The preference of the nabid, Reduviolus americoferus (L.), for potato leafhopper nymphs, Empoasca fabae (Harris), and pea aphids, Acyrthosiphon pisum (Harris), was examined using functional response models. The nabid exhibited a type-II functional response to each prey. Handling time was much higher for the aphid than for the leafhopper (3.623 vs. 0.211 h). Instantaneous search rates were also higher for the aphid (0.096 vs. 0.020 h−1). A preference index was calculated using the ratio of the instantaneous search rates. The nabid exhibited strong preference for the aphid; when both prey were present in equal numbers, the nabid consumed 3 times as many aphids. The predator did not switch to leafhopper nymphs as the proportion of leafhoppers was increased.

Quantitative sampling schemes for estimating within-tree populations of attacking Dendroctonus frontalis Zimmerman were investigated. Accuracy and precision of five small sample procedures were affected by the number and location of the sample heights, the number of sample disks per sample height, and the techniques used for calculating infested surface area and average insect density. Best small sample estimates were obtained from samples near the middle of the infested bole. Unbiased, minimum variance combinatorials were derived. High precision estimates were obtained only by sampling the infested bole at frequent intervals.

In June 1922, Hearst Hall, the women's gymnasium on the Berkeley Campus of the University of California, burned to the ground. The heat therefrom caused the deaths of three fine specimens of Monterey Cypress growing nearby, thus setting the stage for a local episode in the interaction between a wood-wasp of the genus Sirex and a parasitic wasp of the genus Ibalia. This particular host-parasite interaction is a widespread one of very ancient origin. The 1922 episode of this interaction was manifested as soon as the three dead cypress trees lhad attained a condition which was particularly attractive to the females of Sirex and the females of Ibalia. The larvae of Sirex burrow in and feed upon the timber of coniferous trees; the larvae of Ibalia live parasitically within the Sirex larvae and ultimately destroy them.

A revision of the Canadian species of the genus Silusa Erichson is presented. In this contribution, we treat six species recently discovered in Canada, one of which is a new species from Alberta, Silusa langori Klimaszewski sp. nov. The distribution records for two species are greatly expanded. Silusa californica Bernhauer is now known from Alaska, Minnesota, Alberta, Quebec, New Brunswick, and Nova Scotia (previous records: British Columbia, California). Silusa vesperis Casey is now known from Washington and British Columbia (previous record: California). For two other species, there are first records for Canada and one new United States state record. Silusa alternans Sachse is now known from Quebec, New Brunswick, Nova Scotia, and New Hampshire (previous records: Georgia, New York), and Silusa densa Fenyes is now known from Alberta (previous record: California). Silusa valens Casey is here considered as a synonym of S. alternans. Silusa rutilans Casey and S. modica Casey are confirmed to belong to Leptusa Kraatz, and both are here considered as new synonyms of Leptusa canonica Casey. Silusa gracilis Sachse and S. nanula Casey are also confirmed to belong to the genus Leptusa. The following lectotypes are newly designated for species described on the basis of syntypes: S. alternans Sachse and S. californica Bernhauer. New data are provided on the systematics, relationships, bionomics, and distribution for all Nearctic species of America north of Mexico. Diagnoses and illustrations of external and genital features are provided for all species, and the distribution of each is discussed and shown on maps. A key to the species occurring in Canada is presented.

The cinnabar moth, Hypocrita jacobaeae (L.), is the principal enemy of tansy ragwort, Senecio jacobaea L., in Europe. To determine if this moth could be safely liberated in Canada to control tansy ragwort, breeding stocks were imported as pupae from Sweden and Ireland for laboratory feeding tests. Larval feeding tests with various important economic plants before the moth was introduced to New Zealand from Britain (Cameron, 1935), to Australia from Britain (Currie and Fyfe, 1938), and to the United States from France (Parker, 1960) showed that the larvae would not survive on any of those tested. Such investigations specifically excluded certain crops from damage by the moth but did not indicate the range of plants that can be eaten. It is essential that an insect used in weed control should be highly restricted in its diet. If this restriction is related to nutrient discrimination, as described by Kennedy and Booth (1951) for Aphis fabae Scop., it would be necessary to screen many more economic plants than if it is related to “secondary” plant substances associated with a taxonomic group, as described by Fraenkel (1953). Thus, besides ad hoc tests on important plants, tests to determine the potential host spectrum of an insect are warranted before it is liberated against a weed. The plant spectrum of the cinnabar moth was determined by feeding the larvae on several genera in the tribe Senecioneae and representatives of most other tribes of Compositae that occur in Canada.

