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- Robber flies of Germany -
Key      Catalogue      Comparisons      [Notes]      Terminology     



 -   General
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  contents & layout
  & copyright:
  Fritz Geller-Grimm



Malaise-trap For the study of robber flies it is imperative to build a comparative collection. To efficiently collect many species in a short amount of time, it is helpful to learn about their biology (cf. MUSSO, 1978).
A joint field trip with an experienced colleague could be very helpful. For example, a few years ago I met Mr. Milan Hradský and we shared our experiences. He explained to me that he often collects robber flies in the evening, when the flies are less active and rest on the ground. Nevertheless I cannot use his advice because I am, as the flies, usually tired after searching for them all day.
Because there are no general rules for catching Asilidae, a creative approach is necessary. The following equipment can be helpful for collecting:

  • insect nets (with a strong frame and fine net curtain)
  • Mailaise traps
  • pan traps on the ground and on fallen trees (usually yellow-coloured)
  • emergence traps of different shape
Robber flies lie in wait for their prey at special resting points. This can be advantageous for the collector. If the first catching attempt is unsuccessful, it can often be repeated after some time, because the flies occasionally come back to the same place.
Resting points are: bare soil without plants, tips of grass and leaves, dry branches, stones, sunny tree trunks, etc. (cf. research).

open pathes and edges of forests  bushes and dry branches  open sand soil

It is worthwhile to keep a diary about the expedition and record special information on the behavior of the animals, which will shed more light on their biology.

Dysmachus trigonus - with prey Because of the fine tomentum of several species, it is absolutely necessary to protect the collected flies against humidity. This can be achieved by putting a lot of dry paper inside the collecting jar and to using only specific poisons like ethyl acetate.
In addition, some specimens should be killed and preserved in 95% ethanol, so they can be used for DNA analysis as well. After killing, it is necessary to prepare them very carefully. It is important to open the wings slightly and fold the legs under the body. Sometimes it is helpful to dissect the genitalia. To separate the genitalia it is the best to cut the end of the abdomen between the 5th and 6th segment. Then cook the segments in a small glass-tube in 10% KOH for some minutes. With the aid of a fine pointed forceps and microscissors it is possible to dissect the different structures. The genitalia should always be kept with the insect. The best way to store dissected genitalia is in glycerin in a plastic microvial which can be mounted on the same pin as the fly.
The specimen label should contain the following information: Country, province, distance to the next bigger city, date, geographical coordinates and further notes, like habitat and behavior.

In principle it is advisable to obey the nature conservation laws of the different countries you are going to collect in. Some countries do not allow insects to be collected without permission and it is recommended to ask for written permission before attempting to collect.









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