The spatial distribution of egg clusters and cocoons of Neodiprion swainei and N. sertifer is described, and methods are developed for estimating the density of different stages on the same numerical basis.

Egg-cluster density varies directly with height in the tree, branch length, and tree size, evidently due to the females’ preference for illuminated sites. The overdispersion of egg-cluster counts reflects the heterogeneity of distribution of suitable oviposition sites rather than an inherent aggregative behaviour of parent females. Cocoon density within stands is not strongly related to the distance from the nearest tree, due to the wide dispersal of cocoon-spinning larvae. Some of the overdispersion of cocoon counts is due to differences in cocoon density between sections of a stand. Cocoons of males are more highly aggregated than those of females, and cocoons attacked by predators are more highly aggregated than ones not attacked.

The sampling unit selected for each life-history stage is one that permits density estimates of desired precision at minimum cost. In some stands, egg density can be estimated at minimum cost by direct counts per quadrat, in most stands, however, the whole tree is the most economical unit, despite the fact that per-tree density must be converted to absolute density in order to express all stages on a common basis. Sampling error can be reduced by stratification according to tree size. Gradients in cocoon density are seldom steep enough to permit stratification, but the cost of sampling can be minimized by adjusting unit size. Optimal unit size varies inversely with cocoon density and degree of aggregation, and is affected by soil type and the method used to extract cocoons.

The role of spatial distribution and sampling programs in studies of population dynamics is discussed.

The life histories and habits of four curculionids, Hylobius congener, Pissodes affinis, P. approximatus, and Magdalis perforatus, are outlined; and their role in relation to red pine plantations and a serious red pine mortality problem in the Algoma district of Ontario is discussed. A key to the adults is provided and control measures are recommended.

A key is provided to the larvae and pupae of three species of weevils, Pissodes approximatus Hopk., P. affinis Rand., and Hylobius congener D.T., common in red pine (Pinus resinosa Ait.) plantations in central Ontario.

The genus Reuteroscopus is known from North America, Central America, and the West Indies. Lygus uvidus Distant considered a synonym of ornatus Reuter is a good species and the name must be revived. Psallus nicholi Knight is transferred to Reuteroscopus. Descriptions are given for the following 11 new species, making a total of 16 known species for the genus: antennatus, aztecus, chillcotti, complexus, digitatus, mexicanus, and similis from Mexico; diffusus from Mexico, Costa Rico, and Panama; femoralis from Arizona and Mexico; curacaoensis from Curacao Is.; and hamatus from Florida, Mexico, Panama, Dominican Republic Puerto Rico, and Virgin Islands. Reuteroscopus sulphureus Reuter will be removed to another genus. Male genitalia of the 16 species are illustrated and a key to males is provided.

Three questions are asked in this paper.

(1) Is the numerical stability of an insect species through time a function of the number of species of food eaten by that species?

(2) Is the information content of a genus related to the stability of species in the genus?

(3) Is the information content of an insect genus related to the number of species of food eaten by the species in that genus?

Data in the Canadian Forest Insect Survey bulletins on Forest Macrolepidoptera are used to answer all three questions; data on parasitic Hymenoptera stored in museums are used to answer the third question. There is some indication that stability decreases with number of host species, and that information content of a genus is less, the less the stability of the species it contains. The evidence from both bodies of data suggests that information content of a genus is less, the greater the average number of species of food eaten by the species in the genus.

A spotted tentiform leaf miner, often present during recent years in large numbers in apple orchards in the Maritime Provinces of Canada, is identified as Lithocolletis blancardella Fabr., a species common on apples in Europe. Recent collecting indicates that the species occurs widely in Eastern Canada and the northeastern United States. Diagnostic characters, especially those of the male genitalia, are compared with those of specimens identified as L. crataegella Clem. and L. propinquinella Braun, two similar species which commonly occur on apple and black cherry respectively.

Laboratory experiments at various constant temperatures indicate a theoretical threshold of about 40°F. for spinning of cocoons by eonymphal larvae of Neodiprion swainei Midd. As temperatures fall below 52.5°F. the increase in mortality and time required to spin is pronounced. The optimum temperature is estimated to be around 60°F. Field investigations for three consecutive years show a close correlation between rate of spinning and temperature. Temperature is considered as a prime factor influencing the spinning of cocoons and is possibly one of the more important factors governing the population dynamics of N. swainei in the Province of Quebec.

