In Rhysodini the greatly enlarged mentum forms the entering edge as the beetle wedge-pushes its way through wood. The mandibles cannot bite either wood fibers or food items, but function as a cover for the other mouthparts. The palpi are completely retractile. Each maxilla bears two stylets, the galea and lacinia, and the ligula consists of two bilobed structures. These are apparently the sole feeding structures enabling the beetles to prey on the amoeboid stage of slime molds. The large internal cavity of the head is interpreted as a compromise between a greatly reduced head volume, resulting from reduced jaw musculature, and the need to retain the surface of a full-sized head as part of the wedge-pushing apparatus.

This study determined the importance of Ophiostomatales fungi in the biology of individual adult Ips sexdentatus Boern. in Scots pine. We investigated factors possibly involved in success of rearing without Ophiostomatales, such as the sterilization technique, the presence of antibiotics, and the absence of yeasts. After sterilization of pupae, 866 adult beetles were reared in the media; the proportion of Ophiostoma-free mature adults was 99.2% and total mortality was about 13%. The most preferred rearing method used sterilized pupae which moulted on moistened filter paper and were transferred individually to separate vials where maturation took place on a sterilized phloem medium.The weight and size of Ophiostoma-free mature adults from semi-artificial media and, after establishment in logs, their fecundity and length of their egg galleries, were compared with those of naturally contaminated mature beetles obtained from logs. With the exception of a higher weight observed for adults matured in semi-artificial media, no essential difference was observed between the two groups. Ophiostomatales do not appear to play an essential role in the maturation and fecundity of I. sexdentatus adults.

Sweep-net and sticky-trap data were used to examine the influence of time of day (morning, afternoon, evening), trapping location (pasture, bog, fen, regrowth, and mature forest), and meteorological factors (wind, temperature, saturation deficit, and light) on adult female fly catch for three species (species complex) of black flies — Simulium truncatum/venustum complex, Prosimulium mixtum, and Stegopterna mutata (triploid). Wind speed, light, temperature, saturation deficit, and time of day were all shown to have a significant effect on mean catch, although effects varied among species. After accounting for weather and time, trap location was shown to have a significant effect on mean catch. The effect of site on the mean fly catch of S. truncatum/venustum complex varied with season (June to July), which may have resulted from a seasonal shift in sibling-species composition. Mean catches of P. mixtum and St. mutata were lowest in traps located in open habitats.

Phenology of fall dispersal into apple orchards is described for winterform pear psylla, Cacopsylla pyricola Foerster, in orchards located in Yakima and Wenatchee, Washington. Psylla in both regions first appeared on pear in mid to late September, reaching peak densities in late October or early to mid November, and then decreased in numbers to a low in December. Movement onto apple began in October; peak counts on apple occurred in late November to early December. There was considerable variation among years in phenology of leaf fall in pear and numbers of psylla entering apple. Leaf fall in pear was delayed in a cool, wet fall (1991) compared with warmer and drier years (1990 and 1992), and temperatures during leaf fall were consequently lower in 1991. Numbers of psylla moving onto apple were considerably lower in 1991 than 1990 or 1992. Catch on sticky traps and dispersal rates onto apple were both positively correlated with rates of leaf fall in pear, temperature, and density of psylla on pear.

Metamasius callizona (Chevrolat), a previously obscure weevil species known from Mexico, Guatemala, and Panama, was discovered in Florida (USA) in 1989. In Mexico and Florida its larvae mine meristemmatic tissue and flower-stalks of epiphytic Tillandsia bromeliads, which they kill. In Florida, populations of Tillandsia utriculata L. are being decimated; the weevils also mine and kill introduced ornamental bromeliads of 12 other genera, including Ananas. Fruits of Ananas comosus (L.) (pineapple) are destroyed. Where they occur in southern Florida, populations of the weevil are now much greater than could be found in Mexico in July 1992. In Florida, M. callizona seems to breed throughout the year. Females deposit eggs singly into slits cut in leaf bases of the host-plants. Fully grown larvae pupate in a fibrous cocoon, and development time from oviposition to adult is approximately 11 weeks in the laboratory. No insect parasitoids of the weevil have been found, but Beauveria bassiana (Balsamo) was found as a pathogen in Mexico.

