The Nearctic Region genera of Phoridae are revised, and it is shown that the current classification into three subfamilies is inadequate. The hypothesis that the most closely related taxa to the Phoridae are the Sciadoceridae and Ironomyiidae is supported. Use of these outgroups to polarize character states in the Phoridae allows the reorganization of this family into five subfamilies: Hypocerinae, Phorinae, Aenigmatiinae, Conicerinae, and Metopininae. The newly re-defined Phorinae is the adelphotaxon (sister-group) of the Aenigmatiinae + Conicerinae + Metopininae, among which the relationships are unresolved. The hypocerines are the adelphotaxon of all other extant Phoridae. Within the Hypocerinae the relationships of the 15 included world genera are hypothesized, and three new genera are proposed. The relationships of the eight world phorine genera are only partly resolved. The Aenigmatiinae is organized into two tribes: Aenigmatiini and Diplonevrini. The relationships of the seven world genera of Diplonevrini are hypothesized, whereas those of the Aenigmatiini are not discussed. The six world conicerine genera are revised and their relationships hypothesized. In the Metopininae, two major groups are recognized, the Metopina-group and the Megaselia-group. Beckerina Malloch is the adelphotaxon of these two groups, whereas Rhopica Schmitz and Triphleba Rondani are successive outgroups of all metopinines. The Metopina-group is mostly tropical in distribution and is not discussed further. The Megaselia-group is partially organized into the Gymnophora-subgroup and the Apocephalus-subgroup. Species-level revisions of genera are needed before further progress can be made in this family, because the distribution of character states is insufficiently known. Genera in great need of revision include Peromitra Enderlein, Chaetopleurophora Schmitz, Megaselia Rondani, and Apocephalus Coquillett.

The success of microbial control programmes often depends on an adequate mass-production method for the agent used. The pathogens with potential for use against grasshoppers and locusts vary widely in the ease with which they can be mass-produced. Obligate pathogens such as grasshopper entomopoxviruses, mermithid nematodes and Nosema locustae Canning are currently restricted to culture in living systems. Liquid fermentation is usually employed for the production of non-obligate pathogens such as bacteria, some fungi and nematodes, but in some cases the propagules produced in liquid culture are not amenable to formulation and application. Conidia of hyphomycete fungi can be produced on the surface of liquid media, on solid substrates or in diphasic systems. Production on solid substrates has been adopted for production of steinernematid and heterorhabditid nematodes and some fungi. Diphasic liquid-solid fermentation combines the benefits of both systems and is used mostly for mass-production of hyphomycete fungi such as Metarhizium flavoviride Gams & Rozsypal and Beauveria bassiana (Balsamo) Vuillemin. Increased commercial interest in biological control is likely to accelerate the development of improved and more economical methods for the mass-production of microbial control agents.

The biology, ecology, disease etiology, and biological control potential of different members of the Entomophaga grylli species complex are discussed. This complex is represented by several pathotypes that include members that produce both conidia and resting spores within a single season, and members that produce only resting spores. This complex is known as a major pathogen of acridids from most areas of the world where populations of these insects are found, including Africa, Asia, Australia, Europe, North America, and South America. Pathogens from this species complex commonly cause disease epizootics in their host populations and are known to reduce significantly outbreaks of grasshoppers, particularly following periods of rain or high humidity. Specific factors that either limit or enhance disease processes and host mortality are discussed in relation to both epizootiology and biological control programmes. Recent biological control efforts are discussed and the potential of using members of the E. grylli species complex in both augmentation and introduction programmes is considered.

The use of chemical insecticides, especially as ultra low volume (ULV) formulations, against locusts and grasshoppers will continue for the foreseeable future; therefore application techniques for microbial agents should be as compatible as possible with existing practice. Low volume and ULV spraying of deuteromycete conidia in oil-based formulations have produced very promising acridid control results in the field, although baiting, dusting, and hydraulic application techniques have also been tested for a wide range of pathogens.The key problems for further research and development appear to be the logistics and supply of consistently reliable formulations for application on a large scale, and the determination of mechanisms for effective dose transfer in the field. The application of suspended particulate matter can present special problems with rotary and other atomizers.

