S. Mahunka szerk.: Folia Entomologica Hungarica 56. (Budapest, 1995)

cm diameter. Dietrick (1961) designed the first suction apparatus driven by petrol engine with wide-opening (up to 0.1 m

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) which became the proto-type of the widely used D-vac. In 1990's relatively cheap hand-hold suction devices, so called 'leaf blowers' became commercially available, and were used as suction samplers by some authors (De Barro 1991, Macleod etal. 1994, Arnold 1994). In the present paper we describe a simple way of modifying a commercially available leaf blower into a hand-hold suction sampler. We also report on a preliminary study where pitfall trapping, sweep net sampling and suction sampling were carried out in an alfalfa field and a neighbouring meadow. Based on the composition of different arthropod taxa caught, a comparison is drawn between the different collection methods. MATERIALS AND METHODS Design and use of the suction sampler The sampler was modified from a commercially available leaf blower with suction outfit. It had a 2-stroke air-cooled engine that rotated a plastic fan with an operating frequency of c. 7000 rpm. The velocity of air inflow was c. 70 m/s, which resulted in moving an air volume of 10 m

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/min through the 0.01 m

2 opening of the suction attachment. The suction attachment constituted of two plastic tubes, the first attached to the engine, and the second into the first one. The only part that needed modification was the 'distal' tube of the suction attachment. The angled end of this tube was cut off in order to have a perpendicular finishing. Six holes of 10 mm in diameter were drilled at a distance of 10 mm from the edge along the perimeter. These holes were covered with strong gauze netting to let only air in from sideways. This served the purpose of creating upward air-stream in cases when the sampler was pressed tight against the ground or some other surface (Fig. la). Insects dragged by the air-flow were caught in a collecting bag made from strong linen and gauze netting. The bag was fitted between the two parts of the suction attachment (Fig. 1 b). When collecting with the suction sampler, the device was pressed against the ground or the vegetation to be collected from. While sampling the engine had to run full speed to provide the necessary suction power. This power was enough to keep all collected material in the bag in an upside-down position, which was the normal sampling position. Sampling a unit area equal to the area of the suction attachment (0.01 m

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) was done by pressing down the sampler in vertical position until it reached the ground surface. During one press-down the sampler was kept in sampling position for c. 10 seconds. Detachment of the two tube parts, in order to access the collection bag for emptying, could be done either with the engine switched off and the machine turned upside down (F. Tóth pers. comm.) or while it was running (in the later case this required the assistance of another person). Our experience showed that depending on the vegetation and soil type 10-15 such press downs were the maximum that could be carried out without loosing much suction power owing to the accumulated debris in the collecting bag. When unwanted plant material was extremely abundant (like an autumn forest, meadow after mowing, etc.) fewer press-downs per sample might be needed.