Larvae of the hemlock loopers Lambdina athasaria (Walker) from Vermont and L. fiscellaria (Guenée) from Maine are described for color, chaetotaxy, and gross morphology of the head, body, and legs. Body color varies from pale white-grey to dark green-brown with pigmented sclerotized bands. Head capsule color varies from pale grey-white to dark brown, with dark sclerotized spots of variable size. Many L. fiscellaria larvae are a lighter color than L. athasaria, but no consistent differences were found. The chaetotaxy of micro- and macrosetae conforms to the Geometridae, but the lack of detailed descriptions for other Lambdina species precludes a generic diagnosis. The homology of setae L and SV in Geometridae requires further resolution, particularly with respect to the presence or absence of L3 and SV2.

Inundative release of Trichogramma brassicae Bezdenko for control of European corn borer was tested in experimental plots in 1991 and 1992 in southern Alberta, Canada, to determine its effectiveness as a potential method of control in sweet corn. The tests were conducted in 1-ha plots, in three different fields of irrigated sweet corn each year, at a release level of about 196 000 wasps per ha. The reduction in European corn borer damage in the release plots ranged from 85 to 87% in 1991 and from 45 to 95% in 1992. The reduction in damage was not significantly different in fields with 25 and 49 release points. General area degree-day accumulation for postdiapause development was not adequate to determine the timing of release for individual fields because European corn borer phenology varied among fields. Total moth catch in pheromone traps, however, was directly related to the number of plants damaged by European corn borer, and releases near the time of peak trap catch produced the greatest reduction in damage.

Kalobittacus masoni, new species, and K. similis, new species, are described from tropical Veracruz, Mexico. Kalobittacus similis is compared with K. bimaculatus Esben-Petersen, the only Mexican species of Kalobittacus heretofore known. Males of all three species and females of the two new species are illustrated, and the species are differentiated in a key.

The various characteristics used to describe Forcipatorina and to fix its limits with Clivinina are analyzed and checked against the different genera concerned. New definitions for the subtribes and a key to the genera included in Forcipatorina are given. It is shown that the genus Stratiotes Putzey s is heterogenous and must be divided into several genera, two of which are described as new: Kultianella and Whiteheadiana.

Shortly after the discovery of the introduction of balsam woolly adelgid, Adelges piceae (Ratzeburg), to the south coast of British Columbia, a predator release program was initiated to establish a complex of European and Asian adelgid predators to supplement existing native predators. Between 1960 and 1969, eight species of exotic predators, Aphidoletes thompsoni Mohn (Diptera: Cecidomyiidae), Cremifania nigrocellulata Czerny and Leucopis hennigrata McAlpine [=Leucopis sp. nr. melanopus Tanas. (McAlpine 1978)] (Diptera: Chamaemyiidae), Laricobius erichsonii Rosenhauer (Coleoptera: Derodontidae), Aphidecta obliterata (L.), Scymnus (Pullus) impexus Mulsant, and Scymnus (S.) pumilio (Weise) (Coleoptera: Coccinellidae), and Tetraphleps abdulghani Ghauri (Heteroptera: Anthocoridae), were released (Clark et al. 1971; Schooley et al. 1984).

In the scope of a worldwide revision of the genus Myzocallis, a key of the following subgenera is presented: Agrioaphis Walker (type: Aphis myricae Kaltenbach), Californicallis subg.nov. (type: Myzocallis agrifolicola Richards), Castaneomyzocallis Quednau and Remaudière (type: Aphis castaneae Fitch), Globulicaudaphis Hille Ris Lambers (type: G. pakistanica H.R.L.), Lineomyzocallis Richards (type: Aphis bella Walsh), Myzocallis s.str. (type: Aphis coryli Goeze), Neodryomyzus subg.nov. (type: Myzocallis polychaetus David), Neomyzocallis Richards (type: Callipterus punctatus Monell), Paramyzocallis subg.nov. (type: Myzocallis tenochca Remaudière and Quednau), and Pasekia Aizenberg (type: Hoplocallis komareki Pasek). Four new species of Myzocallis living on various species of Quercus in southern Europe, Turkey, Iran, and Pakistan are described: M. (Neodryomyzus) naumanni sp.nov., M. (Pasekia) mediterraneus sp.nov., M. (P.) persicus sp.nov., and M. (P.) tauricus sp.nov., and a new subspecies, M. (Agrioaphis) castanicola leclanti ssp.nov., host-specific to Castanea in southern Europe. Keys are given for the species belonging to the palaearctic subgenera of Myzocallis.

