In an earlier study (Holling, 1959) the basic and subsidiary components of predation were demonstrated in a predator-prey situation involving the predation of sawfly cocoons by small mammals. One of the basic components, termed the functional response, was a response of the consumption of prey by individual predators to changes of prey density, and it appeared to be at least theoretically important in population regulation: Because of this importance the functional response has been further examined in an attempt to explain its characteristics.

Whilst we were examining a large number of Acridoidea in connection with current morphological studies, an interesting specimen of Eyprepocnemis plorans ornatipes (Walker) came to our notice. The specimen, a female with three compound eyes, was discovered among many normal examples of the same species kindly provided for study from stock reared under artificial conditions at the Anti-Locust Research Centre, London, England.

In a number of the systematic studies of caddisflies with which I have been concerned, it has been necessary to rear larvae to the adult stage in the laboratory. Several methods proposed for rearing aquatic insects were considered, but these seemed open to some improvement, mainly because, for my purpose, it was necessary to rear large numbers of larvae in individual containers. For this reason the rearing equipment described here was designed. The principal advantage gained through its use is that relatively little maintenance is required to achieve fairly constant rearing conditions for large numbers of larvae, with each larva in a separate cage. By combining a number of individual cages into a unit, with its own supply of water and compressed air, attention to the needs of each individual cage is reduced considerably. By adding additional units, the capacity of the equipment can be doubled or trebled, while the corresponding increase in the maintenance requirements is proportionately much lower. In addition to providing an efficient means of rearing larvae in the laboratory, the same equipment can be used in the field under various conditions. Although caddisflies have been the only insects reared up to now, it is altogether likely that similar equipment would be suitable for other aquatic groups as well.

Female. Frons slightly produced, with a rudimentary median carina. Head, body and forewing above pale luteous, hind wing above and under side whitish. Abdomen above with narrow white basal band and with three or four obscure blackish-powdered mid-dorsal spots. Fore coxa, femur and tibia brown anteriorly. Forewing above with narrow, obscure, dark, irregularly dentate ante- and post-medial lines. Antemedial oblique outward to origin of Cu1, then sharply angled and oblique inward to inner margin. Postmedial nearly parallel to outer margin, weakly indented along submedian fold. An hourglass-shaped mark at the end of the cell. All these markings surrounded by faint fulvous clouding. Outer margin with minute black dots at ends of veins. Fringe concolorous. Hind wing with one or two dark dots in submedian fold and with black terminal dots at the veins. Under side of forewing with lunate discocellular mark and anterior half of postmedial line conspicuously dark.

During the winter of 1957-58 larvae of the tent caterpilIars Malacosoma pluviale (Dyar) and M. americanum (F;.) were reared to provide material for tests on the spore-forming bacterium reported by Bucher (1957). AS there is little published information on winter rearing of sent caterpillars, except that of Sippell (1952) on M. disstria Hbn., the technique is given below.

Scolytus tsugae (Swaine) is a bark beetle that occurs throughout the Pacific Coast and Rocky Mountain Region and is common in the interior of British Columbia. Although Bedard (1938) reported that it had killed small areas of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) reproduction, it is of minor economic importance and usually confines its attack to tops, limbs, and logging slash. A knowledge of the life-history and habits of this insect is desirable for an understanding of the effects of interspecific competition on the development of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopk., with which it is often associated in Douglas fir.

At Ottawa, during studies on the parasites of the armyworm, Pseudaletia unipuncta (Haw.), in 1955, 1957, and 1958, 20 species of Hymenoptera were reared from larvae or pupae of the armyworm collected from fields in the area during July and August. Of the 15 species thus far identified, 12 were primary parasites; four of these, namely, Euplectrus mellipes Prov. (Eulophidae), Hyposoter annulipes (Cress.) (Ichneumonidae), Microgaster auripes Prov. (Braconidae), and Therion sassacus Vier. (Ichneumonidae), have not been previously recorded as parasites of P. unipuncta.

In July, 1956, studies on mortality factors affecting abundance of immature stages of the eye-spotted bud moth, Spilonota ocellana (D. & S.), and the pistol casebearer, Coleophora serratella (L.), on apple were initiated in permanent orchard plots at Rougemont, Que. The object was to prepare life tables (Morris and Miller, 1954) for successive generations of each species through the rise and fall of a local epidemic. In preparing such tables, sound sampling techniques are necessary (Morris, 1955). This is a report on variation in samples, and in some mortality factors, of immature stages of the two species for the years 1956 to 1959, and on sampling recommendations.

Because black flies are active for only a few months each year in the vicinity of this laboratory, methods for collecting, extracting, sterilizing, and storing eggs were devised to facilitate a year around program of research. These methods were developed partly from existing entomological and limnological techniques.

Aphids of the species herein described as new can be readily distinguished from all other species in the genus Cinara by the unusual length of the unguis. The feeding site is also characteristic; this is the only species in the genus known to feed on the roots of Pinus banksiana.

The species was first collected in 1956 at Lac La Ronge, Saskatchewan, by B. B. McLeod, of the Winnipeg Laboratory. In 1957 it was found by the authors at Cedar Lake, thirty miles north of Vermilion Bay, Ontario, where observations on the life history of the species were carried out.