How entomologists catch insects, spiders and other creepy crawlies
Rolling, tearing, barking, digging, beating, sweeping, trapping – this is not a description of animal misbehavior, but rather a list of some of the techniques used by entomologists to catch the objects of their research. Tools of the trade include hands, pooters, forceps, plastic bags, a headlamp for night work, a beating stick and beating sheet, a knife, hand rake, trowel, shovel, nets, pitfall traps and even a spoon.
Entomologists study terrestrial arthropods. "Arthropoda" is the scientific name given to animals that have an external skeleton and jointed legs. It is a huge group that includes both marine groups such as crustaceans (crabs, shrimp, and their relatives) and land-dwellers such as insects, spiders, and related species.
So how do entomologists catch beetles, butterflies, bees, wasps, moths, flies, spiders, scorpions, millipedes, centipedes, grasshoppers, crickets, ticks, fleas, and the vast assortment of other terrestrial arthropods? They pursue their quarry in all types of habitats, both day and night. Many times the animal can be caught by hand or with forceps (tweezers). A special device called a pooter is used to suck up small specimens of many different types. A pooter is a piece of long flexible tubing; one end goes in the collector’s mouth and the other end has a short stiff tube which is placed above the specimen; the collector inhales, sucking the specimen into the stiff tube, and a piece of fine screening where the stiff tube joins the flexible tube keeps the specimen from getting into the collector’s mouth – a very important piece of the pooter! After being sucked into the pooter, the specimen can be expelled into a collecting container.
For larger animals like spiders or millipedes, the collector can wear a Ziploc™ bag like a glove and put their hand over the specimen to catch it. A lot of careful searching has to be done to find specimens, big or small, and they are frequently hidden out of sight. Barking (looking under the bark of dead trees) frequently reveals hidden animals, as does rolling over logs or stones, or breaking apart stumps.
Another effective way to catch arthropods is to knock them out of the bushes or trees that they are in. This is called beating and is done by shaking the vegetation or hitting it with a stick and holding a beating sheet underneath to catch the arthropods. The beating sheet is cloth and is held open and flat by crosspieces, like a kite. An open, inverted umbrella can also work as a beating sheet. Once the specimens are on the beating sheet they can be captured by hand, pooter, forceps or bag.
For soft vegetation like grasses, sweeping with a net is an effective collecting method.
For arthropods that scurry rapidly along the ground, setting out pitfall traps works well. A pitfall trap consists of a plastic cup that is set in a hole the collector digs in the ground so the lip of the cup is flush with the ground. The cup is then filled with the preserving fluid, and a raised roof put over the cup, to prevent vegetation from falling in. A marker flag is put by the trap so that it can be easily found when the scientists are ready to collect them at the end of their study in the area.
Leaf litter can be sifted and to attract nocturnal flying insects, a white sheet can be hung up with a bright light at the top of it. Collectors stand by the sheet and use their pooter, forceps or hands to catch insects that land on the sheet. For fast flying insects, collectors put up a malaise trap, which is a vertical, nearly invisible (to insects, at least) net that forces the speeding insects into a capture jar at the upper corner.
Once the specimens are captured by any of these methods, they are put in preserving liquids and labeled with all the necessary field data such as location (including geographic coordinates), elevation, habitat type, date, time of day, collector, and collection number.