A brown-sugar flotation technique, recovery trays, and fruit dissection, three methods for determining numbers of larvae of Rhagoletis mendax Curran (Diptera: Tephritidae) from lowbush blueberry fruit, were tested at Kentville, Nova Scotia, in 1990. Similar numbers of larvae were detected by each method, with an average of 3.3, 5.2, and 17.3 larvae recovered at low, medium, and high levels of infestation, respectively. Recovery trays require a minimum of labour but results are available only after 2 weeks, and thus they are of no use for rapid determination. For quality or quarantine inspections, brown-sugar flotation should be used.

Diaeretiella rapae M'Intosh is a cosmopolitan parasitoid of several pest aphid species in agroecosystems, including the Russian what aphid, Diuraphis noxia (Mordvilko) (Mackauer and Stary 1967). In recent years, D. rapae has been imported into the United States from regions throughout the world for D. noxia classical biological control. Knowledge of the alternative hosts of D. rapae could be useful for identifying ecosystems into which the parasitoid could be released at times when D. noxia is absent. Over 30 aphid species are listed as hosts of D. rapae (Mackauer and Stary 1967). This host list, though comprehensive, is a compilation of information gathered from diverse, mostly unrelated sources, and does not necessarily depict the host range of any particular population. Host range differs among populations of some aphidiid species collected from different regions or from different hosts in the same region (Powell 1986). Thus, published host lists can be misleading if they are the sole source of information used to determine acceptable alternative hosts on which to release prospective candidates in classical biocontrol programs. The purpose of this study was to determine the relative suitability of several aphid species common to agricultural and associated non-agricultural ecosystems in the Great Plains as hosts for this Syrian D. rapae isolate in laboratory no-choice tests.

Seven species of Nabicula Kirby occur in Canada: N. americolimbata (Carayon), N. flavomarginata (Scholtz), N. limbata (Dahlbom), N. nigrovittata nearctica (Kerzhner), N. propinqua (Reuter), N. subcoleoptrata Kirby, and N. vanduzeei (Kirkaldy), of which N. limbata is officially recorded for the first time for North America. A faunistic review of the species, key to all taxa, generic diagnosis, and characters distinguishing male and female last-instar nymphs are presented. As appropriate for each species, die following are provided: synonymy, description of adult, wing polymorphism, taxonomic comments, detailed geographical distribution, bioecology, and illustration of important structural characters and nymphal instars. The last-instar nymphs of N. americolimbata, N. nigrovittata nearctica, N. propinqua, N. subcoleoptrata, and N. vanduzeei are described and illustrated for the first time. The biogeography of Nabicula is considered with regard to species diversity patterns, ecological assemblages, species distribution patterns, and relationships between macroptery and geographical distribution.

Species richness and relative abundance of arthropod taxa from an Upper Cretaceous (Campanian: 75 Mya) amber deposit in Alberta are described. About 130 hexapod species have been recognized to date from this deposit, making it the most diverse Cretaceous insect assemblage so far known. Taxa present, in order of abundance, are Hemiptera (66 specimens per kg), Diptera (28), Acari (21), Hymenoptera (13), Aranaea (12), Psocoptera (4), Coleoptera (2), Blattodea (1), Thysanoptera (1), and Trichoptera (0.6). Representatives of Lepidoptera, Collembola, Dermaptera, Mantodea, Phasmatodea, and Ephemeropteraare are also present. In the total of 65 identified families, 15 are extinct. Only one of about 77 genera identified in this deposit is extant. All recognized species are extinct. In comparison, virtually all families reported from Baltic and Dominican Republic ambers are extant, as are the majority of the genera. Morphology and feeding structures are well within the variation seen in modern insects. It is hypothesized that the taxonomic structure of modern insect communities was well established before the end of the Cretaceous and that the structure and interrelationships of insect guilds were also very similar to those of today.

