Eighty Engelmann spruce logs (Picea engelmannii Parry), which were distributed in open (bulldozed to clearcut), semi-open (selectively cut), and dense (uncut) spruce forest, were infested with Dendroctonus obesus (Mann.) and Ips pilifrons Sw. and fed upon by northern three-toed and hairy woodpeckers. Sections of the infested boles were covered with screen to prevent woodpecker feeding and all logs were left in the field over one winter and through the following summer. By spring, the spruce beetle brood was reduced approximately 50% in all three forest areas. By fall, the spruce beetle brood suffered a 71, 83 and 52% reduction in the open, semi-open and dense forest, respectively. Spruce beetles appeared to be in greatest numbers in the semi-open forest, resulting in the greatest woodpecker predation there. Woodpeckers did not feed in the open meadows. Estimates in the spring, before the Ips emerged from the logs, showed that woodpeckers reduced the Ips brood by 76 and 11% in the open and semi-open forest, respectively. Ips were not found in dense forest or in meadows.

Random counts of the white grubs, Phyllophaga fusca Froelich and P. anxia LeConte, in a permanent meadow did not conform to the Poisson distribution, there being an excess of uninfested and highly infested sample units over the expected number. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. Using a common k, the distribution of the various stages may be described by expansion of (q-p)−k, when values of k are as follows: egg 0.15, first instar 0.41, second instar 1.30, third instar 2.00, pupa 1.62, teneral adult 1.30. Aggregation resulted from the clumping of eggs at oviposition, and randomness increased with dispersal of the larvae. For all stages, the variance was proportional to a fractional power of the mean. Three transformations are offered for stabilizing the variance of field counts.

A review and analysis of the literature showed that precipitation, or its absence, can regulate the numbers of or the damage by insect pests of annual crops in Canada in essentially four main ways: as soil moisture, when the insects are in the ground; as a mechanical factor that impinges directly on them when they are exposed; through its effects on foodplants; and through its effects on natural enemies of the pests. Though any one pest species may be influenced by two or more of these processes and in different ways by each depending on the stage of its life cycle that is affected, usually only one way is significant. Precipitation is so far of little value in forecasting pest situations reliably, but water in various forms has much potential for use as a pest control agent.

Larvae of Enoclerus sphegeus Fabricius (Coleoptera: Cleridae) were separated into three groups for study. Throughout their development, the larvae in each group were fed mountain pine beetle larvae, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), of a specific size (small, medium, or large). Clerid larvae fed small D. ponderosae larvae generally completed three stadia, while the other two groups, which were fed medium-sized and large prey, respectively, usually passed through two larval stadia. The number of stadia a larva would have was determined by the amount of food consumed during the first stadium. The feeding period of larvae given small prey was considerably longer than that of those fed medium-sized or large beetle larvae, but the prepupal period was much shorter. The head capsules of second-instar larvae that passed through two stadia were distinctly wider than those of second-instar larvae that completed three stadia.

A telemetric system for the measurement of bark temperature of standing trees was developed and compared with a conventional thermocouple system. The components of the system and circuit diagrams are given. The cost of a single unit was about $65. The system was field-tested under both summer and winter conditions in the Sierra Nevada mountains of California. It was concluded that the telemetry system gave more accurate temperature readings and that it possessed several other advantages over the conventional system. While the system was developed for the measurement of temperature, it could be used for the measurement of any environmental variable for which there is a variable-resistance transducer.

The generic limits of Paragnorimus Becker are redefined and two new species, P. sambucus from Chiapas, Mexico, and P. guatemalensis from Volcan Acatenango, Guatemala, are described.

Campylomma verbasci (Meyer) overwinters as an egg on apple, pear, Rosa spp., and Amelanchier sp. On pear, the chief prey are eggs and nymphs of Psylla pyricola Forster and all stages of Panonychus ulmi (Koch). C. verbasci is partially phytophagous but prolonged feeding by nymphs on pear fruits caused no injury. During the summer, C. verbasci lives and reproduces as a predator–phytophage on a number of herbaceous plants. Three, possibly four, generations occur in the southern interior of British Columbia. The effects on C. verbasci populations of a number of pesticides applied to pear trees are reported.

Eight species of insects parasitic on the Oriental fruit moth, Grapholitha molesta (Busck), were reared from host larvae collected in a peach orchard that was unsprayed since 1962. Macrocentrus ancylivorus Rohwer was the dominant species and parasitized between 40 and 50% of first and second generation larvae from 1964 to 1966. Despite this the parasite did not appear to be a controlling factor in these years and population fluctuations of the fruit moth resulted from other causes. In 1967 parasitism rose sharply to 61% in the first generation and 74% in the second. Low adult emergence in the second generation was related directly to the increased parasitism. Effectiveness of the parasite depended both on its numbers and degree of synchronization with the development of the moth population. To determine its total effect parasitism must be measured throughout each generation of the fruit moth, because in most years it tended to reach a maximum early in the generation and then gradually decline.

