Parasitoids of adult corn leafhoppers, Dalbulus maidis (DeLong et Wolcott), were studied in irrigated maize (Gramineae) growing during the dry season in Mexico. Dalbulus maidis was parasitized by Metadorylas spinosus (Hardy) (Diptera: Pipunculidae), Halictophagus naulti Kathirithamby et Moya-Raygoza (Strepsiptera: Halictophagidae), and Gonatopus bartletti Olmi (Hymenoptera: Dryinidae) at 24 of the 54 sites where D. maidis were collected. Greater rates of parasitism occurred at higher elevations (R2 = 0.41) and at more southern latitudes (R2 = −0.52). Metadorylas spinosus is a previously unreported parasitoid of D. maidis, and this is the first report of H. naulti parasitizing Dalbulus elimatus (Ball) and Dalbulus gelbus DeLong. Gonatopus bartletti has the broadest geographic and temporal distribution of the parasitoids found.

The eye-spotted bud moth, Spilonota ocellana (D. & S.), has a long history as a pest in Nova Scotia apple orchards, serious damage by it being reported as early as 1891 (Fletcher, 1892). Its status has fluctuated considerably, the most notable outbreak reaching its peak in 1927. This outbreak occurred when dusts were being used for the control of orchard pests, and (Kelsall 1932) was one of the two main reasons for abandoning the general use of dusts after 1927. The bud moth declined rapidly after 1927 and by 1931 was rated a minor pest (Gilliatt, 1932a). After flutuating at relatively low levels for seven years, it increased in importance and by 1942 was again a major pest. From 1942 to 1952, there was little change in its general status although large fluctuations in population were observed in orchards in which certain insecticides had been used (Stultz, 1950). During 1953, there was a marked decline in the average population level although reductions did not occur in all orchards.

The European pine shoot moth, Rhyacionia buoliana (Schiff.), was introduced accidentally into Ontario about 1925, and has since spread throughout the southwestern part of the province south of a line from the south shores of Georgian Bay on the west to Brockville on the east (Fig. 1). Damage to the host is done by the larvae, the feeding of which results in the deformation of the branches and main stems, reducing the potential value of the trees as timber and, in heavy infestations, making young trees unsuitable for the Christmas tree trade. Several species of exotic and native pines are attacked; red pine, Pinus resinosa hit,, Scots pine. P. sylvestris L., and Mugho pine, P. mugho Turra, being the most susceptible. Because of the extensive planting of Scots and red pine in southern Ontario, especially during the last 25 years, the increasing numbers of European pine shoot moth in this area present a problem of great importance. Contributing to an understanding of this important pest, this paper presents a detailed review of the parasites obtained in Ontario since 1954, with some notes on earlier surveys.

The egg and larval instars of Pachybrachis peccans Suffrian and P. bivittatus Say are described and illustrated. Adults of both species appear in late May, feed on willow leaves, mate and oviposit in June–July. The larvae, unable to climb the host plants, feed in the leaf litter of dead leaves of willow; they reach the second-last or last instar by the end of the fall; then they seal their case and overwinter. Pupation occurs the following spring, probably in early May.

Larval instars can be distinguished as follows: first instar with egg bursters on meso- and metathorax, with typical head chaetotaxy consisting of flattened-papillate setae and 1 pair of very long simple setae, and tibiae with 2 pairs of spiniform setae; older instars without egg bursters, and showing differences in size, in head and pronotal chaetotaxy, and in the number of spiniform setae on the tibiae.

In the larvae, the premental sclerites of the head seem to be present throughout the Campsomata, a group with case-bearing larvae and not only in the Lamprosomatinae as previously reported.

Effects of photoperiod, time of year, temperature, and an insect growth regulator (fenoxycarb) on ovarian development rate in overwintering pear psylla, Cacopsylla pyricola (Foerster), were determined. Winterform pear psylla were collected from the field at intervals between October and February, and reared at 20 °C and one of three treatments: short-day photoperiod, long-day photoperiod, or short-day photoperiod + fenoxycarb. Insects were then dissected at intervals to score ovarian development. Baseline scores (i.e., ovarian development in the field on date of collection) increased very slowly between October and February. By mid-February, only about 20% of insects in the field were categorized as having postdiapause status based upon ovarian development. In the laboratory, time required for insects to reach postdiapause status decreased between the October and February collection dates. Number of days necessary for 50% of the long-day insects to reach postdiapause status was approximately 2 weeks in October, 6 days in December, and < 2 days in February. Short-day insects also required fewer than 2 days in February, but required > 2 weeks in the October and December samples. Our results suggested that insects collected in January and February had completed diapause but that ovarian development was subsequently prevented in the field by low temperatures. Fenoxycarb caused rapid ovarian development even in October-collected insects; rate of development was only slightly more rapid in the February-treated psylla.

