6. Collecting of Insects from the Trees Branches and Collecting Aquatic Insects

Vegetation provides large living space for insects, for example, woody trunks of plants create various biotopes. Different microclimates and conditions provide leaves and, at first sight, deadly looking barks and trunks of trees. The trapping of insects on the surface of a tree trunk and wrinkled bark is the main topic of this article. The second part of this article will cover collection of insects in a water environment.

Looking at full-grown trees in forests, man often desperately wonders, whether he is able to achieve (without destruction) only a fraction of its volume – that he is limited to study only its lower branches or tree base. It is only partially the truth.

1. Tree traps

There are apparatus which permit an examination of the vegetation of a treetop without the need to climb there. These devices are called tree traps. Each trap may look different, but the general design consists of a funnel leading to a collection bottle, and with a roof covering it all.

The collection (killing) bottle is filled with fluid which at the same time works as a bait and preservative agent – it imitates the principle of a wasp trap (Hymenoptera: Vespidae in orchards). The use of a pulley system allows for the hanging of this apparatus in a tree top. Tree traps may look like flight interception traps mentioned in the previous article. In the tree traps are mostly caught the genre of Hymenoptera.

The trap is a passive way of insect collecting. It can be made out of bagging folded more than once and then wrapped around the tree trunk and tied with string or wire. It works on the principle of providing a dark shelter, which is very attractive to an insect. The trap also catches the species that do not usually live in the tree tops, but which have used the shelter for wintering.

2. Tree bark net

On the wrinkled bark of trees live specialized insect specimens, which are otherwise nowhere to be found. A few examples which can be mentioned are Psocoptera, Hymenoptera: Formicidae, Coleoptera: Staphylinidae, Thanasimus formicarius, Raphidioptera, and Arachnida: Pseudoscorpionida.

To trap insects living in this place a tree bark net or a trap is the ideal choice. A tree bark net is an active way of insect collecting. The net can have an edge frame profile adjusted to the letter “U” or the edge of the frame can be flexible so that no gap emerges. The net is basically designed so that the long edge (flexible or “U” profiled) sits snugly against the tree trunk allowing you to brush insects into the trap from the bark.

Tree trap	Tree bark net

3. The collecting of aquatic insects

Even more specialized and unique insect specimens live in an aquatic environment. The complete difference between wet ground and aquatic streams requires insects to adapt to the local conditions. The main problem the insects had to solve was breathing under water, because their bodies are not able to breathe oxygen dissolved in the water (except larvae of some genres).

Individual genres of aquatic insect have different mechanisms which allow them to utilize the dissolved oxygen. The act of the collection of aquatic insects in comparison to the collection of terrestrial insects does not differentiate. We use an aquatic net, that is fairly similar to the entomological (butterfly) net.

The stick of an aquatic net is often made out of wood or laminate, the net is made from glass meshes. Collecting with an aquatic net is due to the water density and sedimentexacting and the moves are not that fast and deft. We use the same principle as we used during the sweeping. Collecting with an aquatic net is possible on the water surface and also under water in the water stream. Between the most often trapped insects belong larvae and adults of Coleoptera: Dytiscidae, Hemiptera: Notonetidae, Hemiptera: Gerridae, Hemiptera: Hydrometridae, and larvae of Odonata, Ephemeroptera, and Diptera: Culicidae.

Author: David Mazáč