A highly sensitive bioassay of the olfactory response of I. confusus is described. The response of beetles to air streams carrying attractants is a chemoklinotaxis but positive orientation occurs only in moving air. There is no evidence of ameno-taxis in odorless air streams or orientation to attractants in still air. Male behavior is characterized by an “area” orientation near the attractive material, an indirect approach to the source as shown by their entering adjacent air channels, and stopping frequently in the traverse during which they make klinotactic movements. The females exhibit a “point” or “straight-line” response, crawling directly to the source, rarely deviating into adjacent channels and only occasionally interrupting their approach.

Bark-wood samples of ponderosa pine become attractive 4-6 hours after male beetles are introduced into preformed entrance tunnels, the peak attraction occurring between 18 and 144 hours. Frass is not attractive until 9-12 hours after introduction of males. The ratio of females to males responding positively during the peak attraction period was approximately 8:5. The level of attractiveness to females falls as the season progresses, the highest response being recorded in late May and June. Sexual maturity as judged by the appearance of motile sperm was not correlated with host feeding or the initiation of attraction. Frass of males boring in Douglas fir was unattractive to females.

Attraction is initiated by male feeding in the phloem-cambial tissue of a host and is delayed until the first food has passed through the gut. The attractant appears to be associated with male excrement and may be produced, at least in part, in the hindgut.

In June, 1962, a type of bug injury was found by the junior author to be prevalent in a well cared for apple orchard of 800 trees at Debec, Carleton County, N.B. Adults of the bug causing the injury were collected in early July and determined by Dr. L. A. Kelton, Entomology Research Institute, Ottawa, as Lygidea mendax Reut., commonly known as the apple redbug. This is the first record of this species in New Brunswick.

Many problems in the management of renewable natural resources are extremum problems: we wish to maximize fish yield from a lake, tree yield from a forest, or minimize insect pest survival, for example. Such problems can be handled better by dynamic programming than classical analysis, because of the large number and the complex nature of constraints imposed on such systems. However, a priori arguments and analysis of biological time series show that such renewable natural resources do not constitute Markov processes, since state changes from t to t + 1 are dependent on the state: at t − 1 as well as the state at t. Therefore, before making a decision about the optimal strategy at t, we must explore the future consequences of the strategy at t + 1 and t + 2. This paper reports computer experiments on strategy evaluation procedures, using dynamic programming and modified dynamic programming with two-stage “look-ahead”. The data used to develop the model came from 60 years of observations on weather conditions and insect pest populations at Magdeburg, Germany. The general conclusion from this work is that the selection of most appropriate strategy for a biological management problem should he determined by the structure of the problem. Sometimes, “one-stage look-ahead” gave the lowest value for the criterion function, and sometimes “two-stage look-ahead” was optimal. The two types of programming always yielded lower cumulative defoliation than the method now used: killing as many pests as feasible whenever “pest” densities are reached.

In this paper a new species of Glyphina Koch is described. This genus has not been previously recorded from the Western Hemisphere.

Although Rhopalosiphum padi L. was common on cereals and Gramineae in Ontario, only a small number of R. fitchii (Sand.) were found on one grass plant in 1961. Fundatrigeniae of R. padi from Prunus virginiana L. and of R. fitchii from Crataegus spp. and Malus spp. were transferred to oats and wheat on which alienicolae of R. padi multiplied rapidly, but R. fitchii very slowly. R. fitchii transmitted all but one of the isolates of barley yellow dwarf virus (BYDV) that R. padi transmitted to Clintland 60 oats, but fewer test plants became infected, the incubation period for symptom development was longer and symptoms were less severe when R. fitchii was the vector. Both species infected more test plants after a 5-day than after a 2-day acquisition feed on the virus source. It appears that R. padi, a common and efficient vector of BYDV, has frequently been mistaken for R. fitchii which is not common on cereals and not a highly efficient vector.

A dosage concept is proposed to explain differences in vector efficiencies of R. padi and R. fitchii. It is also suggested that strains of BYDV become ’adapted’ to transmission by a vector species.