A group of tarsonemid mites, which are egg parasites of ipine bark beetles, is reviewed on a Holarctic basis. The genus Iponemus (new name for Moseria Beer and Nucifora) is proposed and described for the group, and 24 species or subspecies, including 19 described as new, are described, keyed, and illustrated. A detailed species-group description follows the generic description, and includes several structures hitherto not reported for species of Tarsonemidae. The variation and usefulness of the few characters available for distinguishing forms of Iponemus is discussed, and the provisional treatment of some forms as species and others as subspecies is explained.These mites are among the most host-specific associates of scolytid beetles: 16 of the 18 species or subspecies of Iponemus associated with the nearctic, pine-feeding ipines are monospecific, and each of the other two is restricted to two closely related species of hosts. The mites and the beetles together are considered with regard to size correlations, the degree of host specificity, the mites as taxonomic indicators of their hosts, biogeography, life history, and the role of egg parasitism by the mites in the population regulation of their hosts.

The taxonomy of the Nearctic genus Ophraella Wilcox is revised. Data for all known immature stages are included. Ophraella integra (LeConte) is synonymized with O. notulata (Fabricius). Ophraella dilatipennis (Jacoby) is transferred to the genus Neolochmaea Laboissière.Thirteen species are recognized, of which 6 are new : O. arctica, californiana, communa, macrovittata, nuda, and pilosa. The distribution and host plants of species are as follows : O. americana, eastern North America, on Solidago spp.; O. pilosa, transcontinental along the Canadian border, on Aster, primarily A. macrophyllus; O. cribrata, coast to coast in the United States, on Solidago of the subgenus Virgaurea; O. conferta in northeastern states, on Solidago with preference for S. canadensis and S. rugosa; O. sexvittata in southeastern states, on Solidago spp.; O. notulata in eastern US and Gulf states to Mexico, on Iva oraria; O. notata in eastern portion of the United States, on Eupatorium perfoliatum; O. macrovittata in the Gulf states, host plant unknown; O. communa in North America and Mexico, on Ambrosia artemisiifolia; O. bilineata in the Canadian Prairies and the bordering states, on Chrysopsis villosa; O. californiana in California and Mexico, on Artemisia Douglasiana; O. nuda in Alberta, host plant unknown; and O. arctica in tundra zone, on Solidago multiradiata scopulorum.The life cycles of most species are still unknown but most species probably have only 1 generation per year. The eggs are laid in clusters on the under surface of young leaves. The larvae skeletonize young leaves and live exposed. Before pupation, the larva spins a loose cocoon and attaches it to a leaf tip. Pupation lasts 1–2 weeks. The newly hatched adults are active on host plants until the early fall, when they enter the leaf litter for overwintering.

Three subfamilies are classified in Eupelmidae: Calosotinae Bouček, Eupelminae Walker, and Metapelmatinae Bouček. Diagnoses of these three subfamilies and of Tanaostigmatidae are given, together with a key to distinguish members from each other and from other Chalcidoidea. Genera of Calosotinae and Metapelmatinae are revised for the world, with a key to genera given for both subfamilies. For each genus the following is provided: synonymy, description of structural features of males and females, notes on distribution and hosts, available keys to species listed by biogeographic region, and a catalog of species. New generic combinations are made in the catalogs of species based on examination of type specimens of the species. Eight genera are included in Calosotinae [type species in brackets]: Archaeopelma gen.nov. [A. tropeotergum sp.nov.], Licrooides gen.nov. [L. umbilicatus sp.nov.], Paraeusandalum gen.nov. [P. chilense sp.nov.], Eusandalum Ratzeburg, Chirolophus Haliday, Calosota Curtis, Balcha Walker, and Tanythorax gen.nov. [T. spinosus sp.nov.]. Four genera are included in Metapelmatinae: Metapelma Westwood, Neanastatus Girault, Eopelma gen.nov. [E. mystax sp.nov.], and Lambdobregma gen.nov. [L. schwarzii (Ashmead) comb.nov.]. The following are proposed as new synonymies: Notosandalum De Santis and Exosandalum Bouček = Eusandalum Ratzeburg, and Metacalosoter Masi = Calosota Curtis. Eighteen structural features of adults of the three eupelmid subfamilies, and of other Chalcidoidea including Tanaostigmatidae, Encyrtidae, Aphelinidae, and Pteromalidae, are studied to delimit character states and determine their distribution among the higher taxa. Twenty-two additional features of adults of Calosotinae and Metapelmatinae are studied for supplemental evidence of relationships among the genera in these two subfamilies. Observed character-state distributions are used to postulate character polarity and homoplastic states, and hypotheses of monophyly and relationships among taxa are based on proposed synapomorphic states. Aphelinidae sensu lato (including the subfamily Eriaporinae) are indicated as either a paraphyletic or polyphyletic taxon if the Eriaporinae are included but the Signiphoridae are excluded. Tanaostigmatidae sensu lato (including the genus Cynipencyrtus Ishii) are indicated as the sister group of Encyrtidae based on a relatively long mesoscutal process for the muscle pl2–t2c, and structure of the articulation between the mesoscutum and scutellar-axillar complex. The genus Cynipencyrtus Ishii is indicated to be most closely related to Encyrtidae based on common possession of transverse axillae and mesotibial apical pegs. Possible relationships among Calosotinae, Metapelmatinae, and Eupelminae, and among these and Tanaostigmatidae + Encyrtidae remain unresolved. There are no derived character states unique to either Eupelmidae, or Eupelmidae + (Tanaostigmatidae + Encyrtidae), so that these taxa and relationships are not definitively supported as monophyletic. Eupelmidae may represent a grade-level taxon with membership determined by similar suites of apomorphic states that function to enhance jumping ability. Cladograms are used to illustrate alternate hypotheses of character-state evolution and relationships among the genera of Calosotinae and Metapelmatinae. Distribution of character states for the higher taxa and for each genus of Calosotinae and Metapelmatinae is summarized in two tables. Scanning electron photomicrographs are used to illustrate structural features.

