2019

Dragonflies, the Insect Hunters

Every summer, whether we want it or not, we notice these animals. Many of us even feel them “on our own skin”. These animals are insects. And summer is the real insect time.

Some people like insects, but most of us don't. What are the main enemies of insects? First, it is the negative impact of a diverse human activity on the majority of insects. So we, the human beings, are the main enemies of the insect class. But who, apart from us and unfavourable meteorological conditions, are the main natural enemies of insects? How to answer such a question? Most of us first think about birds and spiders. Many would think about frogs, perhaps, toads maybe - lizards ... Some more knowledgeable will not forget about the organisms that cause insect diseases. Hopefully, many species of mammals or animals are not forgotten. Fishermen will definitely mention fish. But who are the main or the most important?! Other insects are the main enemies of insects. Moreover, there is a small number of insect species that feed exclusively on other insects. Dragonflies are typical insectivora or insect eaters.

Dragonflies, the main characters of this story, have been recognized as primitive creatures. Why are they considered primitive?! Because modern dragonflies are only little different from their ancient ancestors who lived on Earth more than 350 million years ago.

The dragonfly is very easy to recognise. It has an elongated belly consisting of 11 stages, two pairs of long wings, a head connected to its chest. The biggest part of its head is made up of two big eyes consisting of thousands of small eyelets. All in all - it is amazing! However, dragonflies cannot turn their eyes. But they can turn their heads for 180 degrees. The eye structure and layout allow the head to turn, the total field of vision extends over 300 degrees. This is of great importance when hunting insects.

Adult dragonflies feed exclusively on insects. Other small creatures are casual on the dragonfly menu.

More than 6500 species of dragonflies have been discovered worldwide.

All dragonflies are similar. Differentiating specific species is not an easy task. The possibility of making a mistake in their determination is even bigger because of the fact that the colouring of the body of the males differs from that of females for the majority of species; moreover, the colouring may differ also depending on the age of the insect.

Sixty-three species of dragonflies have so far been found in Latvia. And perhaps there are even more of them.

For those who have a desire to get to know (learn to recognize) different species of dragonflies living in our country, should read the fundamental book by Mārtiņš Kalniņš, LVM Environmental Planning Specialist, SPĀRES (ODONATA) LATVIJĀ” (DRAGONFLIES (ODONATA) IN LATVIA”.

Odonata is divided into Zygoptera and Anisoptera.

Zygoptera living in Latvia are of small size, with a relatively long belly. Both pairs of insect wings are of the same size and shape. Their flight is slow, to some extent it is like a butterfly flight. Being slow and incapable of manoeuvring, these dragonflies feed by “picking up” food from the ground and “nibbling” small insects from plants. When they do not fly, these dragonflies keep their wings closed or only partially expanded.

In turn, Anisoptera are very good flyers - some of the fastest flying insects in the world.
The four wings of the insect are not the same - the wings of the rear pair are larger, as their base is wider than the base of the front pair wings. Dragonflies mostly catch flying objects. Most of these dragonflies are of ordinary size, so it goes without saying that they can afford to attack very large and powerful victims (even wasps). They are hunters! When they are not flying, the wings of these insects are almost always spread.

Dragonflies like to live near waters. However, you should not be surprised to find large quantities of these slender insects far away from lakes, rivers, streams, swamps, ponds, ditches and other water bodies. In this context, we must not forget the specific phenomenon - mass flights of certain species of dragonflies.

Dragonflies are very busy on warm, sunny days. They protect their feeding areas from their competitors. When they find their partner and mate, females can lay eggs in the water, where their larvae hatch later. They grow and develop in the water for a long time, some in northern Europe even for up to 5 years (in Latvian waters 1-2 years), until they are ready to turn from a walking underwater creature to a flying terrestrial being. Dragonflies are evolving with incomplete transformation - there is no pupa stage in their development. The larva immediately turns into an adult insect - gets out of the water and crawls out of the shell.

When you are at a water body, take a look at the empty casings from which the young dragonflies have developed. You will find out what their larvae look like.