BUGS 101: How to find bugs for dummies

By Johnathon Ridden and Morgane Merien of Canterbury Museum

In order to monitor the biodiversity around us, scientists use several methods to find bugs in the environment. Depending on what you are looking for, some are more suited for certain critters. Here is a quick 101 on what these methods are, and how to recreate them in your own backyard!

Light trapping
Light at night is a great attractant to a range of invertebrates, especially ones of the flying variety! You will know this if you leave a curtain open at night! There are many different types of lights that are attractive, but the most common one for insects is UV. A light trap turned on at dusk/night will draw nocturnal flying critters like moths or beetles. The light trap is usually set on a large white sheet, so it is clear to see and photograph all the insect visitors to document what is living in the surrounding area.

There are two light-trapping events planned for during the CNC:
1 Friday 26 April at Climate Action Campus
2 Saturday 27 April at Sullivan Park

Litter sieving
A litter sieve is a bag with two coarse mesh sieves. You place leaf litter and topsoil into the sieve and shake it up onto a white sheet. All the little things living at the soil surface are then exposed on the white sheet and can be photographed or collected into a pottle to look at under a microscope.

Pitfall traps
A pitfall trap is a container such as a cup with is buried in the ground, with the top of the container level with the ground surface. The idea is that any wandering crawling critter falls into the container if they come across the hole and are unable to crawl or fly back out of the cup. If it looks like it might rain, make a small ‘roof’ for your trap. Balance a small piece of wood or stone on four small stones (one for each corner). Leave room for bugs to slip in. You could also add small holes to the bottom of your pot to let water drain away. After a certain amount of time (it can be overnight or a few days), you can check your trap and empty the container into a tray to identify the critters you’ve caught.

Malaise trap
Malaise traps are tent-like contraptions which catch flying insects such as flies, wasps and butterflies. Named after its inventor – Swedish entomologist Rene Malaise, the tent structure has a large opening at the bottom in which insects fly up into and which leads them to collecting cylinder.

Sweep net
A sweeping net can be used to catch day flying insects such as bees, dragonflies, flies, wasps, and butterflies. You can swing the net back and forth through vegetation or use them to chase something that has caught your eye. After a series of sweeps, you can do a quick flick to trap anything you’ve caught into the bag of the net and check to see what it is.

Pure observation
The easiest way to find insects and spiders is through observation, being patient and taking your time to look through plants, flowers, soil, and the bark of trees. You can lift logs and stones and have a look at what might be hiding under there. You can also look for other clues which might give you an inkling as to the presence of small critters. These can be the frass (poo) left by certain insects, the eggs laid on leaves by insects such as shield bugs and butterflies. The webs of spiders are often a good indication that they are nearby. On plant leaves, you can look for feeding damage left by munching critters.

Publicerat 24 april 2024 07.22 av smankelow