The biota associated with Monochamus species collected in Maine include species of Acarina, Diptera, Hymenoptera and Nematoda, as well as fungal and bacterial pathogens.

Mites belonging to seven families and thirteen genera were found in association with the sawyers. Two species were previously unknown and have since been described as the new genus and species Longoseius cuniculus Chant of the family Digamasellidae and the new genus and species Mucroseius monochami Lindquist of the family Blattisocidae. Parasitic diptera belonged to three genera in three different families, and of these one contained a new species, Forcipomyia innom., family Ceratopogonidae, which was found as an intermittent parasite of adult Monochamus notatus and Monochamus scutellatus. This constitutes a new host record for the biting midge family. Only one hymenopterous parasite, a species of Dolichomitus was reared from a sawyer larva. The five genera of nematodes isolated from larvae, pupae, and adults of Monochamus species include specimens of the genus Hexamermis. Parasitism by this group is thought to be unusual because of the relative inaccessibility of the host. Isolates from eight fungal genera were obtained, and strains of Beauveria bassiana, and Isaria farinosa, were shown to be pathogenic. The bacteria isolated from dead sawyers included Aerobacter aerogenes, Bacillus cereus var. mycoides, and one unidentified species. Only the tachinid E. monohammi and the mite Uropoda have been previously reported of the large number of organisms found associated with sawyer beetles in this study. The fungus Beauveria bassiana proved to be the most important biological control agent.

Biological data are given for Coeloides pissodis (Ashmead), Dendrosoter sulcatus Muesebeck, Heterospilus sp., Spathius pallidus Ashmead, Eurytoma conica Provancher, Cecidostiba polygraphi Ashmead, Heydenia unica Cook and Davis, Roptrocerus xylophagorum (Ratzeburg), Rhopalicus pulchripennis (Crawford), Rhopalicus tutela (Walker), and Tomicobia tibialis Ashmead. Only Coeloides pissodis was always closely associated with its host. The other larval parasites were often found disassociated from any host, suggesting an ability to seek out hosts in Ips galleries and the potential to attack more than one host. Observations indicated that pupal parasitism may be significant. Comment on the potential of some parasites as control agents is included.

The intra-nest transmission of two aromatic components of honey bee queen mandibular gland pheromone, 4-hydroxy-3-hydroxyphenylethanol (HVA) and methyl p-hydroxybenzoate (HOB), is quantitatively described. After being secreted onto the body surface of the queen, the greatest quantities of HVA and HOB are removed by workers in the queen’s retinue, especially those contacting the queen with their mouthparts. Other workers acquire pheromone components via direct contact with retinue bees or with other workers that have already acquired queen pheromone. HVA and HOB can also reach workers through queen or worker "footprints," although the relatively little material deposited onto the comb wax becomes less available with time, presumably because of diffusion into the wax. Pheromone material is removed from circulation by being internalized into workers, the queen, and the wax. Rates of HVA and HOB transfer between different entities within the nest are described in terms of pseudo first-order rate constants. The intra-nest transfer of these two components, both qualitatively and quantitatively, is similar to that described earlier for the most abundant queen mandibular gland pheromone component, 9-keto-2-(E)-decenoic acid (9-ODA; Naumann et al. 1991). Thus, the queen mandibular gland pheromone complex is transferred through the nest as a unit rather than as individual components moving at different rates.

