Climatic factors which may control the time of occurrence of seasonal phenomena are discussed, and in particular the role of temperature in initiating periodic cycles in animals in continental North America. The seasonal flight periods of nine species of noctuid moths at two localities in western North America are considered in terms of the lengths of the summer season at these localities. Among the species discussed, those that are in flight prior to midsummer fly earlier, and those that are in flight after midsummer fly later, in the area with a long summer than in the area with a short summer. A factor termed the "phenological date," which is based on the number of days above 42°F in a given area, is proposed as a measure of seasonal development. The factors of photoperiod and temperature that may have a controlling influence on periodic events are discussed. Variance analysis suggests that the phenological date has greater predictive value in estimating the periods of flight of the species considered than have the other factors.

In an attempt to evaluate the importance of physical and biotic factors affecting the distribution of species of the cutworm genus Euxoa, a multivariate regression analysis, as based on a light-trapping survey in western North America, has been conducted. The possible contributory factors have been grouped into four major categories relating to geography, habitat, period of flight, and sample size. Sample size is a composite value reflecting both suitability of habitat and suitability of weather conditions at the time the sample was taken. Geographic factors considered were latitude, altitude, and longitude; habitat factors were mean annual temperature, mean July temperature, mean January temperature, mean annual rainfall and plantform; factors relating to period of flight were calendar date, mean temperature on date of sample, photoperiod, and the phenological date. Except for photoperiod, the variables listed were considered in a quadratic as well as a natural function in the regression analysis. With the number of species of Euxoa as the dependent variable and the factors listed above as the independent variables a total reduction of 76.0% in the residual variance was obtained. When only four variables, sample size, mean annual temperature, mean annual rainfall, and phenological date were employed in a similar regression analysis, however, a reduction of 68.7% in the residual variance was obtained. On the basis of present evidence, it appears that temperature and rainfall are primary factors governing the abundance of species of Euxoa in a given habitat.

Some morphological terms and characters of Chironomidae are discussed. The proposed terminology of the head chaetotaxy is more in accordance with that of other Diptera. The term flagellomere is preferred instead of flagellar segment. The morphology and terminology of tentorium, cibarial pump, maxillary palp, ocelli, and thorax including humeral pit are given special attention. Suggested terminology for the male hypopygium is as follows: gonocoxite and gonostylus for the major genital claspers, volsellae (consisting of claspette and endomere) for the appendices, phallapodeme, sternapodeme, and coxapodeme for the endoskeleton and aedeagal lobe for the "Dritte Spange". The term seta is preferred to such terms as hair, bristle, etc. It is suggested that in the larvae the name premandible be retained for the moment. There seems to be strong evidence for applying the term mentum instead of "hypostomial plate", "hypochilum", or "labial plate". The mentum seems to consist of two plates for which the terms ventromentum and dorsomentum are proposed. The "paralabial plates" are parts of the ventromentum and can be termed ventromental plates. A more correct name for the "glossa" seems to be ligula.

Two methods of analyses, Morris’ key-factor analysis and Varley and Gradwell’s method of analysis, purport to detect density-dependent and density-independent mortality. To test their claims, both methods were used to analyze a life table constructed from a model in which the mode of action of each mortality factor is known. The results show that Morris’ method can detect variation in mortality between generations but it cannot distinguish the density relationships of that mortality. On the other hand, Varley and Gradwell’s method of analysis was found to detect the density relationships of the mortality as it was modeled, when their modified method, the ’proof of density dependence test,’ is used in conjunction with the linear regression of k-value against the density on which it acts.

Holdawayella juglandis Loan, a new species, and some aspects of the anatomy of the final-instar larva of the only other known species of this genus, H. tingiphaga Loan, are described. Host records and field data are reported for both species for Ontario. Though the adults of the two species are very similar morphologically, H. juglandis lacks parthenogenesis, is restricted to the tingid Corythucha juglandis Fitch that breeds only on species of Juglans L., and has specific phenological characteristics. In both species, the head sclerites of the final-instar larva are typically euphorine, and the abdomen bears 3 unpaired, medial, teat-like appendages on segments 5, 6, and 7 whose function is unknown and which do not seem to have homologues in other insect larvae. Both species are single-brooded, lay their eggs in late-instar nymphs and possibly also teneral adults of Corythucha, overwinter as first-instar larvae in adults of these tingids, and complete their endoparasitic and cocoon development in about 90 days during the following spring and summer so that adults of H. tingiphaga begin to emerge from the soil about mid-July and those of H. juglandis about 8 days later. New host records for H. tingiphaga are C. coryli O. & D., C. heidmanni Drake, and C. ulmi O. & D.

