Samples of the Douglas-fir bark beetle, Dendroctonus pseudotsugae Hopk., taken from two different segments of the infested bole were different in gallery production, egg deposition, and yolk deposition. The same two groups were distinguished by comparing fat body cell nuclei taken before the onset of the reproductive period. Techniques for comparing nuclei involved creation and analysis of digital images of nuclei. These groups were indistinguishable from each other, at that stage, by any other known method. The two groups differed in total absorbance of Fuelgen-stained nuclei (DNA content) and nuclear area. Significance of these findings is discussed in relation to early detection of reproduction-related quality differences and population dynamics of bark beetles.

The North American species of the genera Arpedium Erichson, and Eucnecosum Reitter are revised. Five species are recognized, the holarctic species E. brachypterum (Gravenhorst), E. tenue (LeConte) and E. brunnescens (J. Sahlberg), the transcontinental boreal species A. cribratum Fauvel and the eastern United States species A. schwarzi Fauvel.

Lectotypes are designated for E. brachypterum, A. cribratum, A. angulare Fauvel (= A. cribratum), and A. schwarzi. The following new synonymy is established, Arpedium norvegicum var. sallasi Munster and Eucnecosum meybohmi Lohse (= E. tenue) and Arpedium angulare Fauvel and A. columbiense Hatch (= A. cribratum). All genera and species are described and illustrated with scanning electron photomicrographs and line drawings, four maps showing the North American distribution of each species are provided, and keys are presented to aid in the identification of all the species as well as the European species Arpedium quadrum (Gravenhorst). All available records and biological data for the species are summarized.

The use of the generic name Eucnecosum Reitter is discussed and the transfer of brachypterum, tenue, and brunnescens from Arpedium to this genus by Lohse is confirmed.

Eggs of the red turnip beetle, Entomoscelis americana Brown, and seeds of Candle cultivar of Brassica campestris L. and Regent cultivar of B. napus L. (Cruciferae) were exposed to seven constant temperatures (10°–25 °C). At each temperature, egg hatching occurred about 1.0–1.5 days sooner than germination in B. campestris and 1.5–2.25 days sooner than germination in B. napus. Also, germination took place about ½ day sooner in B. campestris than in B. napus. These data indicated that the eggs of E. americana and the seeds of B. campestris and B. napus respond similarly to changes in temperature. Newly-hatched larvae of E. americana were starved for 0–8 days at 15°, 20°, and 25 °C. Starvation-related mortality was not high until they had been starved for more than 2–4 days at 15 °C and 1–2 days at 20° and 25 °C, indicating that the first instar larva has a relatively-limited capability to withstand starvation. Among the survivors, the developmental times for most of the starved larvae were significantly longer than those for the unstarved larvae, but the weights of the adults from starved and unstarved larvae were similar, suggesting that starvation delayed growth and development, but had no apparent adverse or lasting effects on these processes. An evaluation of the egg hatching, germination, and starvation data and of the atmospheric air temperature and soil surface temperature data for the areas where B. campestris and B. napus are grown in Canada suggested that the first instar larva of E. americana normally should not suffer high mortality due to starvation in growers' fields where volunteer seedlings of these two species are the major larval food.

The immature stages of Lexiphanes saponatus (Fabricius) are the first members of Nearctic Cryptocephalinae to be described as well as to be studied. The egg is coated with oblique ornamentations as in other Cryptocephalinae. The larva shows several resemblances with that of the Palearctic genus Suffrianus from which it is distinguished mainly by its large papillate frontal setae. The pupa resembles in general those of Chlamisinae but bears very distinctive projections on the seventh and ninth abdominal segments. The life cycle of L. saponatus is also very interesting. Unlike most other cryptocephaline larvae which live in the leaf litter and are unable to climb on plants, the larva of L. saponatus moves easily on its host plant (Cassandra calyculata) and mimics perfectly the plant buds, becoming almost invisible to the human eye. Although me information is incomplete, it is evident that L. saponatus overwinters in the larval stage, in the first or second instar. It is not known if the larva completes its development during the following warm season or overwinters twice as in other Cryptocephalinae.

