies is incomplete. We distinguish the following stages: the grown-up specimen with wings, an egg and a larva. There is no cocoon stage.

 

They are connected with water throughout their development. The males occupy and defend their hunting territory above water against other dragonflies and allow access only to the females of their species. Their mating is unique in the world of insects as they mate in the air. A male catches a female for the upper part of chests or head and a female bends her abdomen up to the second abdominal extension of a male that carries the secondary genital opening. Being joined in such a way they make the so-called copulation ring. After the insemination the females of some species lay eggs accompanied by males or they do it alone.

 

Dragonfly and damselfly females lay the inseminated eggs directly into water or humid soil, or on parts of plants that are under water, on the water or in its vicinity. The larvae, which are the predators, come out of the inseminated eggs and they shed several times. The period spent in the larvae stage is different and it can range from a month or two to several years, depending on species. The last shedding happens out of the water. The insect with wings comes out of the larvae skin.

 

The grown-up insects live for several weeks. After mating and egg laying the winged insects die and only representatives of one of our species survive winter as grownup insects. The first occurrence of the winged insects happens during spring and the last disappearing during late autumn, which depends on weather conditions. It can be moved for several weeks ahead or back. The winged forms of some species appear in the early spring, some during summer and some during the late autumn.

 

The winged insects are also predators. They eat other insects and smaller and weaker specimens of their own order. This phenomenon is called cannibalism. They are exceptional fliers and they hunt, eat, mate, lay eggs and die in the air.

 

Based on morphological and anatomical properties, the Odonata order in Serbia can be divided into two sub-orders: equal-wing species or Zygoptera and species with different wings or Anisoptera.

 

The number of Odonata species in the world is estimated to more than 5 000 and 4 875 species have been described until now. In the territory of Serbia 61 species have been described and 51 species of such insects have been described in Vojvodina.

 

They are very important as indicators of unpolluted natural habitats and as predators of larvae and grown-up mosquitoes.

 

Odonata (vilinski konjici i device)

 

Vilinski konjici su grabljivi insekti koji najduži deo svog života provode kao larve naide u vodi.

 

Odrasli imago su veoma dobri letači, imaju dva para prozirnih i izduženih, jednakih ili različitih krila sa složenom mrežom sitnih izukrštanih žilica i upadljivim kutikularnim zadebljanjem pterostigmom. Oči su veoma velike i sferične.

 

Obojeni su najcešce veoma jarkim metalnosjajnim bojama.

 

Često ih možemo videti kako lete iznad svih vodotokova, bara, močvara, slatkih i brakičnih voda. Pošto su dobri letači mogu se sresti i veoma daleko od vode.

 

Životni ciklus vilinskih konjica je nepotpun. Razlikujemo sledeće stadijume: odraslu krilatu jedinku, jaje i larvu. Odsustvuje stadijum lutke.

Svojim razvicem vezani su za vodu. Mužjaci zauzimaju i brane svoju lovnu teritoriju iznad vode od drugih vilinskih konjica i samo ženkama svoje vrste dozvoljavaju pristup. Parenje je jedinstveno u svetu insekata i vrši se u letu. Mužjak hvata ženku za prednji deo grudi ili glavu, a ženka svoj abdomen savija do drugog abdominalnog nastavka mužjaka gde se nalazi sekundarni polni otvor. Ovako spojeni oni čine takozvani kopulacioni prsten. Nakon oplodenja, kod nekih vrsta, ženke polažu jaja u pratnji mužjaka ili same.

 

Ženke vilinskih konjica oplodena jaja polažu direktno u vodu ili vlažnu zemlju, ili na delove biljaka koje su pod vodom, na vodi ili u njenoj blizini. Iz položenih oplodenih jaja razvijaju se larve koje su predatori i koje se nekoliko puta presvlače. Period proveden u stadijumu larve različit je, i može biti od mesec-dva do nekoliko godina, zavisno od vrste. Poslednje presvlačenje je izvan vode. Iz košuljice larve ispili se krilati insekt.

 

Odrasli insekti žive nekoliko nedelja. Nakon parenja i polaganja jaja krilati insekti uginu, samo jedna naša vrsta prezimljuje kao odrastao insekt. Prvo pojavljivanje krilatih insekata je tokom proleca, i poslednje nestajanje tokom kasne jeseni i zavisi od vremenskih uslova. Ono može biti pomereno nekoliko nedelja napred ili nazad. Krilati oblici nekih vrsta pojavljuju se u rano proleće, nekih tokom leta, a nekih tokom kasne jeseni.

Krilati insekti su takode grabljivice. Hrane se drugim inektima, a i manjim i slabijim jedinkama istog reda, ova pojava naziva se kanibalizam. Izuzetni su letači, koji u letu love, jedu, pare se, polažu jaja i umiru.

 

Na osnovu morfološke i anatomske grade red Odonata Srbije se može podeliti u dva podreda: jednakokrilci ili Zygoptera, i raznokrilci ili Anisoptera.

 

Broj Odonata u svetu procenjuje se na više od 5000, a do sada je opisano 4.875 vrsta. Na teritoriji Srbije opisano je ukupno 61; a u Vojvodini 51 vrsta ovih insekata.

 

Veoma su značajni kao indikatori nezagađenih prirodnih sredina i kao predatori larvi i odraslih komaraca.

 

tekst: Svetozar Santovac

 

back to www.naturefg.com