The genus Cenocorixa Hungerford is shown to contain only eight valid species. New synonymy and systematic changes are given as is a revised key to males of the genus. Variation is noted in some of the characters used for specific identifications.

Eight new species of Scolytidae are described from Mexico. The new species represent the genera Scolytus (2), Carphoborus (1), Chaetophloeus (1), Cnesinus (2), Phloeotribus (1), and Prochramesus (1). New distributional records are given for nine previously described species and notes on the genus Prochramesus are included.

Mating frequency and behavior of five color-coded adults of each sex of Trypodendron lineatum (Olivier) were observed for 1 hour periods in petri dish arenas. Mating activity was evaluated by recording each incident in which a male assumed the "precopulatory" position on a female for a minimum of 10 seconds. Newly emerged brood adults mated with very low frequency. The mating activity of revived overwintering beetles increased throughout the winter. In February there was a sudden rise in activity to an intensity approaching that of sexually active "spring" populations of March and April. This pattern, as well as the recovery of locomotion upon warming throughout the winter, provides evidence that overwintering populations undergo only a reproductive diapause, or hibernation. Mating activity of excavating parents fell to one-half that of spring beetles within 2 weeks of host invasion and declined further after 4 weeks. Parents that had recently emerged from brood logs had negligible mating activity. Flight was not an essential prerequisite to mating. There was no prolonged delay between initial contact of the sexes and mounting, and no observable courtship. Behaviorally, the male was the aggressive partner; the female was passive and nonresisting. Multiple matings by both sexes, with the same or different partners, and mounting of mating couples and other males by males were observed. The average duration of mounting was 1.75 minutes and, when copulation occurred, 3.35 minutes; dissections showed that this period was sufficient for insemination. Pronounced reduction of mounting and copulation activity occurred within 30 to 40 minutes of initial contact with the opposite sex. Mating frequency depended primarily on the maturity and vigor of the male, although the maturity of females had a slight effect.

The following 14 aphids are known to feed on species of Solidago in Canada: Cachryphora serotinae (Oestlund), Dactynotus caligatus Richards, Dactynotus canadensis new species, Dactynotus erigeronensis (Thomas), Dactynotus gravicornis (Patch), Dactynotus lanceolatus (Patch), Dactynotus macgillivrayae Olive, Dactynotus nigrotibius Olive, Dactynotus nigotuberculatus Olive, Dactynotus pieloui new species, Dactynotus pseudochrysanthemi Olive, Dactynotus tissoti Boudreaux, Dactynotus solirostratus new species, and Macrosiphum goldamaryae (Knowlton). A key and a list of associated host plants are given.

Prosimulium albertense new species is described from southern Alberta, Canada, and is differentiated from the closely related species P. clavatum Peterson.

Seven species groups of Dioryctria are defined on a combination of external and genital characters. Three American species, Dioryctria rossi Munroe, D. auranticella (Grote) and D. disclusa Heinrich, are referred to the auranticella group. Four Asiatic species are also referred to this group. These are D. okui Mutuura, D. castanea Bradley, D. pryeri Ragonot (= Salebria laruata Heinrich), and D. yiai n. sp. All the species feed on conifers. All except D. okui feed on pine, either cones or shoots, or both; D. okui eats the foliage of spruce.

The macro-leafhoppers (Cicadellidae, exclusive of Typhlocybinae) of Manitoba are recorded with distribution and host records for the province, seasonal occurrence of adults, ecological associations, and recent taxonomic changes. These comprise 240 species, including 95 new provincial records, of which 22 are new Canadian records, and 1 is a new nearctic record, ldioccrus marginalis Vil. The westward spread of Athysanus argentarius Mete, and Doralura stylata (Boh.) is commented upon.

