The Mecoptera is an easily recognized order with a small extant fauna of 610 described species worldwide (Penny, 2006). North America is home to less than 100 species of Mecoptera, a fauna dominated in eastern North America by the conspicuously long-snouted and picture-winged common scorpionflies (Panorpidae). The other three families found in Ontario are the earwig scorpionflies (Meropeidae; one species), hanging scorpionflies or hangingflies (Bittacidae, three species), and snow scorpionflies (Boreidae; two species). Snow scorpionflies, now thought to be more closely related to fleas than to other Mecoptera (Whiting, 2002), are small, wingless, rarely encountered winter-active insects. The common scorpionflies and hangingflies, however, are conspicuous and common insects of eastern North American forests and many naturalists are familiar with their abundance, apparent morphological diversity, and interesting behaviour.
Identification of most Mecoptera is most easily and reliably accomplished by examination of the external male genitalia, which can be difficult to interpret on the basis of descriptions and line drawings. The colour photographs included here should be relatively easy to interpret, and to match to specimens in hand. Distributional data are given for Ontario only, but the keys will work for any eastern Canadian Mecoptera since all known eastern Canadian species occur in Ontario. The Mecoptera have a disjunct distribution in North America, with the eastern North American fauna separated from the relatively small western fauna. In Canada, several species of Boreus occur in British Columbia, Alberta and the Yukon, but Mecoptera are otherwise absent from Canada west of southeastern Manitoba. The keys herein will therefore work for any Canadian Mecoptera other than the western species of Boreidae (North American Boreidae are monographed by Penny, 1977). Ontario is the most Mecoptera-rich province, with 19 species compared with two species (Bittacus strigosus and Panorpa helena) in Manitoba, and 13 species known from Quebec (Aranguren, 1987). Mecoptera of the Maritime Provinces are inadequately known. We have restricted our Panorpa key to male specimens for the simple reason that males of this genus are easiest to identify. Good male specimens, with the genital bulb clearly visible, can usually be identified without special preparation although magnification of about 40X is recommended. Females are often only identifiable with dissection (the abdomen must be removed and cleared in potassium hydroxide), and the reader is referred to the keys in Webb et al. (1975) and Thornhill and Johnson (1974) for identification of females. Some females (such as P. nebulosa and P. acuta) are apparently indistinguishable morphologically.
The order Mecoptera has been the subject of a number of reviews and regional treatments over the past hundred years. Early treatments of the order include Hine’s 1898 and 1901 reviews of common scorpionflies and hangingflies, respectively, and Engelhardt’s 1915 treatment of the eastern North American fauna. Carpenter (1931) revised the Nearctic Mecoptera, but three of the Ontario species included here were described later in papers by Byers (1962, 1973). Several papers since then have dealt with regional scorpionfly faunas. The most important of these relative to Ontario Mecoptera are the reviews of the Illinois fauna by Webb et al. (1975) and the Michigan fauna by Thornhill and Johnson (1975). Both papers provide keys to species and deal with faunas similar to the Ontario fauna both in composition and size (18-20 species), and both use similar line drawings of male terminalia to support their keys. Webb et al. provide maps of the entire distributions of all scorpionfly species found in Illinois, only seven of which were shown as ranging into Ontario. Since the University of Guelph Insect Collection alone includes 17 species of Mecoptera, most of which are also present in Illinois, the Ontario fauna was obviously inadequately documented. The present work is based largely on the University of Guelph collection, supplemented with some records from the Canadian National Collection (Ottawa) and the Royal Ontario Museum (Toronto). Our objective is to document the Ontario fauna while at the same time providing more accessible and user-friendly keys than those available in published papers.
BIOLOGY AND BEHAVIOUR OF MECOPTERA:
Snow scorpionflies are wingless insects that feed on and develop in mosses, and are only active as adults during the colder months. Other Mecoptera are found from spring to fall, usually in shaded, organically rich, moist habitats, where they are often seen standing conspicuously on leaves (Panorpidae), or using their forelegs to hang from foliage of herbaceous plants (Bittacidae). When disturbed, many species will fly a short distance and come to rest on the foliage, but some drop to the ground when alarmed. Bittacidae are predators, often of small Diptera, and Panorpidae usually feed on dead or moribund insects, sometimes taken from spider webs (Thornhill, R. 1975, Jennings and Sferra, 2002). Both Bittacidae and Panorpidae have complex courtship behaviours involving alternative strategies and nuptial gifts of prey, dead insects, or salivary masses. Several papers deal with sexual selection and nuptial feeding behaviour in scorpionflies (Thornhill, 1976, 1992, Engqvist and Sauer 2001, 2003). Byers and Thornhill (1983) provide a more thorough review of the biology of Mecoptera.