Adults of the autumn-emerging capniid stonefiy, Mesocapnia oenone (Neave), were collected from the Bow River in the Canadian Rocky Mountains. After oviposition their eggs were incubated in the laboratory. Successful hatching occurred in the range 2°–15 °C; higher temperatures, except for a short period, were lethal. Eggs subjected to sub-zero temperatures, up to 17 days at −12 °C, also hatched successfully. Within the range 2°–15 °C there was a relationship, linear on logarithmic scales, between water temperature (T °C) and the egg incubation period (Y days), expressed by the equation: Y = 197T−0.59 (r2 = 0.99, P < 0.001). The number of degree-days required for hatching (Z degree-days) increased with increasing temperature (T °C) and also showed a relationship, linear on logarithmic scales, expressed by the equation: Z = 197T0.41 (r2 = 0.97, P < 0.001). In contrast to most other Capniidae, the winter is spent in the egg stage in M. oenone. Our data demonstrate that a combination of a low number of degree-days required for hatching at low temperatures and reduced sensitivity to higher temperatures ensures that egg hatching occurs in the spring. The characteristics of egg development in the autumn-emerging M. oenone are compared with the spring-emerging Capnia atra.

Pelosoma pecki is described as new from specimens from the Florida Keys (Upper Matacumba Key) and from Mexico (Oaxaca). The genus Genyon Smetana 1978 (type-species Cercyon navicularis Zimmerman 1869, from eastern North America) is placed in synonymy with Tectosternum Balfour-Browne 1958 (type-species T. exstriatum Balfour-Browne 1958, from equatorial Africa). A lectotype is designated for Pelosoma prosternale Sharp 1882, and Pelosoma praecursor Smetana 1978 is placed in synonymy with P. prosternale Sharp 1882.

Omicrus intermedius Smetana and the genus Cycrillum Knisch, with the species C. strigicolle (Sharp), are recorded for the first time from North America.

Additional data on bionomics, geographical distribution, and synonymy of many species are presented.

Aeshna tuberculifera Walker and A. umbrosa Walker were studied in the Shenandoah Mountains, Rockingham County, Virginia for 5 years. Both species had 2-year life cycles. They passed the first winter in an embryonic diapause and the second in a larval diapause. Although A. umbrosa was slightly smaller and developed earlier in the year, growth patterns of the two species were similar. Adults emerged from mid-summer to mid-fall with a slight protandry. Sex ratio at emergence was equal in A. tuberculifera but slightly biased toward males in A. umbrosa. Individuals emerging later in the season tended to be smaller than those emerging earlier, and the decline in size was linear over time. The maturation period lasted 4–6 weeks. Poor recovery of marked teneral and breeding adults indicates either high mortality or high dispersal, but observed movement among ponds by marked breeding adults suggests high dispersal. Breeding males of both species defended entire ponds for short periods. Both males and females were present more frequently in the afternoon than during the morning or at mid-day. Females often oviposited in the late afternoon or early evening when males were usually absent from the ponds. A. tuberculifera used stems of Juncus effusus L. almost exclusively for oviposition, while A. umbrosa used a variety of dead plant or other material and rarely used J. effusus stems.

The number of moths captured during short intervals in traps containing a sex attractant for males of the bertha armyworm, Mamestra configurata Wlk., is related to the stage of plant development in the fields of canola (oilseed rape, Brassica napus L.) in which the traps are placed. More moths were captured in fields with plants in the early bloom stage than in those with plants in earlier (leaf, bud) or later (late bloom, pod) stages of development. The effect of this relationship on the total number of moths captured in any field during the entire period of moth flight depended in part on the synchronization of crop development with moth flight. Neither the total number of moths captured per field nor larval density were significantly related to crop development because of high inter-field variability among groups of fields with similar patterns of crop development. Early-maturing fields contained older larvae than later-maturing fields so they should be sampled first to determine larval density and the need for insecticidal application. The estimated patterns of egg-laying were similar to those for male moth capture in early-, mid-, and late-flowering fields. Therefore, male moth captures in sex attractant traps provide a valid index to the abundance of female moths and their egg-laying activities.