Nuisance species of riverine insects were temporarily eliminated from the Expo 67 site at Montreal in 1967 by four applications of an emulsifiable formulation of DDD (TDE) to the St. Lawrence River, one in each of the months of May, June, July, and August of 1967. In each treatment sufficient DDD was applied 1.5 miles above the infested rapids to provide a concentration of about 0.4 p.p.m. of DDD in the water, throughout a period of about 15 minutes. Each treatment caused the immediate detachment of about 98% of the Trichoptera larvae (mainly Hydropsychidae), and lesser percentages of other aquatic arthropods. No observable effects on fish were detected. Populations of arthropods, especially amphipods, rapidly restored themselves after each treatment. During August 1967, both amphipods and gastropods were more abundant in treated than in untreated rapids. Residues of DDD were negligible and were expected to be relatively non-persistent. Occasional swarms of Trichoptera of relatively minor proportions, detected at the Expo 67 site by light traps, presumably arrived on steady southerly winds from the untreated Lachine Rapids more than 7 miles upriver. Information about the decomposition of DDD and related chlorinated hydrocarbons in nature is reviewed.

Pissodes fiskei, a species described by Hopkins from New Hampshire, is shown to occur also in Maine and in all Canadian provinces between New Brunswick and the interior of British Columbia, inclusive, as well as the Yukon. It is readily distinguished from its closest ally, P. lotundatus Lee, both morphologically and cytologically. Maritime P. nigrae Hopk., montane P. alascensis Hopk., and inland P. rotundatus are conspecific.

The oviposition behavior of Exenterus amictorius Panzer, an introduced parasite of pre-spinning eonymphs of the Swaine jack pine sawfly, Neodiprion swainei Middleton, was studied in a series of field experiments over a 5-year period in the Province of Quebec. The ability of this parasite to discriminate against hosts with previously deposited progeny varied significantly: discrimination was lacking at the beginning of the host’s spinning period, but was rapidly acquired and persisted to the end of the spinning period. The relationships were described by negative power functions of the form Iδ = aX−b, where Iδ = Morisita’s Index of Dispersion, and X = the number of days from the beginning of the host’s spinning period. The response of E. amictorius to changing host densities, however, was positive at all host densities and described by functions of the form Y = aXb, where Y = number of parasite progeny per host and X = number of hosts dropping into funnel traps at 2-day intervals during the spinning period. Over 67% of the variation in the number of progeny deposited by E. amictorius during a field experiment in 1969 was explained by changes in adult parasite density, and an additional 19% by changes in host numbers. This indicates strongly that the observed change in discrimination against previously deposited progeny bears no direct relationship to either host or parasite density. It was suggested that the change might be influenced either by a reduction in the parasite’s egg complement in time, or by an associative learning process.

The density response of an indigenous parasite, Exenterus diprionis Rohwer, was comparatively much weaker and it seemed to lack the adaptive changes in discrimination against previously deposited progeny possessed by E. amictorius. Although attacks of the one species occurred independently of the other, in the event of multiparasitism E. amictorius always survived because of its faster rate of development in the host. The role of discrimination and of density response in the dominance of E. amictorius among the Exenterus spp. attacking N. swainei, and its successful establishment on a variety of North American diprionids, is discussed.

Seventeen new species of Scolytidae from Mexico are described. The new species represent the genera Neodryocoetes (4), Pseudopityophthorus (9), Pityoborus (3), and Prognathotrichus n. gen. (1). New locality records for several previously described species are included.

Larval surveys were conducted in Winnipeg environs during the summers of 1967 and 1968. The species, density of larvae, the relationship between rainfall and larval abundance, and the species of pest importance were studied in detail. Aedes vexans was the most numerous mosquito found both in the larval and adult stages. Aedes dorsalis and Aedes spencerii were also of pest significance during each season. An association between the abundance of A. vexans larvae and the proximity of these to an adult blood source, mainly beef and dairy cattle, was observed.

