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Field Recording & CollectionCollecting TechniquesAs
with many insect groups, there are several techniques that can be used
for
collecting leafhoppers and planthoppers. Everyone has their favourite
and most
people employ different techniques according to the circumstances. The
following account outlines the uses and relative merits of some of the
most
commonly used pieces of equipment.
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Sweep Net
A sweep net is a particularly robust type of net used to dislodge and collect insects from vegetation. It must have a reinforced rim to withstand the impact of jarring against plants and the net bag should be constructed from a natural fibre or synthetic cloth material that is similarly durable. Sweep netting is almost certainly the most widely used method for collecting leafhoppers off vegetation. The principal advantage of a sweep net is that it is easy to use, large numbers of leafhoppers can be caught and extensive areas of ground can be covered quickly. An important drawback is that it cannot be used if the vegetation is wet, flattened or very short and the netting can easily snag on brambles and thorny bushes. Likewise, it is difficult to use on some trees or very tall or dense vegetation (e.g. reedbeds or grassy tussocks) and species that live very close to the ground will tend to be passed over. Nevertheless, it is easily the most versatile piece of equipment to have and can be used in virtually all habitats. |
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Beating Tray
A beating tray is simply a large cloth sheet stretched flat over a frame. It is held under the branch of a tree which is then given a couple of sharp taps with a ‘beating stick’. The idea is that insects on the leaves or stems of the branch are dislodged and fall down onto the tray from where they can be collected for examination. It is important to realise that any insects not immediately dislodged in this way will tighten their grip in response to the jarring, so any further thrashing of the branch will probably be fruitless. Unlike many other insects such as beetles, any leafhoppers knocked onto a beating tray will recover quickly and attempt to fly off, so they have to be placed in a collection tube quickly before they escape. Beating trays are useful for collecting off tree branches and bushes which are too woody for a sweep net. |
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Suction sampler
Over the years, various devices have been developed for extracting insects from vegetation using some sort of suction apparatus. It is easy to construct one of these by modifying a petrol-driven garden leaf-blower. All that is needed is to insert a fine-mesh bag into the suction tube and secure it round the inlet with rubber bands. For safety, it is advisable also to fix a piece of large-mesh wire netting inside the base of the inlet tube to prevent the bag from being sucked into the fan if it comes loose. Suction devices such as this can be extremely efficient at extracting leafhoppers and planthoppers from very dense vegetation (e.g. grass tussocks) and tall plants that are difficult to sweep (e.g. reeds). They are also excellent at collecting species that typically live close to the ground and therefore get missed by sweep netting. Contrary to most people’s expectations, the insects that are sucked up generally survive the experience unharmed! |
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Pitfall trap
A pitfall trap can be made from any collection vessel (glass, plastic, metal), typically 6-7 cm in diameter and 10 cm deep, set into the soil such that its rim is level with the soil surface. Invertebrates that are active on the soil surface or very close to the ground fall into the trap and are unable to escape. The trap is normally partly filled with a preserving fluid to ensure that catches do not decompose if the trap is left in place for a week or more. Pitfall traps are not widely used
for collecting leafhopper and planthoppers, but they can nevertheless
reveal
interesting species. Leafhoppers are often part of the
‘bycatch’ in pitfall
trap surveys of spiders or ground beetles. They are especially useful
for
collecting certain genera that appear to live very close to the soil
surface,
such as Agallia, Aphrodes,
Eurysa, Delphacodes,
Macustus, Megamelodes,
Megophthalmus, Streptanus, Stroggylocephalus
and Ulopa. Another
interesting
feature of pitfall trap catches is that they often contain a high
proportion of
male specimens.
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Malaise trap
A Malaise trap looks like an open sided tent, with dark vertical walls and a white roof to encourage insects to move upwards and be funnelled into a collection bottle mounted at the apex of the tent’s roof. Malaise traps tend to be used mainly for collecting Diptera and Hymenoptera. However, they do also regularly trap leafhoppers and planthoppers, sometimes in great abundance. They can be left out for considerable periods of time, although they are prone to vandalism if set up in public places and are vulnerable to high winds. |
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Hand
searching Anyone
interested in leafhoppers
and planthoppers should not discount the simple technique of searching
known
host plants by hand. Turning over leaves to inspect the undersides can
often
reveal typhlocybine leafhoppers, both as adults and nymphs; the best
approach
is to look first for white stippling on the upper leaf surface which is
evidence of their feeding damage. Taking the trouble to search for and
examine
leafhoppers that are feeding undisturbed can reveal useful information
about
their preferred food plants, feeding sites and micro-habitats, in a way
that
disruptive collection techniques like sweep netting cannot.
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Aspirator/Pooter Once in the sweep net or on the beating tray, leafhoppers need to be transferred to some sort of collection vessel to be inspected more closely. Because they readily jump and fly when disturbed, it is usually difficult to do this by coaxing them into a sample tube. Instead, the insect can be sucked into a collection chamber in a device called an aspirator (sometimes known as a ‘pooter’). The chamber can hold large samples of insects before it needs to be emptied. Novices quickly learn that, because leafhoppers and planthoppers jump forwards, they are most successfully caught by approaching them from the front with the aspirator inlet tube. |
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Equipment
suppliers The following entomological suppliers sell most of the equipment described above. Leaf-blowers that can be converted to insect suction samplers are sold in garden centres and DIY stores (although it is important to select one that is petrol-driven rather than powered by mains electricity).
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