"SHORT-HORNED" BUGS (Homoptera-Auchenorrhyncha)
K.G.A. Hamilton
STATUS
The diversity of "short-horned" bugs has been well sampled in Canada and the northern USA over the last half century, beginning with the Northern Insect Survey in the 1950s. Major collecting gaps include the boreal and montane areas of mainland British Columbia west of the Frazer River, northern Saskatchewan and the inland area of northern Québec. Bogs and understory plants in undisturbed woodlands are habitats that probably will yield additional bug fauna.
Fully 93% of the "short-horned" bug fauna in adjacent USA has been recorded from Canada. There are 12 families and 187 genera of these bugs represented in the Mixedwood Plains Ecozone (MWPE) of Ontario-Quebec. Our best estimate to date is 895 species, which probably represents 90-95% of the actual fauna. This is 56% of the entire fauna of these insects in Canada from an area representing less than 5% of Canada. The 4 largest families in the MWPE are leafhoppers (615 species), treehoppers (114 species), delphacid planthoppers (71 species) and spittlebugs (16 species). The remaining 9 families are represented by 78 species. Most families have 45%-60% of their Canadian fauna in the MWPE. This rises to 84% in treehoppers (which are best represented in deciduous forests). The mainly tropical fulgoroids Issidae and Flatidae have their only Canadian representatives - 4 species - in the MWPE.
Most "short-horned" bugs are well studied taxonomically but "micro-leafhoppers" (subfamily Typhlocybinae) are both poorly represented in collections, and require much systematic work. The treehopper genus Cyrtolobus also requires taxonomic revision (14 names here treated as species endemic to the MWPE may actually be colour forms of a single species).
The biology of these bugs is much less well known than their taxonomy. Probably at least half the species have imprecisely known distributions and dispersal rates; conclusions based on their distribution patterns (e.g. subdivision of the MWPE) are therefore tentative.
Food plants and ecological zonation patterns are best studied for tree-and grass-feeding bugs. Tree-inhabiting species, especially "micro-leafhoppers", probably are dispersed by wind much more than ground-inhabiting species. An extensive fauna is associated with understory vegetation in woodlands, but knowledge of this component remains fragmentary.
For biogeographical analysis, I exclude 1 unconfirmed record, 82 species only presumed to occur in the MWPE, and 215 wind-carried native "micro-leafhoppers" thus reducing the well-studied component of the fauna to 611 species.