The cereal leaf beetle, Oulema melanopus (L.), has rapidly increased its numbers and range since it was discovered in Michigan in 1962. We have shown in this report that intraspecific density-dependent mortality is the major constraint on survivorship. We have attempted to quantify survival within a generation from the egg stage to the adult.Larval mortality varies among populations. Density-dependent mortality, caused by intraspecific competition, accounts for most of the variation of within-generation survival of the cereal leaf beetle in wheat and oats. Mortality in the first instar on oats and the fourth instar on wheat and oats is a linear function of the logarithm of total egg density. Establishment of the first instar on oats appears to become more difficult as density increases because leaf surface disturbance and interference with larger larva increases. Competition for food accounts for the increase in mortality of the fourth instar in both wheat and oats as density increases. Egg survival, survival of the first instar on wheat and in the second, third, and pupal stage in both crops are constants with respect to density. These constants can be expected to change with respect to other environmental parameters however, e.g. host variety, planting date, rainfall, etc.

Acyrthosiphon pedicularis is described and illustrated and a key to the Canadian species of Acyrthosiphon is given.

The principal injurious species to commercially-grown flue-cured tobacco in Nova Scotia was the dark-sided cutworm, Euxoa messoria Harr. A trace of the black cutworm, Agrotis ipsilon Hufn., was found in one field. The variegated cutworm, Peridroma saucia Hbn., caused minor damage in September. Other species reared from field-collected larvae, and bait and light trap catches, included: yellow-headed cutworm, Apamea amputatrix Fitch; armyworm, Pseudaletia unipuncta Haw.; Amphipyra tragopoginis L.; W-marked cutworm, Spaelotis clandestina Harr.; and the glassy cutworm, Crymodes devastator Brace.

Cutworm larvae damaged young tobacco plants during June through mid-July. The largest infestation encountered during 1971, near the margin of a field, killed 5% and injured 20% of the young plants. Infestations in other fields injured 1 to 3% of the plants, with higher incidences near the borders. A seasonal total of 0.024 cutworm larva injured 0.24 tobacco plant/m2 and destroyed 5 to 10% of the injured plants in experimental tobacco field plots planted in a 4-year-old rye field.

Tobacco trap crop m2 microplots in a rye field attracted 20 to 50 times as many cutworm larvae and had 25 to 40 more plants injured than comparable areas of an adjoining tobacco field. The largest microplot infestation in six fields tested was 1.8 larvae injuring 7.4 plants. The average microplot infestation of 0.5 larva injured 5.6 plants.

Mature larvae and puparia of Compsobata univitta (Walker) found beneath a pile of decaying vegetation by a stream near Austin, Man., are described and compared with immatures of other Micropezidae.

The two subgenera and 20 species of the crab spider genus Ebo in North America north of Mexico are described or redescribed, keyed, and illustrated. The subgenus Ebo contains seven species, of which E. iviei, E. evansae, E. contrasts, and E. punctatus are described as new and the female of E. merkeli Schick is described for the first time. The subgenus Titanebo contains 13 species, of which E. cantralli is described as new and the female of E. texanus is described for the first time.

Seasonal and daily activity of three carpenter ants, Camponotus herculeanus, C. noveboracensis and C. pennsylvanicus in northwestern Ontario, was measured by counting the ants moving along underground trails. The start of seasonal activity was temperature dependent. Activity peaked in June and early July, corresponding to the period of rapid larval growth, and thereafter declined independently of temperature, ceasing in early October. Few ants (between 4 and 6%) carried visible objects. Daily activity was correlated with temperatures in early June, with the peak in mid-afternoon. However, as the season progressed activity extended further into the night, C. pennsylvanicus becoming virtually nocturnal. Temperatures inside the nest during larval development were raised as much as 16 °C above normal, presumably by metabolic heat from the ants.

Physiological interactions of n-saturated fatty acids, trans-2-unsaturated fatty acids and their methyl and ethyl esters with pre-imaginal stages of Aedes aegypti (L.) have been described. Differences in the response of the larvae and pupae to the same chemical and also the specific interactions of some chemicals synchronized with a short period during the development of a single stage have been emphasized. Investigations of a homologous series of fatty acids and their derivatives indicate that earlier statements to the effect that their toxicity increases as the series is ascended, and that maximum toxicity is reached in the vicinity of capric and lauric acids, should not be accepted without modifications.