In laboratory and field observations, male and female orange wheat blossom midge, Sitodiplosis mosellana (Géhin), emerged in late afternoon and early evening, with males emerging 1–2 h before females on average within a given day. Under laboratory conditions, males also emerged on average 0–3 days before females in three different experiments. Within 1 h of emergence, virgin females began to extend their ovipositors much of the time. This behaviour ceased upon mating, and was presumed to be calling behaviour: behaviour associated with pheromone release. Calling behaviour exhibited a daily rhythm both under controlled and field conditions. Females gradually increased the time spent calling in the last few hours of the photophase and called more than two-thirds of the time during the scotophase. Mating was preceded by wing vibration in the male prior to and during a walking approach. Receptive females spread their wings which facilitated mating. Mean duration of mating was 171 ± 15 s (±SE).

The flea beetle, Phyllotreta striolata (F.), was attracted to the cruciferous plants Brassica oleracea L. and Raphanus sativus L., but not to B. campestris L. and B. napus L. which are important natural host plants, nor to Pisum sativum (L.), a legume. The presence or absence of attraction was demonstrated by exposing small groups of caged plants to natural populations and trapping beetles near the plants. In choice and no-choice laboratory feeding experiments, P. striolata fed on eight Cruciferae in the genera Brassica, Raphanus, and Sinapis but not on P. sativum. Phyllotreta striolata fed less on S. arvensis L. and S. alba L. than on plants in the other genera. Within Brassica, B. oleracea, B. napus, and B. campestris were preferred over B. juncea (L.) Czern and B. nigra (L.) Koch. Discrimination at the attraction phase of host selection did not account for discrimination shown in laboratory feeding experiments nor in the natural attack of flea beetles on cruciferous crops.

Upon transfer to a photoperiod of LD 12:12 all young, reproductively active Chrysopa carnea Stephens, reared and maintained under LD 16:8, showed a rapid decline in fecundity. One group entered diapause, as shown by the cessation of oviposition within 22 to 34 days, fat body accumulation, and an associated colour change. The females in this group resumed oviposition within 3 to 7 days after being returned to LD 16:8. Females in the other group under short-day conditions continued to oviposit, but at a lower rate than those kept under constant LD 16:8. Our data indicate that the imago is sensitive to both long-day and short-day photoperiods and that some males and females enter a facultative reproductive diapause which is induced and terminated in this stage solely by manipulating the adult lighting regimen.

Evidence for secondary attraction in the western balsam bark beetle, Dryocoetes confusus Swaine, was obtained in laboratory bioassays and field experiments. Both sexes showed positive responses to volatiles of the host tree, Abies lasiocarpa (Hook.) Nutt., indicating that primary attraction is probably important in host selection by this species. Male beetles initiated attack and within 6 h produced an aggregation pheromone(s), which was present in frass and in pentane extracts of the abdomens of males excised from logs. Both sexes responded to the pheromone. Abdominal extract of unmated males which had bored into host bark for 14 days was still attractive. Pheromone production was induced by exposing males to host resin volatiles. Mating had no effect on male attractiveness, but induced females to produce an antiaggregation pheromone which, in laboratory bioassays, at least partially inhibited response to male attractant. The attractive volatiles from male-infested logs were successfully captured on Porapak Q®. The development of laboratory bioassay and pheromone extraction techniques indicates that a pheromone isolation program is feasible.

The vernal migration routes of the eastern population of the monarch butterfly (Danaus p. plexippus L.) in North America were plotted from data resulting from the recapture of migrants alar tagged in the overwintering site of the Neo-volcanic Plateau of Mexico. One migrant, which had been alar tagged at Decorah, Iowa, on 3 September 1973, and recaptured 7 months later on 8 April 1974 at Richmond, Texas, led to the conclusion that this particular migrant had flown to the Mexican overwintering site and was recaptured on its return vernal flight. This recapture also gave data indicating that it was not returning to the original breeding area, from which it is concluded that although some migrants may return to the original breeding grounds many may not do so.

