Introduction

Lepidoptera (moths and butterflies) are one of the largest orders of animals in the world with over 180,000 named species (10% of named organisms), and at least one-third that number again yet to be described. They are a ubiquitous group and are one of the most easily-recognised insects. They are also one of the four mega-diverse groups of what are considered to be the most evolutionarily ‘advanced’ insect orders. The others are the beetles (Coleoptera), the flies (Dipterans), and the bees, wasps and ants (Hymenoptera).

Moths and butterflies have a strong relationship with plants. The great majority of the larvae (caterpillars) are herbivores and many adults ingest nectar, often acting as pollinators. Most species are associated with only one or a few species of related plants. However there are many that are polyphagous, eating various unrelated plant species. Consequently, Lepidoptera are often of economic concern, and this brings them into conflict with humans as competitors for major food sources. Many moths and butterflies are also very strong fliers, enhancing their ability for long distance dispersal, and pest species are often also readily transported around the world via human activity.

There is much more accessible information about adults of insect species than larvae. Immature stages are generally very poorly understood, and descriptions and identification keys are mostly lacking, unpublished or are scattered throughout the available literature. Identification keys are tools that allow us to identify species or groups of organisms based on morphological characteristics. However, they can always only hope to generalise about groups of taxa on what little knowledge we have compiled over many years with exceptions in most taxonomic groups.

The objective of this Lucid Key is to provide a tool for the identification of caterpillars to family level, with a particular focus on families of biosecurity concern to northern Australia. We have included as many families of Lepidoptera as possible, to make the key broadly applicable to most caterpillars encountered in Australia, either as border interceptions or collected (or just observed) by the public, within the limitations of the key (see How to Use). Not all 129 extant families of Lepidoptera (van Nieukerken et al. 2011) could be included in this key; 45 have been excluded and are listed in Table 1. These are mostly families of which little or nothing is known about immature stages and are generally small and geographically limited. Most, by far, are unlikely to be encountered in Australia. However, in future, some of these missing families will be added to the key as data on larvae become available.

Any identification tool relies on a stable taxonomy. We have made every effort in this key to use the most up-to-date taxonomy, but this will be continually revised as changes are made to Lepidoptera systematics. This key will be updated regularly with more information as it comes to hand. Modernised and accurate taxonomy greatly assists the ability to generalise the characteristic features of groups. Major sources of information used in this key on most Lepidopteran families include the following:

• Kristensen, NP (ed.), Handbook of Zoology. 4(35.1). De Gruyter, Berlin, New York. 1999
• Stehr FW, PJ Martinat, DR Davis, DL Wagner, JB Heppner, ME Brown, ME Toliver, JY Miller, JC Downey, DJ Harvey, N McFarland, HH Neunzig, GL Godfrey, DH Habeck, JE Appleby, M Jeffords, JP Donahue, JW Brown & DC Frack (1987) Order Lepidoptera, pp 288–596. In Stehr, FW (ed.), Immature Insects. Kendall/Hunt, Dubuque.
• Common, IFB (1990). Moths of Australia. Melbourne University Press, Collingwood, Victoria.

Numerous other sources for specific taxa were also referenced and these are listed in individual Fact Sheets for selected families.

Table 1. List of 46 lepidopteran families not yet included in The Caterpillar Key. Most of these families have been excluded because little or nothing is known about their immature stages and they are generally small and geographically limited. Most are unlikely to be encountered in Australia.

Reference

van Nieukerken, EJ, L Kaila, IJ Kitching, NP Kristensen, DC Lees, J Minet (2011) Order Lepidoptera Linnaeus, 1758. In: Zhang, Z-Q (ed.), Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa 3148: 212-221