Tamalia (Hemiptera: Aphididae: Tamaliinae), a Nearctic aphid genus, is associated with galls on woody plants in the family Ericaceae (Arctostaphylos spp., Arbutus arizonica, and Comarostaphylis diversifolia). Tamalia cruzensis Miller and Pike, n. sp., Tamalia glaucensis Miller and Pike, n. sp., and Tamalia moranae Miller and Pike, n. sp. are described and illustrated. Two of these, T. cruzensis and T. moranae, represent host plant records for Tamalia on genera other than Arctostaphylos spp. Character measurements, comparisons, and descriptions; DNA cytochrome oxidase subunit 1 sequences; geographic distributions; seasonal occurrence; biology; and host plant associations are provided, along with diagnoses and a key to the known species based on the gall-inhabiting apterous adult stage.

Melaphis rhois Fitch (Hemiptera: Aphididae) has been considered the only North American representative of the aphid subtribe Melaphidina. Molecular and morphometric analysis indicates that there are at least three sympatric cryptic melaphidine species in North America. Melaphis asafitchinew species is described and M. rhois is redefined and a neotype designated. The name Melaphis minuta Baker cannot be assigned to either of these species. Details of the life cycles of Melaphis Walsh species, including the existence of ovoviviparity in sexual females, is discussed.

Little is known about the associations of ants (Hymenoptera: Formicidae) with subterranean aphids and mealybugs (Hemiptera: Sternorrhyncha: Aphididae and Pseudococcidae), particularly in Canadian grasslands. Knowledge of host plants for these sternorrhynchans is equally rare. We carried out a plant-based survey of ants and belowground aphids and mealybugs in a native fescue grassland in east-central Alberta, Canada. We found 23 species of ants, 12 of which (species of Lasius F., Myrmica Latreille, Tapinoma Förster, and Temnothorax Mayr) were in association with subterranean sternorrhynchans. Twelve species of aphids and mealybugs were collected; 3 are new records for Canada and 2 are possibly undescribed. Most ant species associated with sternorrhynchans were found with more than one species of sternorrhynchan, sometimes in the same nest. Almost all sternorrhynchans were found on graminoid hosts (Poaceae and Cyperaceae); there was little observed plant-specificity beyond this. There were no significant correlations between presence of subterranean sternorrhynchans and percent cover of different plant types, soil moisture content, slope, aspect, or visible entrances to ant nests.

Apterous adult morphs of eriosomatine aphids associated with moss (Bryophyta) and/or roots of conifer (Pinaceae) or willow (Salix Linnaeus (Salicaceae)) in forests of the North American Pacific Northwest including Alaska are described, illustrated, and keyed. In total, seven species (Clydesmithia canadensis Danielsson, Melaphis rhois (Fitch) (moss only feeder), Pachypappa rosettei (Maxson), Pachypappa sacculi (Gillette), Prociphilus americanus (Walker) (fir root only feeder), Prociphilus xylostei (De Geer), and Thecabius populimonilis (Riley)) are characterised from their secondary host habitats. Secondary host forms of C. canadensis and T. populimonilis are described for the first time. The morphotypes from the secondary hosts were confirmed through deoxyribonucleic acid sequence matching with those from the primary hosts.

A molecular and biometric assessment and redescription of Myzodium mimulicola (Drews and Sampson) are provided. New North American host and distributional data are presented, including the first record from Alaska. Myzodium knowltoni (Smith and Robinson) is a junior subjective synonym of M. mimulicola, based on molecular-sequence and morphological evidence. A key to the known Myzodium species (apterae and alatae) is included.

Morphometric techniques, DNA mitochondrial cytochrome c oxidase subunit 1 gene (COI) barcoding, and microsatellite flanking region sequences were used to assess the reliability of suggested morphological characters in distinguishing the green apple aphid (Aphis pomi De Geer) from the spirea aphid (Aphis spiraecola Patch), and to assess variation within these species. Both molecular approaches clearly distinguished two groups corresponding to the morphologically defined species. Differences in the length of the distal rostral segment and the number of lateral tubercles were found to be robust indicators of species membership, performing as well as multivariate approaches. Among A. pomi samples, microsatellite flanking region sequences were relatively uniform, whereas A. spiraecola exhibited much variability, which suggests that North American populations of the latter species are genetically much more complex.

Species of Braggia Gillette and Palmer (Hemiptera: Aphididae: Aphidinae: Aphidini) feed on various buckwheat, Eriogonum Michx. (Polygonaceae), species in western North America. Two new species, Braggia columbiana Pike n. sp. from Washington and Oregon and Braggia longicauda Pike n. sp. from Washington, Oregon, and northern California, are proposed. Descriptions, diagnoses, illustrations, mitochondrial cytochrome c oxidase subunit 1 “barcode” sequences, a key to the species of Braggia, and notes on biology, distribution, and parasitoid associations are provided.