Companionate planting is one of many insect control strategies propounded by organic growers. A variety of herbs are purported to possess repellent properties to many insect pests of vegetables (Rodale 1975; Yepsen 1976; Hill 1976; Anonymous 1977a). According to Atsatt and O'Dowd (1976), repellent plants are members of plant defense guilds which prevent herbivores from locating their hosts. Perrin and Phillips (1978) reviewed the elements of natural pest control characteristic of mixed cropping systems and outlined suggestions for transferring these elements to “agronomically acceptable” monocultures. However, very little work has been done to substantiate these claims and field evidence of the protective properties of companionate plants is, therefore, warranted. This becomes all the more important because of the dramatic increase in home gardening recently in North America. It is estimated that 33 million home and community gardens were grown in the United States during 1976 and 1977 (Anonymous 1977b). Here we describe the results of field experiments in which we sought to quantify the effect of companionate plants against major lepidopteran pests of cabbage in southside Virginia.

Populations of pea aphid, Acyrthosiphon pisum (Harris), were sampled through the summer of 1984 on five cultivars and in 1985 and 1986 on six cultivars of field peas, Pisum sativum L., grown in field plots in southern Manitoba. Patterns of pea aphid population growth were generally similar among cultivars in any one year. Aphid populations on all cultivars in all years remained relatively low until mid-July, then increased rapidly, peaked at about the beginning of August, and declined sharply to low levels in late August. At the time of peak aphid numbers, significant differences in aphid population densities were found among cultivars in 2 years; the lowest densities were found on the cultivars Century and Tipu, and the highest densities on Triumph or Trapper. Pea aphid feeding was not detrimental to any yield parameters except 1000 seed weight. In 1984 Triumph and Tara, and in 1985 Triumph had significantly decreased 1000 seed weights in plots in which aphid densities were not controlled. Differences in the abundance of the aphid among cultivars were not reflected in their yield responses. Over 3 years the regression line of aphid densities upon Century seed weight was significantly steeper than those of Trapper, Lenca, or Tara. Trapper was least affected by aphid feeding. Results indicated that the economic threshold of pea aphids on peas other than Century needs to be re-evaluated.

Conceptual and nomenclatural problems of Digamasellus Berlese, 1905 and Dendrolaelaps Halbert, 1915 are reviewed. It is shown that Digamasellus punctum (Berlese, 1904) is conspecific with D. perpusillus Berlese, 1905, the type-species of Digamasellus Berlese, 1905 (new synonymy). Hence, the genus in which punctum is included must take the name Digamasellus.A new case is made for recognizing Digamasellus and Dendrolaelaps as distinct genera in the Digamasellidae. Two other genera of Digamasellidae are recognized, Dendroseius Karg, 1965 and a broadened concept of Longoseius Chant, 1961. Two new subgenera are proposed, Dendrolaelaspis in the genus Dendrolaelaps, and Longoseiulus in the genus Longoseius. Diagnoses, descriptions, and a key to these genera and subgenera of Digamasellidae, along with a comprehensive description of the family, are presented. The phylogenetic relationship of the Digamasellidae in the Rhodacaroidea, and some thoughts on phylogeny within the Digamasellidae are given.A second species of Digamasellus sensu stricto, D. australis, is described as new, and the female and male adults of the type-species of Longoseius, L. (L.) cuniculus Chant, are described for the first time. New combinations include: Dendrolaelaps (Dendrolaelaspis) orientalis (Bhattacharyya), Longoseius (Longoseiulus) longulus (Hirschmann), L. (L.) ornatus (Hirschmann), L. (L.) aberrans (Hirschmann), and L. (L.) brachypoda (Hurlbutt).The absence of the protonymphal seta, md, from the telotarsi of legs II to IV is noted as a singular deficiency in the leg setation of Longoseius cuniculus Chant. This seta is not known to be absent in any other species among the families of Gamasina.A paper published by Hirschmann while the present work was in press is considered in an addendum to this paper. The subgeneric name Dendrolaelaps (Tridendrolaelaps) Hirschmann, 1974 is an objective junior synonym of Digamasellus Berlese, 1905, and the latter also has priority over Dendrolaelaps Halbert, 1915 so long as both names are applied within the same genus. A lectotype is designated for the nominal species Digamasellus punctum (Berlese). The status of the subgenus Dendrolaelaps (Multidendrolaelaps) Hirschmann, 1974 is problematic, pending a more comprehensive diagnosis providing data sufficient to indicate whether this is a monophyletic group. The quadrisetus group is newly proposed for some of the species placed by Hirschmann in the armatus group of Multidendrolaelaps. Digamasellus badenhorsti (Ryke) is tentatively considered as the second known species of Dendroseius Karg. Hirschmann's opinion, that Longoseius Chant warrants no more than a species-group in Dendrolaelaps, is disputed.