Two new species of scale insects are described. These are the only scale insects known to occur in the Canadian Arctic. One is a species of Pulvinaria Targ. and one a species of Pseudococcus Westw.; both genera are known to occur in Greenland.

Insects caused serious damage to cones and seeds of white spruce during one of the five years of this study. A new seed and cone insect, Pegohylemyia sp., was recorded for the first time from Alaska. This insect destroyed an average of 50% of the seeds per cone.

In southern Alberta the range of Bombus (Alpinobombus) balteatus was limited to mountainous areas with minimum elevations of 7,400 ft. When given equal opportunity to nest in above- or underground hives, queens established in two above, and 12 underground hives. The middle of the nest-establishing period in the hives was about 24 June 1962, and 17 June 1963.

Construction of the brood cell was begun before that of the honey pot. All eggs of the first brood were deposited in n single cell; not all were deposited on the same day. Second- and third-brood egg cells were built in parallel lines on each side of the incubation groove. At least once, the second brood was also workers. Succeeding broods were probably first males and then queens, as males emerged first.

Pollen was fed collectively to worker larvae of all instars, except the last, by stuffing it beneath them. All instars of male and queen larvae, except the last, were fed collectively mixtures of honey and pollen. Last-instar larvae of all broods separated from each other by spinning flimsy, incomplete cocoons, and were fed individually mixtures of honey and pollen. Hence, B. balteatus is a pocket-maker when rearing worker larvae to the last instar and a pollen-storer when rearing last-instar worker, male, and queen larvae.

Bracon nuperus Cress. was reared from larvae of Orellia ruficauda (Fab.) collected at Vineland and Belleville, Ont., and Armstrong, B.C., by Dr. Peter Harris of the Research Institute, Belleville, Ont., while investigating the biological control of Canada thistle, Cirsiurn arvense (L.) Scop. (Harris, in press). The cocoon and cast skin of the last larval instar are described and illustrated here because the cephalic structures possess some unusual characteristics that differ from descriptions of this genus by other authors (Genieys 1925; Goidanich 193 1 ; Glover 1934; Salt 1931; Short 1952), and that have not been heretofore described. The methods and terminology used are similar to those described by Finlayson (1960).

In the spring of 1962 Caltha palustris was in bloom from April 30 to May 26. Thirty-nine species of insects in Cantharidae, Nitidulidae, Coccinellidae, Chrysomelidae, Cerambycidae, Miridae, Thripidae, Pieridae, Tenthredinidae, Apidae, Halictidae, Andrenidae, Formicidae, Sepsidae, Sciomyzidae, Ephydridae, Syrphidae, Anthomyiidae, Tachinidae and Muscidae visited the leaves and flowers. Many were found carrying pollen of the plant.

In the laboratory, the parasitic tachinids Drino bohemica Mesn. and Bessa harveyi (Tns.) made two to four times as many attacks on tenthredinid sawfly larvae exposed on unhealthy as on those on healthy food trees. Olfactory stimuli from the unhealthy trees were preferred by the parasites to those from healthy trees. The possibility of greater masking of stimuli from hosts on healthy foliage than from those on unhealthy foliage was apparently of little importance. In the field a moderate to severe attack by sawfly larvae on a tree will cause the tree to become unhealthy and this increases its attractiveness to the parasites. Thus, the host larvae indirectly assist the parasites to find them. Stimuli that are directly influenced by the health of the food plant of the host may interact with those from other environmental factors in determining the apparent degree of preference by tachinid parasites for different hosts.

The plastics and synthetic fibre materials used in insect traps may acquire and hold an electrical charge that could affect the efficiency of the traps. This became apparent while the Belleville rotary trap (Nicholls 1960) was being used to determine the influence of weather on insect numbers.

Over a period of a few weeks my colleague, Dr. J. A. Juillet, found that one net of the trap consistently caught more parasitic Hymenoptera (sometimes twice the number) than the other. Tests with an electrometer showed that the net of the trap that caught the lesser number of insects carried a negative electrical charge that created a potential difference with respect to ground of 40 volts at one centimetre from the net. Further observation revealed chat the charged net was set slightly higher than the other and that it struck a leaf of a nearby sapling as it rotated. The repeated brief contact was apparently sufficient to cause the net to be electrified. When the leaf was removed the charge on the net gradually dissipated and the numbers of insects caught in the two nets of the trap tended to be equal.

Colpocephalum ateri n. sp. is described from Daptrius ater and is differentiated from C. ceciliae Carriker from the same host species and from C. ibicter (Eichler) from D. americanus.