By comparing the number of moths caught in box-type traps, attractant light sources can be arranged in the following order of efficiency: 15-watt fluorescent rubes emitting ultraviolet and visible light > 15-watt fluorescent tubes emitting cool white light ≥ germicidal rubes behind glass > 15-watt fluorescent tubes emitting ultraviolet but little visible light ≥ 100-watt mercury-vapour bulbs emitting ultraviolet but little visible light. Noctuoid and large geometroid (sent. lat.) moths discriminate between these light sources on the basis of their spectral content, but pyraloids, other small microlepidoptera and some geometroids probably do not. Pyraloid moths escaped in significant numbers from traps with normal apertures (13/4-inch), after sunrise. They freely entered traps with narrow apertures (1/2-inch) but these traps caught fewer large moths.

Four females of Phaenopria popei oviposited into a one-day-old puparium of Dictya sp. Adult progeny emerged 18 days later at 19-25 °C. Host flies include Dictya, Elgiva, and Sepedon, and probably Tetanocera (all Sciomyzidae).

Nepytia freemani, a new species attacking Douglas fir in British Columbia, is described and compared with its near relatives.

The barley jointworm, Harmolita hordei (Harr.), was first discovered at a point in the northeastern part of Prince Edward Island in 1946. It spread quite rapidly along the northern coastline of the province and more slowly southward, and today infestations may be found in most areas of the province. Inland movement of the pest did not start until about 1955 and since that time infestations have generally been lighter than they were previously.

H. hordei overwinters as mature larvae in galls in barley stubble left in fields after the grain is harvested. Adults emerge the following year during late June and early July and oviposit in the stems of young barley plants, usually when the plants are six to eight inches high. Eggs are almost always laid just above the lower nodes or joints, either on the main or on tillering stems. The adults live for four to eight days. The larvae develop inside the stems and the plant tissue around them develops into hard, woody galls. The larvae mature in three to four weeks and, thereafter, remain dormant inside the galls in the stems until the following year. Infested barley plants are stunted and heads may fail to develop or, if formed, contain small, shrivelled kernels. In severely infested fields, the grain crop is considered a complete loss.

There are six speoies of parasites known to attack H. hordei in Prince Edward Island, and all of them are chalcids that closely resemble the pest. Parasite eggs are deposited in the stem with the host and the larvae attack and destroy H. hordei larvae and then complete their development inside the galls. In addition to biological control by natural parasites, the other major natural control agent is considered to be weather, combinations of moisture, humidity, and temperature. However, further investigations are necessary to establish the influence of these different factors.

While sweeping for Hymenoptera in early June, 1961, in the Gatineau Park region of Quebec, about 15 miles northwest of Ottawa, Ontario, one of the authors took a specimen of the rare and interesting genus Streblocera Westwood. Discovery of this specimen, in a relatively recently glaciated region remote from all localities previously reported for the genus, prompted a search for further material, which however was without avail. Finding the species to be undescribed and also easily recognizable by a number of distinct structural features, the writers venture to present the following description based on the single example at hand.

Four species of Orius Wolff, a Holarctic genus, are known from the Nearctic region. Orius insidiosus (Say) is known from midwestern and eastern United States and eastern Canada, while O. tristicolor (White), shown here to be a valid species, is transcontinental in North America. O. minutus (L.), a common species in the Palaearctic region, is known from western North America. O. pumilio (Champ.) occurs in Florida. The distinguishing characteristics of the species are given, and a key is provided.

Four indigenous parasites of R. buoliana are discussed: Exeristes comstockii (Cress.), Scambus hispae (Harr.), Scambus tecumseh Vier. and Itoplectis conquisitor (Say). The first three are external larval parasites and the fourth an internal pupal parasite. Observations are given on the hosts, life histories, and habits under laboratory conditions. The immature stages are described.

Inoculative freezing of insects is distinguished from nucleative freezing and is treated from the standpoint of the delays observed in freezing. On the assumption that the fine structure of the cuticle regulates the penetration or growth of external ice into the insect's body, the cuticle was experimentally altered by soaking, boiling, and immersion in strong detergent solution. Soaking was of doubtful effectiveness, whereas boiling and detergent hastened inoculation, Detergent also caused many insects to freeze when the contact water froze, with no delay. Rate of inoculation of untreated larvae was directly proportional to the area in contact with ice, and inversely proportional to temperature down to −10 °C. No further rate increase took place down to −15 °C, possibly because the vapor pressure difference between ice and supercooled body fluid does not change appreciably in this temperature range. Larvae froze more rapidly when they had already been frozen and thawed once or twice. No relation between inoculation rate and rate of water loss in a dry atmosphere could be established.

