BUTTERFLIES AND MOTHS
(Lepidoptera)
J.D. Lafontaine
LEPIDOPTERA CLASSIFICATION AND HABITS
The terms "butterfly" and "moth" are often thought of as the two natural groups that make up the order Lepidoptera but in reality the butterflies are only one of many Lepidoptera lineages; butterflies are more closely related to the larger moths than either group is to the more primitive families of moths. The butterflies and the larger moths are often associated in a group called the "macrolepidoptera." The families of smaller moths are referred to as "microlepidoptera." While the macrolepidoptera may represent a natural group, the microlepidoptera is more a grouping of convenience that lumps together many different families of small sized, primitive moths. For convenience of discussion, I have arranged the 63 families of Lepidoptera into four groupings that represent different habits and different levels of knowledge.
The first group is the leaf-mining microlepidoptera. This group of 33 families are mostly small moths, frequently with narrow wings like those of a mosquito (wing expanses of 5-15 mm are typical), usually with a wide hairlike fringe. The larvae most commonly bore in plant tissue, including seeds, stems, roots, bark and leaves. This group includes a number of pests, both of living plants and of stored products, clothes, and carpets. The majority of species are called leaf miners because the larvae feeds on the chlorophyll between the upper and lower leaf surfaces; this results in a characteristic clear patch in the leaf where the green chlorophyll has been removed. Many species can be identified in the larval stage by considering both the shape and position of the mine on the host plant and the identity of the host. Unfortunately this information has been published for few species. Many species are host specific. The leaf mining microlepidoptera are generally rarely collected and poorly known; although the Ottawa area is one of the best known areas for this group in North America. A total of 522 species of GROUP I microlepidoptera are known from the Mixedwood Plains Ecozone of which 81% (423/522) are known from the Ottawa region. This high percentage results from the relatively intensive collections that have been made in Ottawa compared with other areas. We expect that the actual number of species in the Ecozone will eventually reach about 1000. Most species in this group are known only from a few widely scattered locations so it is not usually possible to determine the limits of distributions or recognize endangered species except by association with endangered habitats or plants. For example, the gelechiid moth Anacampsis lupinella is known in Canada only from the lupine patch near Toronto that formerly supported a colony of the Karner Blue. The three butterflies associated with lupine, Persius Skipper, Frosted Elfin and Karner Blue, are probably extinct in Ontario but the fate of the gelechiid is unknown; it has not been collected in Ontario since 1900.
The second group is the leaf-rolling and stem-boring microlepidoptera (GROUP II). The adults are generally larger than leaf-miners (wing expanses of 15-30 mm are typical) and the wings are more triangular in shape with only a narrow fringe. The larvae most commonly roll or fold a leaf and tie it with silk, or tie several leaves together, and feed in the protected enclosure. This group includes agricultural pests (e.g. European Corn Borer, Ostrinia nubilalis), forest pests (e.g. Spruce Budworm, Choristoneura fumiferana) (Fig. LEP-1), and household pests (e.g. Indian- Meal Moth, Plodia interpunctella). This group contains 782 species in 12 families in the Mixedwood Plains Ecozone of which two families, Tortricidae and Pyralidae make up 85% of the fauna (Fig. LEP-2). This group is better collected and better known than the leaf-mining microlepidoptera and probably more than 80% of the fauna of the Ecozone is known. Once again, collections from the Ottawa area contain 80% of the entire fauna of the Ecozone (618/782) suggesting that future collecting in southern Ontario and Quebec will add about 200 species to the fauna of the Ecozone. This would result in a proportion of about 65% of the fauna of the Ecozone occurring in the Ottawa area, as is the case in butterflies, and is probably a more realistic proportion.
The third group of Lepidoptera is the macrolepidoptera (GROUP III) which contains the larger moths. Included here are 1155 species in 13 families of which the geometers or inch-worms (Geometridae) and cutworms (Noctuidae) make up 82% of the Group III fauna. In fact the cutworms (family Noctuidae), with 692 known species in the Ecozone, make up more than 27% of the entire Lepidoptera fauna. As in the two groups of microlepidoptera, 81% of the fauna of the Ecozone is known from the Ottawa area suggesting that several hundred species remain to be discovered in the southern part of the Ecozone. The larvae usually are exposed when feeding but are usually protected by spines (Saturniidae), tufts of hair (Arctiidae, Lymantriidae, Lasiocampidae, some Noctuidae), or cryptic coloration (Geometridae, Drepanidae, Notodontidae, most Noctuidae). Many noctuid larvae hide during the day in the soil and leaf litter and come out at night to feed. This group includes our largest Lepidoptera with the Cecropia Moth (Hyalophora cecropia) (Fig. LEP-3) having a wingspan up to 15 cm and the Polyphemus Moth (Antheraea polyphemus) having one up to 13 cm. Typical wingspans of most macrolepidoptera are between 25 and 40 mm although some species may be as small as 12 mm (e.g. Noctuidae: Hypenodes). This group contains some very familiar pests such as Tent Caterpillars (Lasiocampidae: Malacosoma) (Fig. LEP-4), Tomato Hornworm (Sphingidae: Manduca quinquemaculata), Gypsy Moth (Lymantriidae: Lymantria dispar) (Fig. LEP-5), Armyworm (Noctuidae: Pseudaletia unipuncta), Corn Earworm (Noctuidae: Helicoverpa zea), and Fall Cankerworm (Geometridae: Alsophila pometaria). Unfortunately, only a few groups of macrolepidoptera are popular with amateur collectors so distributional information on most families remains rather spotty. Popular groups are the Sphinx, or Hawk Moth family (Sphingidae) (Fig. LEP-6) (Fig. LEP-7), the Giant Silk Moths (Saturniidae), Tiger Moths (Arctiidae), and a group of cutworm moths called Underwing Moths (Noctuidae: genus Catocala).
The fourth group, a subset of the macrolepidoptera, is the butterflies. Five families of butterflies occur in the Mixedwood Plains Ecozone and 144 species. The combination of colorful patterns, diurnal flight, and abundance of identification aids, has made butterflies the most popular insect group with amateur entomologists. As a result, the distribution of the butterflies in eastern Canada in general and the Mixedwood Plains Ecozone in particular is very well known so it is these patterns that form the primary basis for the analysis of distribution patterns given below. As in the macrolepidoptera, most butterfly larvae feed exposed and rely on cryptic coloration, warning coloration, or spines for protection. The majority of butterfly larvae are covered with a dense layer of short hair that gives them a fuzzy appearance (e.g. Lycaenidae, Hesperiidae, Pieridae, and some Nymphalidae) or are armed with impressive branching spines (e.g. most Nymphalidae). Others, such as the Monarch (Danaus plexippus) and some of the Swallowtails (Papilionidae) are toxic to predators and have a warning coloration. Many butterflies are powerful fliers and some are strongly migratory so that 21% (30/144) of the butterfly fauna of the Ecozone are vagrant species that do not live permanently in the area.
Table 1 lists the 63 families of Lepidoptera known from the Ecozone in the four groups described above. The number of species known from the Ottawa region is given for each family as a base line because this area is so well known compared to other parts of the Ecozone. For comparison, the total number of species known from the Ecozone, and the number from North America north of Mexico is also listed. The latter number is from Hodges et al. (1983).