Helping Moths and Butterflies

Moths and butterflies belong to insect order Lepidoptera, which means scaly wing in Greek. This order contains more than 350,000 known species worldwide. They are grouped into about 39 superfamilies depending on forms, behaviours and environment. Only 16 superfamilies are found in New Zealand. 35 out 120 families occur naturally in New Zealand, and only two families are butterflies.

Pieris rapae. Image fom Uykim LIM

The total number of native NZ species is not accurately known as many new species continue to be discovered. In addition, 68  species have been purposefully or accidently been introduced by humans. Those included cabbage white, Pieris rapae, known as white butterfly.

Moths are different from butterflies. It is easy to note that most butterflies have bright colors on their wings such as red, yellow or orange, and sometimes blue. Conversely, moths are usually a plain brown to dark-grey or white and often with masking patterns of zigzags.

Like other insects, both moths and butterflies have one pair of antennae. Antennae are used by insects to detect odours. In butterflies, antennae are long and thin, whereas in moths they usually short and thick with a great diversity of shapes, such as comb or feather-like. Body structure also allows us to distinguish between moths and butterflies. Moths tend to have hairy or fluffy bodies while butterflies have smoother abdomens.

Utetheisa lotrix. Image fom Uykim LIM.

Most moth caterpillars normally spin a cocoon made of silk in which they progress through a pupal stage such as silkworm, Bombyx mori. Most butterfly caterpillars, however, form an exoskeleton made from a hardened protein, often with a smooth and shiny surface like the Indian butterfly, Danaus chrysippus

Since moths and butterflies are associated with plants, they play several important ecological roles. Adult butterflies or moths lay their eggs on plants and feed, using a long, flexible ‘tongue’, from flowers. This action allows them to shake out sugar-rich nectar as well as to pollinate flowers.

In contrast, larvae browse on certain parts of plants, including leaves, seeds and flowers. The main job for caterpillars in their larvae stage is to eat. During several weeks in this life phase, they can consume up to 27,000 times their body weight.

Danaus chrysippus caterpillars feeding on milkweed. Image fom Uykim LIM.
Hornworm caterpillar on Sesame plant. Image fom Uykim LIM.

By this enormous amount of feeding, moth and butterfly’s larvae have been listed as one of the main insect pests on many crops. They influence a plant’s shape and impact a farmer’s economy. In order to control and maintain crop production, insecticides are often used. Although it is a first-class method for pest control, it always has its side effects. The application of chemicals don’t only kill crop pests but alaso kill off beneficial insects as well. To remedy this situation, many actions have been taken, including the restoration and conservation of forests, with the goal to retaining and attracting back Lepidopteran species.

In 2009, Brian Patrick and his colleagues studied Lepidoptera species present on Quail Island in Lyttelton Harbour. This island has been subject to a long term and successful vegetation restoration study. Almost 80,000 native trees and shrubs have been planted over the last two decades, making dramatic changes to the landscape and habitat.

The study aimed to identify native moths present on Quail Island and to compare the data to an earlier survey in 2003. The survey showed 146 species of Lepidoptera. Moreover, they found that 12 of 146 have been introduced to the island. The majority of the species were feeding on trees and shrubs, including the moths Pasiphila urticae, P. malachita and P. triphragma.

A view from Quail Island Image fom Uykim LIM.

As many moths depend on a specific larval host plant and a particular community, some interesting relationships were identified, including native brooms (Carmiichaelia) that support two uncommon moths: Zizina oxleyi and Pseudocoremia melinata. Many host plants can support more than two species of Lepidoptera. The number of moth species indicates that a large variety of trees, shrubs, and grassland have created a diverse habitat for the moths of Quail Island.

This study also concluded that the number of moth species had more than doubled compared to the survey done in 2003. The rise of moth species during these seven years is likely due to increased planting and the quality of plants on the island. Patrick also suggested that continuing to maintain diverse plants and introducing other new host plants is crucial to achieving a dynamic habitat as well as bringing back our native moths.

Uykim Lim is a postgraduate student in the Master of Pest Management at Lincoln University. Hewrote this article as part of his assessment for ECOL 608 Research Methods in Ecology.

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