Ecosystems that are managed for resource production are under continual structural change. Changes imposed by local management aggregate to produce regional patterns and new regionwide responses. Anthropogenic influences on hemispheric and global processes add another level of change. The result is a bewildering variety of real or anticipated changes unique to experience. For example, in the spruce/fir and budworm interaction of eastern North America, a syndrome of causes affects the vulnerability of renewable resources, and the triggers of change can never be predicted. Yet, it is possible to identify key features that affect resilience of ecosystems and robustness of regulation and to reject other possibilities. This approach provides a way to assign priorities for research and for contingency planning to adapt to change.

Fossils from sites of Late Quaternary age in North America provide tangible evidence of temporal changes in the character of the northern beetle fauna. Based on a synthesis of the fossil data with analyses of the present distributions for northern species, a rudimentary model is proposed to explain the recent history of the fauna of the arctic and the boreal forest.An open-ground beetle fauna of arctic–subarctic affinities had become established along the southern margin of the Laurentide ice sheet in the midcontinent by 20 500 years before present (yr B.P.). Climatic warming decimated this fauna throughout lowland areas at some time between 16 700 and 15 300 yr B.P.; small populations of some arctic–subarctic species, however, survived within either alpine habitats of the Cordillera and Appalachians or specialized environments associated with stagnant ice.Populations of the same arctic–subarctic beetle species existed within the ice-free Alaska–Yukon refugium throughout the late Wisconsinan. During the Holocene, this region served as the principal centre-of-origin for the dispersal of the arctic–subarctic beetle fauna.The beetle fauna of the boreal forest was also displaced southward by Late Wisconsinan glaciation. By 15 300 yr B.P., however, this fauna had largely replaced the arctic–subarctic beetle fauna along the ice margin of the midcontinent. Evidence provided by fossils from a series of sites demonstrates that beetle species of the boreal forest dispersed northward into Canada as the ice front receded.

The genus Lygus Hahn is revised for North America. The new synonyms (to the left of the equal sign) are: ceanothi var. deliticus Knight = humeralis Knight; convexicollis var. coloratus Knight and dolichorhynchus Stanger = convexicollis Reuter; nigritus Knight = ravus Stanger; brindleyi and fultoni Knight = robustus (Uhler); superiorensis Knight = columbiensis Knight; frisoni Knight = rubroclarus Knight; nigrosignatus Knight = elisus Van Duzee; ultranubilus Knight and epelys Hussey = nubilus Van Duzee; and nubilosus Knight and usingeri Stanger = nubilatus Knight. The 34 species known to occur in North America are: abroniae Van Duzee, aeratus Knight, atriflavus Knight, atritibialis Knight, borealis (Kelton), bradleyi Knight, ceanothi Knight, columbiensis Knight, convexicollis Reuter, desertinus Knight, elisus Van Duzee, hesperus Knight, humeralis Knight, lineolaris (Palisot de Beauvois), mexicanus Kelton, nigropallidus Knight, nubilatus Knight, nubilus Van Duzee, oregonae Knight, perplexus Stanger, plagiatus (Uhler), potentillae Kelton, ravus Stanger, robustus (Uhler), rolfsi Knight, rubroclarus Knight, rubrosignatus Knight, rufidorsus (Kelton), shulli Knight, solidaginis (Kelton), striatus Knight, unctuosus (Kelton), vanduzeei Knight, and varius Knight.Species are redescribed, seasonal variations in size and colour are discussed, and distribution maps and host plants are included. The adult males are illustrated and a key for their identification is given.

