Oct 16, 2013

Catching insects

Franke Scrub was a hive of activity last weekend, with approximately fifty people gathering there to study its insects.
Studying involves catching, and while there were undoubtedly plenty of insects left at the end of the day, samples of a huge variety of them were captured, to be sorted, counted, and further studied.
The activity was put together by the Friends of Franke Scrub, whose aim was to create a basic record of the insects to be found there. Besides giving us our first detailed information of what currently present, the insects were collected by scientific (therefore repeatable) techniques, enabling comparisons to be made in the future. Insects were trapped on the Scrub edges, under its canopy, and in and around the dam on the property next door.
Insect variety is a very good indicator of the overall health of an environment. We can hope that with future nurturing of Franke Scrub we might see improvements and increases in the variety of insects, because this would tell us that the ecology is in robust good health. There is also the possibility, of course, that future environmental stresses and will be reflected in our favourite patch of scrub by decline in the insect variety. Let’s hope not!
Community members joined in the activities, and were helped by Christine Lambkin, curator of insects at the Queensland Museum, to use six different methods of trapping. Another four methods were demonstrated by members of the Queensland Entomological Society, who were collecting for the purposes of their own studies, and several other methods were used by students from the Queensland University.
Collecting methods ranged from the simple use of dishes filled with water and detergent - four different colours of dish, to attract different kinds of insects - to the use of light sheets at night.
The afternoon was spend identifying (to order level), sorting and counting the insects caught by community members. The results were analysed for statistical richness and evenness, and results from two sites within the scrub were compared.
A few points of interest were:
Insects (such as mayflies) which occur in Franke Scrub as a result of the proximity of the dam were also found during the day’s activities. These demonstrate what an important contribution to Franke Scrub’s environment is made by the presence of permanent water.
A butterfly which we have not recorded before – the satin azure Ogyris amaryllis – was found. This adds to Franke Scrub’s list of the butterflies which breed on its mistletoes, demonstrating that Franke Scrub is making a contribution to a healthy local butterfly population.

Various insects which breed on our local native plant species were found. We live in a time of progressive clearance of the local vegetation, and the rate is stepping up with our growing population. Reserves like Franke Scrub are of ever-increasing importance as refuges for all the fauna which depend on the plants native to our part of Australia.

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