What comes to light at night – Mothing at UPDC

While many people are fascinated by butterflies, only a few pay much attention to moths - and quite unfairly so.

There are around 160,000 described species of Lepidoptera (butterflies and moths) worldwide and the majority of them are nocturnal in their adult stage. As many moths are important pollinators of wild and domesticated plants, they also play an important role in a lot of different ecosystems. Monitoring them at sites with varying levels of disturbance can be very helpful in gaining a better understanding of the impact of anthropogenic influences.

For my master's project, I was comparing the diversity of two habitat types. First, well-established secondary forest and second plantations of banana and balsa trees. I used simple light traps, consisting of a white bedsheet with a light bulb and UV light placed in front of it. The first setup was located behind the station house, while the second was placed at a local neighbour's farm, surrounded by the plantations. See some of our night and day time observers in the pictures below.

The Sphingidae - Hawk Moths

In particular, I focused on the diversity within two families. First, the Sphingidae, commonly known as hawk moths. They are famous for their fast, agile flight and their ability to hover in front of flowers like hummingbirds. As many species feed on nectar, they are important pollinators and have evolved alongside certain plant species. 

The pictures show Xylophanes mirabilis, a beautiful deep-green moth with a red underside and a specimen of Pachylia darceta on the right.

The Saturniidae - Giant Silk Moths

The second family I looked at was the Saturniidae, commonly known as giant silk moths. As the name suggests, some of them can be very large. Generally, they can vary a lot in their morphology, with some groups also being quite small. Many species have big, vertebrate-like eyespots on their hind wings, helping them to frighten off predators. As herbivorous larvae and an important food source for many other animals, they play a valuable role in certain ecosystems. The mouthparts of most species are stunted. Because of that, they usually don't eat as adults and use the energy reserves from their larval stage. The adult stage is therefore very short and serves mainly for mate finding and reproduction.

In the left picture is an example of Automeris cf. banus, revealing one of its eyespots. The right one shows some big genera of Saturniidae, like Eacles sp., Rhescyntis sp. and Rothschildia sp.

Species Identification

To identify the species, I took pictures and compared them with photos and descriptions of different books, field guides, citizen science platforms and other online resources. Dissection of mouthparts or genitals is also a common method for identifying moths, especially if no DNA barcoding is used. However, there are often significant limitations. Due to the large number of species, information on some is limited, and in many cases, it is almost impossible to find any detailed descriptions. Therefore, further research is essential to improve our understanding of moth diversity, particularly in tropical regions.

A Rare Encounter

Last but not least, here is a picture of a rare encounter with a giant moth measuring 26 cm in length. Thysania agripina, aka White Witch, is probably the Lepidoptera with the largest wingspan. Individuals with a length of around 30 cm have been recorded, which gets them on the list of the biggest insects in the world. Even though this is a species from the family Erebidae, it shows that every night at the moth sheet can bring an unexpected discovery.