Ips integer (Eichhoff) is removed from synonymy with plastographus (Leconte), which in turn is divided into two subspecies: p. plastographus (Leconte) and p. maritimus n. subsp. The former occurs in the subalpine zone of the Sierra Nevada, Cascade, and northern Rocky Mountain ranges; the latter is apparently restricted to the California coast.I. integer and p. plastographus are partially sympatric, but even in a mixed attack on the same host the two species were rarely found in the same gallery systems. In field experiments females showed strong preference for the sex pheromone of conspecific males. Laboratory-produced hybrid males were intermediately attractive to both species.In breeding experiments the plastographus subspecies were fully interfertile but fertility of backcross and F2 generations was reduced. Egg hatchability was low in interspecific combinations of integer and plastographus. However, results were different for the reciprocal pairings and the backcrosses showed increased fertility. These data defy explanation by nuclear genetics but may result from cytoplasmic incompatibility.Although integer and the two plastographus subspecies have the same karyotypic formula, 15 A A + Xyp, the three entities can be differentiated by the size of heteropycnotic segments in pachytene chromosomes and the shapes (centromere position) of some of the five largest chromosomes at second metaphase. Univalents, multivalents, bridged anaphases, and other abnormalities were common in hybrids of plastographus and integer. Heteromorphic bivalents, but no other abnormalities, were observed in hybrids of the plastographus subspecies.

Varying degrees of ovarian development were induced in overwintered Dendroctonus pseudotsugae Hopk., put on (1) host logs, (2) bark chips, or (3) moist glass paper. In 96 hours the ovaries of beetles on logs reached maturation, those on bark chips showed only slight growth, and the third group failed to show any development.Farnesyl methyl ether induced significant ovarian development in beetles kept on bark chips or glass paper. It appears that production or release of gonadotrophic hormone is withheld in insects kept outside their natural gallery environment. Sensory input associated with gallery excavation may initiate ovary development by stimulating endocrine activity.

Species of the North American genus Platylygus Van Duzee 1915 are revised. Redescriptions are given for 5 previously known species, and 26 new species are described. Nineteen species described by Kelton are: angulatus, brevirostris, longirostris, and mexicanus from Durango, Mex.; aztecus from Mexico, Mex.; chamulans and chiapasensis from Chiapas, Mex.; alpinus from Chiapas, Mexico, and Puebla, Mex.; crassicornis from Mexico and Puebla, Mex.; pilosus and teocotae from Mexico, Mex.; pilosipes from Durango, Mex., and Arizona; scutellatus from Durango, Mex., Arizona, and New Mexico; contortae, crinitus, and magnus from California; knighti from Arizona and Colorado; piceicola from British Columbia, Yukon Territory, Arizona, and Colorado; pseudotsugae from British Columbia and Oregon. Seven species described by Knight are: keltoni from Durango, Mex.; andrei from Arizona; balli from Arizona, Colorado, and New Mexico; hirtus from Arizona; rolfsi from British Columbia, California, Oregon, and Washington; rubripes from Alberta, British Columbia, California, Colorado, Oregon, and Wyoming; and usingeri from California. The other species in the genus are: fuliginosus Knight from Arizona; grandis Knight from Arizona, California, and Colorado, Montana, and South Dakota; intermedius Knight from Arizona, Colorado and New Mexico; luridus (Reuter) from Alberta, British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan, Yukon Territory, Arizona, Colorado, Illinois, New Hampshire, New Mexico, New York, and Wyoming; and vanduzeei Usinger from Arizona, California, Colorado, New Mexico, Nevada, and Utah. Platylygus uhleri (Van Duzee) is considered to be a synonym of P. luridus (Reuter). A key to species, records on distribution and biological data are included, and the male genitalia of all but one species are illustrated.

Some aspects of the biology of the Tabanidae (e.g., seasonal distribution, relative abundance, habitat preferences, and innate host preferences) which influence the extent to which certain species are found biting various host species are discussed in relation to the tabanid population of the southern portion of Algonquin Park, Ont., Canada. Of the 36 species collected in this study, relatively few were sufficiently abundant to constitute serious pest problems.The analysis of collections of tabanids from carbon dioxide-baited traps placed in different habitat types revealed several patterns of distribution of the Algonquin Tabanidae: ubiquitous, exclusively sylvan, preferentially sylvan, riverine, and riparian species.Lists of the tabanids attracted to or biting man, moose, and white-tailed deer are presented. These lists constitute the first extensive records of the Tabanidae attracted to the Cervidae in the boreal forest region of Canada.The Chrysopinae selected smaller hosts than the Tabaninae and were severe pests of man whereas the Tabaninae were only minor pests of man but severe pests of moose. The tabanids attracted to deer presented a picture which was intermediate between that of man and moose. In addition, a few species of tabanids were unusually common on one or more hosts suggesting that some species may have innate preferences for certain hosts.

Laboratory experiments indicate a diet of quaking aspen is essential to give impetus to a population increase of the large aspen tortrix. The effects of starvation and of five different host plants on larval survival, pupal weights, and adult egg potential are reported.

Basilia andersoni n. sp. and B. plaumanni Scott represent the first species of Nycteribiidae to be reported from Uruguay. B. andersoni was found on Myotis nigricans (Schinz), and is closely related to B. guimaraesi Sch. Stekh. and B. currani Guim. It is characterized mainly by the shape of the thoracic sternal plate and legs of both sexes, tergal plates I and II and sternite VI of the female, and the aedeagus of the male, as well as by the chaetotaxy of the legs, tergites and sternites of both sexes, and of the anal segment, genital and anal plates of the female.