The species of the genus Tachinus (Staphylinidae: Tachyporinae) of North and Central America are revised. Forty-four species are recognized, of which eight are described as new; eight species names are placed in synonymy. The subgenera Drymoporus Thomson and Porodrymus Rey are placed in synonymy with Tachinus and the genus is divided into 17 species groups based on an examination of both the Nearctic and the Palearctic fauna. The distribution of each species is mapped and the male genitalia, the male and female eighth abdominal sternites and tergites, and the male seventh sternite are illustrated for every species. A neotype is designated for T. fumipennis Say, and lectotypes are designated for all the North and Central American species of Tachinus described by Gravenhorst, Erichson, Mäklin, Horn, and Sharp. Diagnostic keys for males and females are included. A brief discussion of the nomenclatural history of the genus, of collecting techniques, and of the major diagnostic characters is included.

The classification of the Nearctic species of the subgenus Orthocladius (Orthocladius) van der Wulp is revised; keys to species for males, females, pupae, and larvae are given; 65 characters in the adult male are taxonomically evaluated; and keys to and diagnoses of the species of the subgenera of Orthocladius for males, females, pupae, and larvae are given. Twenty-nine names of O. (Orthocladius) are recognized as valid. Redescriptions of 17 previously-known species and descriptions of 11 new species are presented. The new species are: O. appersoni, O. charensis, O. clarkei, O. cooki, O. hazenensis, O. hellenthali, O. knuthi, O. oliveri, O. robacki, O. subletti, and O. tryoni. Orthocladius paradorenus (Roback) is considered as a synonym of O. obumbratus Johannsen, and O. currani Sublette is considered as a synonym of O. dorenus (Roback); O. nanseni Kieffer and O. sordens Johannsen are considered as nomina dubia; O. bifasciatus Malloch and O. clepsydrus Coquillett are incertae sedis. Lectotypes are designated for Chironomus decoratus Holmgren, O. dentifer Brundin, O. excavatus Brundin, O. lapponicus Goetghebuer, O. obumbratus Johannsen, and O. trigonolabis Edwards. Orthocladius dentifer Brundin, O. excavatus Brundin, and O. smolandicus Brundin are new records from North America. Orthocladius glacialis Kieffer probably does not occur in North America. Orthocladius oblidens (Walker) is accepted as the type-species of the genus Orthocladius.

This paper treats of larvae of 45 families of North American Diptera which are associated with dead and living trees. A key and illustrations are provided for identification of 43 families whose larvae are sufficiently well known. Also provided is a description of the larvae of each family, the type of larval–tree association, and wherever possible, notes on the life history and behaviour, and an inventory at generic or specific level of the fauna involved.

The species of the tribe Blondeliini of North and Central America and the West Indies (including Trinidad) are grouped into 55 genera. Included is an illustrated key to the genera, a diagnosis of each genus, a list of all generic synonyms, and a taxonomic catalogue of all species recorded from these regions, including their New World synonyms. Type status, type locality, and depository of primary type material is given for each nominal species. One hundred and seventy-seven new generic-level synonyms, 67 new species-level synonyms, and 321 new combinations are proposed. Didyma fuliginipennis Wulp, belonging to the tribe Eryciini, was assigned to the genus Ametadoria (see under lectotype designation of Didyma volucris Wulp). Three new species are described: Ligeria latigena n. sp., from Yukon; Policheta crassisetosa n. sp., from Oregon; and Steleoneura novemmaculata n. sp., from Yukon, Banks Island, and Victoria Island. Lectotypes are designated for 93 nominal species.