Intensive studies on the damage and losses of flue-cured tobacco caused by the dark-sided cutworm, Euxoa messoria (Harris), were carried out in the field at Delhi, Ont., during 1967 and 1968. A new method for estimating the accurate tobacco crop losses is illustrated. Assessment of damage of the tobacco plant and the population density in relation to the yield are described. The yield was significantly related, negatively, to the dark-sided cutworm density, and was reduced in the cutworm-damaged blocks in comparison with the yield in the undamaged check blocks. Assessment of average losses caused by the species was 17% of marketable tobacco, which, based on the average current prices, would amount to 200 dollars per acre or approximately 25 million dollars over the country as a whole every year.

Five species of Trichomalopsis Crawford associated with Haematobia irritans (L.) (horn fly), Musca domestica L. (house fly), Musca autumnalis DeGeer (face fly), and Stomoxys calcitrans (L.) (stable fly) in North America are reviewed. The species Trichomalopsis americana (Gahan), Trichomalopsis dubia (Ashmead), Trichomalopsis sarcophagae (Gahan), Trichomalopsis tachinae (Gahan), and Trichomalopsis viridescens (Walsh) are described, keyed, and differentiated from other recognized North American species. Lectotypes are designated for T. dubia, T. sarcophagae, and T. tachinae. Distribution and host associations are recorded for the species. Trichomalopsis americana and T. viridescens are newly recorded as parasitoids of M. domestica; T. dubia and T. sarcophagae are also newly recorded as parasitoids of Hypoderma lineatum (Villers) (common cattle grub) and Hypoderma bovis (L.) (northern cattle grub), respectively. Some previously published host associations and parasitoid identifications are corrected based on examination of voucher specimens. The known biology of each species is reviewed. The presence of Trichomalopsis albipilosa (Gahan) in North America is considered to be erroneous based on a misidentification of T. americana.

The literature contains numerous references to observations and investigations on various aspects of the biology of many species of black flies. During recent studies on the blackfly fauna of Utah, observations were made on mating, feeding, and oviposition of several species of black flies for which such data are fragmentary or completely lacking.

During studies on blood circulation in the wings of insects it was observed incidentally that the pterostigma (“stigma” of some authors) in some insects had little in common with the similarly-termed structure in others. At the same time some of them were structurally similar to areas not generally identified as pterostigmata in the wings of other species. In view of the general recognition of pterostigmata as an obvious feature in certain insect wings, the apparent mis-interpretation of their nature, and their possible significance in wing evolution, it seems useful to comment on their structure and possible origins.

The apple maggot, Rhagoletis pomonella (Walsh), is an indigenous North American insect whose principal native host is hawthome, Crataegus (Bush 1966). During the past ca. 120 years, this insect has expanded its host range to include fruits of the following introduced plants: apple, Malus sp. (Walsh 1867); domestic plum, Prunus sp. (Herrick 1920); sour cherry, Prunus cerasus L. (Shervis et al. 1970); apricot, Prunus armeniaca L. (Lienk 1970); and pear, Pyrus sp. (Prokopy and Bush 1972). Continuous populations have been established on apple and sour cherry, but apparently only occasional infestations occur on plum, apricot, and pear. Here, we report yet another new host of the apple maggot: the introduced rose hip, Rosa rugosa Thunberg

The effects of parasitism by Hyposoter exiguae (Viereck) on certain developmental parameters of Trichoplusia ni (Hübner) were influenced by host age at parasitism.

Head-capsule growth increments for parasitized Trichoplusia ni became smaller with each successive molt during parasitism so that determination of instar on the basis of head-capsule width became impossible.

Parisitized T. ni showed a proportionately smaller gain in weight from time of stinging until parasitoid emergence the older they were when stung (6 times for 3rd instars; 2 times for 4th instars; and no gain for 5th instars). This retardation was evident 24 h after parasitism. Essentially the same results were obtained for dry weight.

Percentage dry weight of parasitized larvae tended to increase over control values until the 5th stadium when controls abruptly increased. Values for parasitized 5ths remained below the controls. Values found on the last days reflected those of the parasitoid which composed most of the mass inside the host cuticle.

Hemolymph specific gravity in controls and parasitized 3rd instars oscillated with a frequency of one stadium in the 3rd, 4th, and early 5th stadia. Specific gravity of controls then rose to a maximum of 1.0501 in the prespinning phase and dropped by the pharate–pupal phase. Values for parasitized larvae in the 5th stadium rose slightly before leveling off, and parasitized 5th instars rose to a maximum on the next-to-last day. Maximum values attained for hosts parasitized as 3rd and 5th instars never reached that for controls on day 11. This may be related to the complete unacceptability or unsuitability of T. ni larvae for parasitism from day 11 on.

Concentrations of the insecticide fenitrothion in water varied greatly among streams, depending upon spray history and weather. Sprays at 3 oz/ac (210 g/ha) resulted in measurable concentrations in streams as far as 2.5 mi (4 km) from the sprayed area. Concentrations (usually < 15 ppb) diminished quickly in fast flowing streams, and still faster when a spate followed spray application.

