The red clover thrips, Haplothrips niger (Osb.), was first recorded from the state of Iowa and described by Osborn in 1883 under the name Phloeothrips nigra. The species hns since been collected and observed in many parts of the United States, southern Canada, and Europe. It wils reported in New England and recognized as a potential pest of red clover by Muggeridge (1933). Minute and very active, the adult insect is glossy black in contrast to the nymphal stages, which are bright red. In Minnesota, common host plants are alsike clover, Trifolium hybridum L., and red clover, T. pratense L.

It cannot be disputed that in any attempt to control populations of useful or harmful insects a knowledge of their ecology is of prime importance. In view of the significance of the various relationships between man and insects it follows that insect ecology should be a vigorous and strongly supported phase of entomology. It is the purpose of this discussion to consider briefly the present status of insect ecology and its relationship to ecology in general, and particularly to call attention to those characteristics of insect life that would seem to justify special treatment of insects from an ecological standpoint.

Occasions frequently arise in entomological work when it is necessary to handle large numbers of insect eggs. If the eggs are to be counted or treated, it is often necessary that they be held in a fixed position. A technique has been devised at the Ottawa laboratory by which many eggs can be handled and held with great ease. The eggs to be treated are placed on a sheet of Saran Wrap (Dow Chemical Company, Midland, Mich.). The static charge on the plastic is strong ennugh to hold the eggs securely. After treatment the eggs can be removed by means of a moist brush. This method is ideal for topical application studies and, if the Saran Wrap is backed with aluminum foil, it may be used to make excellent micro weighing dishes with adhesive qualities.

The eye-spotted bud moth, Spilonota ocellana (D. & S.), has a long history as a pest in Nova Scotia apple orchards, serious damage by it being reported as early as 1891 (Fletcher, 1892). Its status has fluctuated considerably, the most notable outbreak reaching its peak in 1927. This outbreak occurred when dusts were being used for the control of orchard pests, and (Kelsall 1932) was one of the two main reasons for abandoning the general use of dusts after 1927. The bud moth declined rapidly after 1927 and by 1931 was rated a minor pest (Gilliatt, 1932a). After flutuating at relatively low levels for seven years, it increased in importance and by 1942 was again a major pest. From 1942 to 1952, there was little change in its general status although large fluctuations in population were observed in orchards in which certain insecticides had been used (Stultz, 1950). During 1953, there was a marked decline in the average population level although reductions did not occur in all orchards.

The greatest predatory effect of small mammals is exerted upon insects that spend a portion of their life cycle on the ground or in the soil. Sawflies afford ample opportunity for mammalian predation, since they drop to the ground as mature larvae and spin cocoons in the soil. Such sawflies as Neodiprion abietis Harr., which remain within the cocoon for about three weeks, undergo only moderate risk of being preyed upon by small mammal. However, Pristiphora erichsonii (Htg.) remains within the cocoon from about mid-August until the following June, or even over more than one year, thus greatly extending the vulnerable period. Earlier investigations suggest that small mammals may comprise the largest single biological control agent acting against this insect (Graham 1928, Lejeune 1951), but the exact role of mammalian predators of forest insects has yet to be established.

On February 13, 1954 a heavy infestation of small galls was noted on a growth of willow shrubs (Salix sp.) in London Township about a mile north of London, Ontario. The exact location was on the north bank of the North Branch of the Thames River about 100 yards west of the bridge by which Adelaide Street crosses the river. The bushes were crowded along the bank and several of them had their lower branches under water and their roots extending well out into the mud of the river. The galls were one-eighth to three-eighths of an inch long (Fig. 1) and were roughly spherical to oval in shape. The bark of a gall was scarred by shallow furrows running along its length. At its upper end each gall bore the scales of a withered bud or an oval scar from which the scales had fallen. Flanking the scar were two rounded swellings of incipient buds. Many of the galls were separatelv developed along the twigs, being well apart from one another, hut in some cases they were crowded against one another so that three or four galls occupied one inch of the length of the twig, and in several instances a number of adjacent galls had coalesced to form an irregular swelling one or two inches long, along the length of a twig. In the key to insect galls of willow in Felt (1940) the galls were identified as scarred willow galls caused by the gall fly Phytophaga tumidosae (Felt).