In 1968 and 1969 soil samples were collected and bioassayed from 116 fields of crucifers from 14 counties in southern Ontario. Residues of T. ni viruses (nuclear-polyhedrosis (NPV) and granulosis (GV)) were found in soil from 12 counties, being detected in 68 and 45% of soil samples in the respective years. P. rapae granulosis virus (GV) occurred in soil from 7 counties, being found in 18 and 19% of samples. T. ni NPV was more common than T. ni GV. The concentration of viruses of both host species in soil was influenced by density of the host population, crop rotation, soil pH, and month of sampling.

The distributions of attack, gallery length, eggs, and first instar larvae of an endemic population of the western pine beetle in ponderosa pine are described.

Mean gallery length (GL) and larval (L) densities of mature populations are significantly correlated with attack (A) density. The associations are adequately described by the simple linear regressions

The ratios E/GL and L/GL are stable over a wide range of gallery length densities and consequently egg-gallery length and larval-gallery length correlations are highly significant. The regression equations are

All four equations predict values within 10% of observed values.An 88 cm2 sampling unit is satisfactory for sampling either egg or first instar larval populations. Taking four paired sampling units, evenly spaced along the infested bole, from each of four trees per generation, provided a sampling precision of 15%. Increasing the number of paired units to 10 and the number of trees sampled per generation to 9 improved the precision to 10%. If the trees are sampled before oviposition is complete, the number of sampled trees per generation should be increased by 1 for each level of precision.

A method is proposed for rapidly estimating the population levels of European pine sawfly in young red and Scotch pine plantations. On the hypothesis that the numbers of larval colonies per tree are distributed within a stand according to a negative binomial series, it is shown that an estimate Y of the mean sawfly count per tree in any relevant pine stand may be predicted from knowledge of the proportion p of trees infested, by means of the equation

in which k is an estimate of a distribution parameter. The estimate k is derived beforehand, by Maximum Likelihood from a series of insect populations representative of those in which predictions are contemplated.Approximate 95% confidence limits for estimated densities are computed from a variance estimator reflecting two sources of error. The plotted confidence bands pertaining to samples of various size furnish a simple criterion for judging directly from the proportion of infested trees whether or not suppression measures are needed in a plantation.

The phylogenetic relationships between species groups and subgenera in the Forcipomyiinae are presented for the first time, from a consideration primarily of male genitalic structures and comparative morphology of all stages. A dendrogram showing the phylogenetic relationships within the subfamily and a figure showing the evolutionary trends in claspette development in the subfamily are given.The genitalia of Atrichopogon are considered as plesiomorphic and the genus a possible living prototype of all Ceratopogonidae.

The palpus of a fossil crab spider, Xysticus archaeopalpus new species, is described. It was found in peat beds of the Lava Camp Mine near Deering, Alaska. This species belongs in the loculpes group, and is closely related to the extant species, Xysticus britcheri Gertsch. The peats are overlaid by basalt dating 5.7 million years old by the K/Ar method. Regional and local paleo-environmental conditions, based on evidence provided by plant and insect fossils, are discussed.

Larvae of the blowfly Lucilia sericata were shown to require more sodium in their diet than do larvae of Pseudosarcophaga affinis. A chemically denned diet, originally designed for P. affinis, and modified by the addition of agar to suit L. sericata, was further improved by substituting 0.04 g/l. of NaOH and an equivalent amount of KOH.

A small microenvironment cabinet was constructed to facilitate studies on the influence of temperature, humidity, and light on the efficacy of chemical pesticides. The semi-jacketed system operated in the ranges of 4°–36 °C, 20–90% relative humidity, and 0–180 ft-c.