PEET - Austral Staphylinidae

Methods | Collecting Methods for Staphylinidae and other Staphylinoidea | Indirect Collection Methods: Flight Intercept Traps (FITs)

This method has been described in detail by Peck & Davies (1980). When used at ground level, an FIT generally produces the most staphylinid specimens and species - a reflection of the concentration of Coleoptera activity in the lower forest layers (e.g. Moeed & Meads 1984, Hammond 1990, Hill & Cermack 1997). A detailed description of our FIT design, materials, and operation can be downloaded here. The trap is a polyester mesh net ca. 2 m x 1 m (6 ft x 3 ft) suspended over trays holding collecting fluid (propylene glycol/water mixture). A polyethylene cover helps prevent flooding and, to a lesser extent, keeps debris from accumulating in the trays. The FIT concept is rather simple in principle – many flying insects, and particularly beetles, will collide with the netting (which is painted matte black to make it less visible) and fall into the trays where they are preserved.

When searching for an appropriate trap site we look for certain habitat attributes - usually some big old trees, lots of dead wood, a moderately open canopy, and at least patches of relatively clear understory. When we find a good area, we try to identify a possible flight path in a relatively flat patch. Flying insects tend to fly where they are unobstructed by vegetation, hence this aspect of trap placement is important for maximizing diversity and abundance. In addition to desirable habitat attributes, trap security is another important aspect of installation. It is essential that the trap is located away from trails so it is out of immediate view. This helps prevent trap disturbance from the public. We usually attach a label to the trap explaining its purpose and ownership in the event that curious individuals find it – this may help prevent interference. We are also cautious not to place traps in areas that appear to be well-frequented animal tracks – a definite issue in South Africa and many other places!

Once we have decided on a suitable trap site, the work begins. Being careful not to disturb major tree roots, a trowel or small shovel is used to clear a shallow ditch where the trays are placed end-to-end. Surrounding soil is compacted around the edges to reduce the risk of wind or small mammals tipping the pans over. The trays then also operate to some extent as a line of pitfall traps. After this, the bottom of the netting is anchored with stakes and the top attached to the poles, which are guyed out with nylon cord. Finally, the rain cover strings are anchored. Once erected, adding 1-2 cm of trap fluid to each tray activates the trap. Often many insects are observed in the trays before we even leave the trap site! Here is part of a sample from Chile.

Malaise traps are another commonly used flight interception trap, which works on the opposite principle – many flying insects tend to move up when a barrier is encountered, and these are captured in a collecting jar positioned at the highest point of the trap. We, and others (e.g. Hammond 1990, Lawton et al. 1998) have found flight intercept traps to be much better than Malaise traps for collecting both staphylinids and beetles in general. Although FITs are generally preferred amongst coleopterists, quantitative data from austral ecosystems comparing the catches of FIT pans and Malaise collecting jars are currently lacking (but see Hosking 1979 and Peck 2002), and it would be of interest to know the magnitude of the difference.

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