The freezing of water in extremely small spaces is discussed and related to the process of inoculative freezing. Probable pathways of ice growth through the cuticle are considered in relation to known structural characteristics and the results of the present experiments. Two hypotheses are proposed to account for the observed delays in freezing, but neither is wholly satisfactory. The first postulates that the outer extremities of the pathways, through the epicuticle, are hydrophobic and contain air which temporarily separates contact moisture from pore liquids. After freezing of the contact moisture a vapor pressure differential results in a net flow of vapor outwards, the vapor freezing on the ice and building inwards until the ice front touches liquid in a space large enough to allow freezing. This hypothesis assumes the existence of at least one pathway large enough to support ice penetration without hindrance caused by restricted size. The second hypothesis assumes that no such unrestricted pathways are present, all being inadequate in size. Differences in chemical potential between ice and liquid cause pore liquids to move outwards to the contacting ice surface and accrete on its

The life history and the later larval instars of Tetrastichus garryana Burks (Hymenoptera: Eulophidae) are described and figured. The parasite has been collected from several species of oak gall cynipids, to which general group it seems to be restricted. In British Columbia it is most commonly associated with the gall-wasp Besbicus mirabilis (Kinsey).

Descriptions of alate viviparous female, ovipara and male of Pseudocercidis rosae Richards are given, with brief notes on biology of the species on Rosa sp.

Studies in 1961 and 1962 showed that several naturally occurring conditions suppress the pear psylla. Temperatures above 100°F. caused mortality of nymphal stages and reduced adult oviposition. Crystallization of honeydew was a mortality factor in a few instances, and seemed to be associated with high temperature and low humidity. Absence of new growth and poor condition of leaves caused a steady decline in pear psylla numbers in abandoned orchards. Anthocoris antevolens White was an effective predator in unsprayed orchards and significantly reduced pear psylla populations. A parasite, Trechnites insidiosus (Crawford) was encountered, but its significance as a mortality agent was not determined.

Unlike most other arrhenotokous species, D. fuliginosus females cannot control fertilization of their eggs and in an optimal environment the sex ratio of any one strain is constant. Variations in the sex ratio occurred when unfavourable environmental conditions prevailed before, during and immediately following mating. Beyond half their life span, males inseminated less than half the females they mated and the inseminated females produced fewer female progeny. Temperatures above 27 °C. during post-embryonic development sterilized otherwise functional males but had much less effect on females. Structural defects of either sex were rare. Mating was successful only within the normal range for optimal adult activity. Although females were inseminated by more than one male, the sex ratio of their progeny was not affected. Larval mortality from superparasitism above 65 larvae per host differentially favoured survival of males, heightening the incidence of pairing in nature at low host population densities. The percentage females was significantly reduced when oviposition was interrupted, or delayed by low temperature, providing a possible explanation for the numerous reported differences in the sex ratio between laboratory and different geographically located populations.

Ips concinnus (Mannerheim) and Ips mexicanus (Hopkins) comprise Group I of the genus Ips DeGeer (Coleoptera: Scolytidae). Members of this group have 3 spines on each lateral margin of the declivity and strongly arcuate sutures on the anterior face of the antennal club. I. radiatae Hopkins is placed as a synonym of I. mexicanus (Hopkins). I. concinnus breeds in Picea sitchensis in the coastal region from Alaska to southern Oregon. I. mexicanus breeds in various species of pines from Alaska to Guatemala and eastward in the United States and Canada to the Rocky Mountains. A key to the species and descriptions are provided.

North American Ips of Group II (Hopping, 196îb) are I. emarginatus (Leconre) and I. knattsi Swaine. They are the only Ips having the third declivital spine emarginate ar the tip. They breed in various species of pine. The distribution of I. emarginatus is from southern British Columbia to California and eastward to Montana. I. knausi is found in Colorado, New Mexico and Arizona. A key to the species is given. I. plastographus (Leconte) is the sole representative of Group III. It is the only four-spined Ips with the sutures of the autennal club strongly angled at the middle. I. plastographus breeds in species of pine. It occurs from southern British Columbia southward in the western United States and through Mexico into Guatemala. Hosts and more detailed distributions are given for species in Groups IT and III.