Yield saved by insecticidal applications against the bertha armyworm, Mamestra configurata Walker, in commercial fields was measured by comparing yield in protected (unsprayed) plots of 74.4 m2 and in adjacent sprayed areas. Coefficients of variation of yield from sample units 2, 1, and 0.5 m2 ranged from 0.12 to 0.51; statistical precision was increased by taking twenty-five 0.5 m2 sample units per plot. Analysis of pod damage from selected plants predicted percentage yield loss equal to that determined by area sampling.

The results showed that yield saved by control in commercial situations did not exceed 0.325 g/larva, a value that was determined in previous work by field cage trials. Using 1981 costs for spraying and rapeseed prices and a yield loss of 0.325 g/larva, the break-even point for cost-benefit occurs when larval density is 23/m2, a value double the currently recommended density of 10 to 12/m2. Many rapeseed growers therefore are controlling the bertha armyworm at net economic loss, a situation verified by an analysis of 42 separate control decisions made by growers in 1981.

Nymphs and adults of both sexes of six species of grasshoppers, Camnula pellucida, Dissosteira carolina, Melanoplus infantilis, M. sanguinipes, M. packardii and M. bivittatus, were fed wheat seedlings to determine daily feeding rates. The relationships between the feeding rates and five indices of body size were checked with five types of equations — power, parabolic, exponential, linear, and logarithmic. For combined data for all species, the power equation (y = axb) produced the best correlations with the feeding rate being proportional to the 1.56 power of pronotum length, 1.87 of femur length, 1.94 of body length, 0.72 of live weight, and 0.66 of dry weight. The power equation underestimated nymphal feeding and overestimated adult feeding. Better correlations were obtained when separate power equations were used for nymphs and adults. While the b parameters for the nymph equations did not differ significantly from those for the adult equations, the a parameters for nymphs were much larger, reflecting that nymphs ate more relative to their size than adults. For individual species, the parabolic equation (y = a + bx + cx2) was as good or sometimes better than the power equation. Generally, ranking the indices of body size by their coefficients of determination (r2 values) produced the following hierarchy: pronotum length (best), femur length, live weight, dry weight, and body length (worst). However, as the differences between the best and worst indices were minor (usually less than 10%) and as live weight and body length are easy to determine, we recommend the use of either of these two indices for estimating feeding rates.

The reproductive behaviour of the Douglas-fir cone gall midge, Contarinia oregonensis Foote, was studied in the laboratory and in cages outdoors. Adult emergence began in mid-April outdoors and lasted about 2 weeks. Emergence began outdoors at 0600–0700 h Pacific Standard Time, peaked at 1100 h and continued until 1900 h; females dominated emergence early in the day. Mating occurred on or near the duff from which females emerged. Virgin females appeared to “call” males by extending their ovipositors and waving them back and forth, and this behaviour was followed by mating. Laboratory bioassay s using rinses of female abdomens gave further evidence that virgin females produce a sex pheromone. Oviposition behaviour on already infested conelets differed from that on uninfested conelets and suggested the presence of an oviposition deterrent. The mean number of eggs developed by the females was 254, 93% of which were usually laid during the life of the females.

Inclusion of traces of (Z)-11-hexadecenol in synthetic sex lure traps for bertha armyworm moths resulted in diminished trapping; substantial amounts of (Z)-9-hexadecenol or (Z)-11-hexadecenal were also suppressant. Of 22 other oxyolefins tested, (Z)-7-dodecenyl acetate acted in conjunction with the bertha lure components to attract Euagrotis tepperi (Walker) to traps, and (Z)-7-tetradecenyl acetate similarly to attract Lacinipolia vicina (Grote). No tested additive improved either the potency or the specificity of the original bertha blend.

