Heath moth traps for monitoring moths

The MothNet Shedding Light on the Night and Ahi Pepe Mothnet projects involve the collection and identification of moth species. The project is a partnership between schools and Manaaki Whenua – Landcare Research scientists, Orokonui Ecosanctuary, Ngāi Tahu and the University of Otago and is funded by Unlocking Curious Minds, Biological Heritage National Science Challenge and Manaaki Whenua – Landcare Research. The aim is to find out about New Zealand’s native moths, where they are found and what their distributions can tell us about the country’s changing natural environment.

Ahi Pepe MothNet is a citizen science project designed to collect nationally significant information. The science team is using internationally recognised moth-monitoring techniques. They’ve established protocols, published local identification guides and developed the MothNetRecorder for data entry. This helps to ensure that students and their whānau collect robust, usable data. It also gives participants an insight into the world of science research.

If we all use the same type of trap, then all the data that anyone collects anywhere can all be brought together. That gives us our standardised quantitative data.

Dr Barbara Anderson

Students working with Ahi Pepe MothNet learn to use a variety of scientific equipment including Heath moth traps, Kestrel handheld weather stations, tracking tunnels and microscopes.

Heath moth traps

Heath moth traps use a fluorescent bulb that emits actinic light (whitish-blue light at the 420 nanometre range). Actinic light is attractive to moths but is not particularly bright for human vision – good for attracting moths but not keeping the neighbours awake at night! The fluorescent bulb is low wattage so it can run off a 12 V battery rather than requiring mains electricity. This, along with the ability to be flat packed, makes Heath moth traps easy to transport and use in remote locations.

The other components of the Heath moth trap are the fins, the funnel, the base and a solar unit. As moths fly towards the light, the fins deflect the moths down the funnel and into the base. The base has a few egg cartons in the bottom. Moths instinctively crawl into the shadows of the egg cartons and settle down. The solar unit switches the light bulb on at dusk and off at dawn.

The traps need to be checked early in the morning before the Sun heats up the trap and the moths become unsettled. The moths should be kept in a cool place or in the fridge until they can be observed.

Kestrel handheld weather stations

A Kestrel weather station sits above the Heath moth trap. It measures the altitude and the air temperature, humidity, air pressure, wind speed and wind direction every 10 minutes. The minimum, maximum and averages for temperature, humidity and wind speed are part of the environmental data collected at each monitoring site. This information helps the scientists better understand the environmental factors that determine the ecology of moths – what moths live where. The information also helps the scientists make predictions about how moths might be affected by climate change or habitat loss.

Tracking tunnels

Along with moth numbers, Ahi Pepe MothNet collects information on animals and invertebrates living in the area. Moths are an important part of local food webs, serving as food sources for native birds, reptiles and invertebrates. Tracking tunnels allow researchers to see what other creatures are out and about near the Heath moth trap. Four tracking tunnels circle each trap about 5 metres away from the light. Ahi Pepe MothNet is mainly interested in rodents, so the programme uses small tunnels baited with peanut butter. Predators also determine the ecology of moths.

Microscopes

Most moths caught in the Heath moth trap are counted and released if they are the same species. However, some moths are kept to make a local reference collection. Moths are quite small, so looking at them under a microscope enables the viewer to see the moths in greater detail. It’s often the small details that separate different moth species that are closely related.

Working as scientists

The scientific team from Manaaki Whenua – Landcare Research, the University of Otago and Orokonui Ecosanctuary are excited to offer students and whānau hands-on experiences using scientific equipment. Using citizen scientists to collect data is one way of gathering more information than one or two scientists could feasibly collect. It also introduces the public to scientific thinking and methodology. Possibly more importantly, it also strengthens and restores the connections students and whānau have with the environment around them.