Orgilus obscurator (Nees) (Braconidae) and Temelucha interruptor (Grav.) (Ichneumonidae), parasites of the European pine shoot moth, Rhyacionia buoliana (Schiff.), were imported from Europe and released in Waterloo County Reforestation Area, near Elmira, Ontario, from 1955 to 1959.

O. obscurator is the only braconid of known economic importance as a parasite of the shoot moth in Europe (Thorpe, 1930). Recent importations showed that it is also the most abundant parasite of this host throughout Europe.The species was first imported from England in 1928, but was present in Canada earlier (Watson and Arthur, 1959) which suggests an earlier accidental introduction with the host. A total of 8,878 adults were released in Ontario in 1928 to 1949 (Coppel and Arthur, 1954) and 7,912 in 1955 to 1959.

In the eastern deciduous forests of North America, oaks (Quercus spp.) that have been weakened by stress are often attacked and killed by the twolined chestnut borer, Agrilus bilineatus (Weber) (Dunn et al. 1986a). This borer attacks stressed and dying trees but does not attack healthy or dead trees (Haack and Benjamin 1982; Dunn et al. 1986a, 1987).

Adults of Chrysolina quadrigemina (Suffr.) from Westbank, British Columbia, were compared with those from Lotus, California, for differences in behaviour, physiology, and colour in association with adaptation to the long, cold winters at the former location. It was found that the Westbank beetles tend to seek shelter more readily from freezing temperatures than do those from California. They also lay more eggs, as measured during 41/2 months of their oviposition period. Most eggs from both populations probably hatch in spring. The proportion of bronze beetles in the total population correlated with high mean and mean minimum temperatures in the coldest months of the year at 11 collection areas in France, Australia, U.S.A., and Canada.

Six species of predacious Miridae, common to apple trees in Nova Scotia, were used to develop laboratory rearing and feeding techniques for comparing the abilities of predators to consume prey. The test prey species was the European red mite, Panonychus ulmi (Koch), in the winter egg stage. The numbers of eggs consumed per day and per instar in the tests compared favourably with the known predatory values of these mirids under orchard conditions. Both sources of information were used to give the predators a tentative rating. The mirids Hyaliodes harti Knight, Diaphnocoris pellucida (Uhler), Pilophorus perplexus D. and S., and Blepharidopterus angulatus (Fall.) are effective predators, approximately equal to each other in ability to consume the winter eggs of the red mite. The two species Campylomma verbasci (Meyer) and Atractotomus mali (Meyer), which are phytophagous as well as predacious, were less voracious.The results indicate it may be feasible to develop a series of weighting factors, one for each stage of each predacious species, based on ability to consume prey.

One hundred and ten species of insects together with unidentified spiders and pseudoscorpions were collected in foliage samples of Pinus radiata taken from the three natural mainland populations and two planted populations in California. The diversity of the arthropod community in the crowns of P. radiata D.Don was low with 76% of the total number of individuals accounted for by five species groups and 88% by 11 species groups. Spiders were the most abundant species group, comprising 33% of the total number of individuals. The most abundant insect groups were Homoptera, Hemiptera and Coleoptera, respectively. The natural stands supported more species at higher population levels than the planted stands which supported only two species at very high population levels and the rest at low levels. The arthropod communities at the borders of the natural stands were more diverse than at the centers of the stands. The degree of similarity between the natural stands seemed to reflect their geographic distribution; Ano Nuevo and Monterey were most alike and the differences between Ano Nuevo and Cambria were greater than those between Monterey and Cambria. Differences in insect communities within and between the natural and planted stands are discussed in detail.

Eighteen parasitoid species were found associated with obliquebanded leafroller, Choristoneura rosaceana (Harris), and three-lined leafroller, Pandemis limitata Robinson, from 1982 to 1984, on apple and other host plants in the southern interior of British Columbia. The leafroller parasitoids included a Glypta Gravenhorst species (Hymenoptera: Ichneumonidae), Diadegma eureka (Ashmead) and Diadegma interruptum pterophorae (Ashmead) (Hymenoptera: Ichneumonidae), and Hemisturmia tortricis (Coquillett) (Diptera: Tachinidae). The two leafroller species were found on 18 wild host plants from 10 plant families.

This investigation was carried out to determine and explain some of the major factors underlying the variability in concentration of certain bark beetles in slash laid down under different cutting systems. Little is known on the life histories and natural control factors of many of the bark beetles inhabiting lodgepole pine (Pinus contorta Dougl. var latifolia Engelm.) and on the effect which different methods of logging have on the insects. Flash outbreaks in lodgepole pine stands frequently result from the breeding of certain bark beetles in slash remaining after logging operations. The opportunity to carry out this investigation was presented to the Calgary Laboratory in 1952, when the Federal Forest Service initiated studies on selectively cut lodgepole pine. This eventually became a co-operative project between the Federal Forest Service, Department of Northern Affairs and National Resources, and the Calgary Laboratories of Forest Zoology and Forest Pathology of the Division of Forest Biology.