Eight species of Strepsiptera have been reported so far from Florida, but none from the Bahamas. This study reports five species from southern subtropical Florida, and one species from Andros Island, the Bahamas. Of these, Floridoxenos monroensis gen.nov., sp.nov. Kathirithamby and Peck (Corioxenidae: Corioxeninae) is described and added to the subfamily Corioxeninae based on the 4-segmented tarsi without claws; Strichotrema beckeri (Oliveira and Kogan) (Myrmecolacidae) of Brazil is reported from the United States for the first time; a second record for Elenchus koebelei Pierce (Elenchidae) from Florida is reported; and Caenocholax fenyesi Pierce (Myrmecolacidae) is a new record for Bahamas. This latter species is generally a widespread parasite of fire ants in the southern parts of North America, in the West Indies, and in the northern Neotropics.

Action thresholds for imported cabbageworm, Pieris rapae (L.), diamondback moth, Plutella xylostella (L.), and cabbage looper, Trichoplusia ni (Hübner), were evaluated on two cultivars of cabbage, Brassica oleracea var. capitata (L.), in Prince Edward Island. Thresholds were tested on plots of mid-season cabbage, cv. Minicole, and late-season cabbage, cv. Lennox, both grown for fresh market in 1991 and 1992. Management of larval populations at a threshold of 0.25 Cabbage Looper Equivalents (CLE) per plant resulted in yields equal to those obtained with bi-weekly applications or grower treatments. Higher thresholds of 0.50 and 1.0 CLE per plant were not as useful and did’ not consistently result in yields greater than untreated plots. Use of the threshold of 0.25 CLE per plant reduced the number of applications of insecticides by 30% compared with spraying insecticide at bi-weekly intervals from heading to harvest, and 43% compared with management by the grower without regard to insect populations or growth stage of the crop.

Species of Agabus of the lutosus-, obsoletus-, and fuscipennis-groups, as defined by Larson (1989), are revised. Members of the lutosus- and obsoletus-groups are restricted to the Cordilleran and Great Plains regions of temperate western North America. Within this region, the species of each group are largely parapatric. Three species are assigned to the lutosus-group: A. lutosus LeConte along the Pacific Coast; A. griseipennis LeConte in the Great Basin, Rocky Mountain, and Great Plains regions; and A. rumppi Leech in the southern deserts. Agabus lutosus and A. griseipennis hybridize in the Pacific Northwest; A. lutosus mimus Leech is synonymized with A. lutosus. The obsoletus-group contains five species: A. obsoletus LeConte, A. morosus LeConte, and A. ancillus Fall along the Pacific Coast and the Sierra Nevada Mountains; A. hoppingi Leech in the Sierra Nevada Mountains; and A. obliteratus LeConte, containing two subspecies, A. o. obliteratus and A. o. nectris Leech, new status, with a wide range including the Great Plains and Cordillera but not reaching the Pacific Coast. The four species of the fuscipennis-group, A. ajax Fall, A. coxalis Sharp, A. fuscipennis (Paykull), and A. infuscatus Aubé, are boreal and all except A. ajax are Holarctic. Agabus coxalis is restricted to northwestern North America, the other three species are transcontinental.For each species the following information is provided: synonymy, description, and illustrations of taxonomically important characters; notes on relationships, variation, distribution, and ecology; and a map of North American collection localities. Group diagnoses and keys to the species of each group are presented. A correction to the key to species groups of North American Agabus (Larson 1989) is made with the addition of a couplet to include the obsoletus-group. Lectotypes are designated for A. discolor LeConte and A. obliteratus LeConte.

A new species, Platydipteron balli (type locality near San José, Costa Rica), and first male specimens of Platydipteron are described. Based on these specimens, the genus is transferred from the Aenigmatiinae to the Metopininae. Male terminalia of Postoptica platypezoidea are described, and the genus is placed in the subfamily Phorinae.

Behaviour of locally occurring adult females of seven species of coccinellids was assessed on wooden dowel and paper models that mimicked branching patterns and arrangements of leaf attachments to stems. Ambient temperature and hunger of the beetles were controlled. The movements up or down the main branch of the branch models when contacted from a side branch, duration of searching, and method of leaving leaf models were recorded for 20 beetles of each species.Each species responded to the seven models with different frequencies of behaviours that reflected species-specific modifications of the taxes that lead coccinellids to the tops and terminal parts of plants. Some beetles consistently modified the pattern of responses on die models that was displayed by die species as a whole. The individual modifications could be selected for. The differences in frequencies of behaviours were judged to be sufficient to result in differences in the efficiency with which plants with different architectures were searched.