Reproductive performance of Ips calligraphus (Germar) in typical slash pine, Pinus elliottii Engelm. var. elliottii, bark slabs with phloem thicknesses ranging from 0.5 to 4.0 mm was studied at 20°, 25°, and 30 °C during the fall (1981) and summer (1982) seasons by means of radiography and slab dissection. Oviposition rate (eggs/day) and egg density (eggs/cm) were positively correlated with both phloem thickness and temperature, being greatest with a combination of thick phloem (3–4 mm) and warm temperature (30 °C). Gallery construction rate (cm/day) was positively correlated, and length of initial egg-free gallery was negatively correlated, with temperature. Depth of xylem-etching was negatively correlated with phloem thickness. Reproductive performance, as measured by oviposition rate and egg density, was greater in the summer study than in the fall study under similar conditions of phloem thickness and temperature. Nutritional, physical, and seasonal characteristics of xylem, phloem, and outer bark are discussed in relation to the above findings.

Exploratory data analysis was employed to investigate the regional dynamics of managed budworm populations based upon survey data reporting spruce budworm egg-mass densities and damage to balsam fir. The Maine Forest Service collected these data annually from 1975 to 1980 at approximately 1000 different locations each year throughout Maine's spruce–fir forest regions. Although spraying was often associated with ‘better’ conditions in heavily defoliated or infested areas, it was generally associated with somewhat ‘poorer’ conditions in areas which had experienced only light defoliation or infestation in the previous year. The analysis also indicated that while insecticide application may reduce budworm larval populations immediately after application, the largest relative decrease in defoliation rates appeared the year after insecticide application. Insecticide treatments were not as effective as expected. In the year following application, the maximum reduction observed in average defoliation was 20% and in average egg-mass density the maximum reduction was 50%. In many cases the reduction was substantially less. Spraying was not associated with any substantial decline in hazard rating.

Embryological development and hatching for the red turnip beetle, Entomoscelis americana Brown, were studied at 20 °C. In eggs kept at this temperature for > 12 days, embryological development proceeded until a late stage embryo was formed, at which time the embryo entered diapause for the winter. The time required for 50% of the eggs to reach the late embryo stage was estimated to be 11 days. The late embryo stage was not reached before winter in eggs kept at 20 °C for < 11 days, but most of them survived and hatched. Embryogenesis proceeded normally after winter without any apparent adverse effects, and hatching was delayed by the amount of time required to complete embryogenesis. Although it was not essential for the eggs to reach the late embryo stage to overwinter successfully and hatch, a critical minimum stage of development had to be reached during embryogenesis for the eggs to survive. The critical minimum stage of development occurred in the germ band formation stage and was reached during the first 1.5 days of embryogenesis. Most of the eggs laid from 1 to 15 September 1980 and kept outdoors reached the late embryo stage before winter and hatched the next spring; those laid from 15 September to 15 October reached the critical minimum stage of development before winter and also hatched successfully; and those laid after 15 October did not hatch, because they apparently had not reached the critical minimum stage. An evaluation of the data for the eggs kept outdoors and of atmospheric air temperature data suggested that embryo death due to eggs not reaching the critical minimum stage of development before winter normally should not be an important factor in the population dynamics of E. americana in the rapeseed- and canola-growing areas of western Canada. The ecological significance of the data is discussed.

Mean catches of Phyllotreta striolata (F.) in allyl isothiocyanate baited traps decreased southwards from the boreal forest and northern parkland to the central parkland of Saskatchewan, while the opposite was true for Phyllotreta cruciferae (Goeze). Similar trends in the relative numbers of the two species were evident in sweep net catches in canola crops.