In North America, the tribe Cholevini (Coleoptera: Leiodidae) is composed of the genera Prionochaeta Horn with 1 species, Catoptrichus Murray with 1 species, Sciodrepoides Hatch with 3 species, and Catops Paykull with 17 species. The species are mostly forest inhabitants that feed on carrion and other decaying materials, but some occur in tundra habitats, in caves, and in rodent burrows. Resurrected status is proposed for Sciodrepoides terminans (LeConte). The subspecies status of Sciodrepoides watsoni hornianus (Blanchard) is not supported. Lectotypes are designated for Catops terminans LeConte (= Sciodrepoides terminans (LeConte)), Choleva gratiosa Blanchard (= Catops gratiosus (Blanchard)), and Choleva egena Horn (= Catops egenus (Horn)). Neotypes are designated for Catops simplex Say and Catops basilaris Say. Catops luteipes Thomson is reported from North America for the first time. New species are Sciodrepoides latinotum Peck and Cook sp.nov., Catops paramericanus Peck and Cook sp.nov., Catops apterus Peck and Cook sp.nov., and Catops meridionalis Peck and Cook sp.nov. Four Catops species are Holarctic in distribution, whereas the others are restricted to North America, south to Mexico.

Current investigations at the Forest Biology Laboratory, Winnipeg, are being directed towards the formulation of life tables for the larch sawfly, Pristiphora erichsonii (Htg.) (Lejeune, 1955). Because small mammal predation is a major factor in reducing cocoon populations of the sawfly (Buckner, 1953), an adequate method of assessing this source of mortality is desirable

Mountain pine beetle (Dendroctonus ponderosae Hopkins) population dynamics, as well as potential for outbreaks and resulting tree mortality, are related in part to habitat temperature. As a first step in development of a life-stage, event-oriented simulation model, we have modeled the temperature-dependent development of the egg stage. The completed model includes a full description of variation in developmental rates and is capable of predicting duration and eclosion patterns for any temperature regime. This model was parameterized using data obtained from constant-temperature experiments at temperatures of 8, 10, 12.5, 15, 20, 25, and 30°C. Validation experiments were conducted for constant temperatures of 15, 17.5, 22.5, and 27.5°C and for variable-temperature regimes of 15±5 and 15±10°C. Validation results indicated that the model is capable of accurately describing the emergence curve for constant temperatures below 27.5°C. The model also faithfully represents emergence under variable temperatures of 15 ± 10°C. Potential reasons for lack of model fidelity in describing emergence at constant high temperatures and for 15 ± 5°C are discussed in the text.

Adult pear psylla, Psylla pyricola Foerster, from commercial pear orchards near Wenatchee, WA, were tested using a slide-dip technique for susceptibility to fenvalerate over a 5-year period from 1984 to 1988. Results were compared with those from similar tests using psyllids from an unexposed population near Corvallis, OR. During 5 years, resistance of adults to fenvalerate increased by 16- to 32-fold at Wenatchee while that of the Corvallis population did not change. In 1988, tests with five pyrethroids and pyrethroid – piperonyl butoxide combinations indicated that pear psylla adults also were resistant to permethrin and flucythrinate but not to fenpropathrin or cyfluthrin which contain a cyano group that reduces their susceptibility to oxidase metabolism. Piperonyl butoxide synergism was proportional to the level of resistance, indicating that resistance is probably due to increased mixed function oxidase activity. Implications of this study to control of post-diapause winter form adults in commercial pear orchards is discussed.