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 Immature stages are generally very poorly understood, and descriptions and identification keys are mostly lacking, unpublished or are scattered throughout the available literature.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:
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.
Families not included in the key
Single species, recently described Australian, basal family (in Glossata).
Small Neotropical family, 6 species, formerly in Megalopygidae.
Consists of one genus Andesiana with three species.
17 genera and about 250 species.
1 genus, 157 species, in the Yponomeutoidea.
1 genus, 52 species in the Yponomeutoidea.
Small family in the Depressariidae assemblage of the Gelechioidea.
Small family of 7 genera with 100 species in the Scythrididae assemblage of the Gelechioidea.
Monogeneric cosmopolitan group of 16 species (Yponomeutoidea).
9 genera (Bombycoidea).
Small family in the Tineoidea. In Australia the larvae are well-known for making the ‘scribbles’ in scribbly gums.
Old World tropics, Australasia, Madagascar.
8 genera in the Calliduloidea.
Southern Africa, South America and New Zealand
Nine species in Incurvaroidea.
Small family In the Cimelioidea.
South-western United States, Mexico and neighbouring areas
6 species, in the Drepanoidea.
Old World from Africa and Madagascar to Australia and New Guinea.
Monogeneric, with 6 species.
Himalayas, Japan, Korea.
10 genera, in the Geometroidea.
8 genera, 212 species in the Tineoidea.
Worldwide distribution including Australia
29 genera, 520 species, in the Noctuoidea, little data available on larvae.
Mediterranean region and Africa
2 genera in the Zygaenoidea.
Africa and tropical Asia
11 genera, 80 species, in the Zygaenoidea.
Australian, Oriental and Afrotropical regions and in Central and South America
8 genera, 120 species, in the Zygaenoidea.
6 species in one genus.
Mainly Oriental and Afrotropical
18 genera, 196 species, in the Cossoidea.
Nearctic and Palaearctic
3 genera and 4 species, In the Choreutoidea.
Single genus, Mnesarchaea.
South America and southeast Asia
13 species in 4 genera.
8 species, in the Noctuoidea.
South America, Australia, Africa.
7 genera, 57 species.
Nearctic, Neotropical, and Oriental Regions
7 genera, 28 species
3 genera, 15 species, in the Zygaenoidea.
4 genera, 25 species, in the Bombycoidea.
3 genera, 47 species, in the Yponomeutoidea.
1 genus, 1 species.
Mediterranean and South Africa
11 species, in the Scythrididae assemblage of the Gelechioidea.
3 genera, 10 species, in the Cossoidea.
Palaearctic, Oriental and Australian
13 genera and 53 species, in the Gracillarioidea.
Holarctic and Neotropical
2 genera, 8 species.
Neotropics and South Africa
41 species in the Geometroidea.
Australia, China and India
2 genera, 4 species.
Palaearctic and Afrotropical
4 genera, 8 species, in the Zygaenoidea.
Europe, Nearctic and Neotropics
3 genera, 66 species.
1 genus, 2 species.
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