Although a virus disease of the larch sawfly, Pristiphora erichsonii (Htg.), has not been discovered, polyhedrosis viruses of several other Tenthredinids are known. They have been used to control infestations of two introduced species: the European spruce sawfly, Diprion hercyniae (Htg.), (Bird, 1954) and the European pine sawfly, Neodiprion sertifer (Geoffr.), (Bird, 1950, 1952, 1953; Dowden, 1953). Unfortunately, the viruses of these, as well as the viruses of several other species tested, are not pathogenic to the larch sawfly. Some viruses, however, appear to he pathogenic to more than one species. J. M. Burk of this laboratory found, for example, that a polyhedrosis virus affecting the native jackpine sawfly, Neudiprion americanus banksianae Roh., is pathogenic to N. sertifer, N. nanulus Schedl, and D. hercyniae.

Cabbage and related crops are attacked every year throughout Ontario by caterpillars of three species, namely, the imported cabbageworm, Pieris rapae (L.), the diamondback moth, Plutella maculipennis (Curt.), and the cabbage looper, Trichoplusia ni (Hbn.). The imported cabbageworm is generally regarded as the most abundant of the three species and is reported as doing damage of considerable economic importance each year. The cabbage looper does not occur in large numbers until late in the season, but in most years it is believed to be second only in importance to the imported cabbageworm. The diamondback moth is generally considered to be much less important than the other two species (Caesar, 19i8). As previously reported (Matthewman et al., 1952), these beliefs were not borne our by observations of field populations at Ottawa in 1950. Whereas populations of the cabbage looper were strikingly low, those of the diamondback moth were much higher than the literature indicated. This paper is a summary of four seasons' experiments, 1951-1954, undertaken to assess the abundance and relative importance of the three species in eastern Ontario.

During studies of the parasite complex of the spruce budworm in the Lake Nipigon region of northern Ontario from 1946 to 1950, data were obtained on certain host-parasite relationships. The data were derived from two sources: the rearing each year of periodic collections of spruce budworms, and the dissection of budworm larvae and pupae that were collected and preserved at 2-day intervals during June of 1948 and 1949. The particular features investigated were: the sex ratio of parasites and its possible relation to the sex of the host; and the effect of parasitism on the apparent sex, rate of development, and size of the host.

The life histories of many of the Geometridae are not well known; those of a few economic species in the Ennominae have been worked out but many more remain to be studied. Life-history notes on the following seven species are presented: Semiothisa granitata Gn., S. sexmaculata Pack., Eufidonia discospilata Wlk., Melanolophia canadaria Gn., Campaea perlata Gn., Selenia alciphearia Wlk., and Caripeta divisata Wlk. The larvae of all these have been described; those of Selenia and Campaea were described by Dyar (1899 and 1903) and the remainder by McGuffin (1943a, 1943b, 1944, 1945, and 1947).

Craighead (1923) described the larvae of four North American species of Acunthocinus and constructed a key for their separation; two of these, A. nodosus (Fab.) and A. obsoletus (Oliv.), occur in the eastern half of the continent. During recent studies of cerambycids infesting fire-killed pine in central Ontario, another species, A. pusillus Kby., was encountered in large numbers, but the larvae could not be identified because of the lack of a published larval description. Larvae were eventually reared from known parent adults, and, since wood-boring Coleoptera are most frequently encountered in immature stages, the following description has been prepared.

Severe local infestations of a cottony scale on peach have been reported from the Niagara district of Ontario since the early 1920's. The species has been commonly referred to the cottony peach scale, Pulvinaria amygdali Ckll., but Steinweden (1946) showed that amygdali was an entirely different species, leaving the identity of the local species on peach in doubt.

Dryness of either an insect's habitat or its food has often been reported as inducing diapause. This has been well substantiated in Pectinophora (8, 21, 22) and Loxostege (23). Also, a difference in body moisture between forms of the same species, in diapause and not in diapause, has been recorded in Leptinotarsa (9), Lucilia (11), and Carpocapsa (24), there being less water in the insects in diapause. It is significant, though, that in preparing for diapause Leptinotarsa achieves a reduction in moisture content, even when there is an abundance of water outside, by excretion (4).

For many years, the black fly Simulium venustum Say has been considered to be the chief vector of Leucocytozoon simondi M. & L. (=L. anatis Wick.), a protozoan parasite infesting the bloodstream of ducks and geese and causing a malarialike disease that is usually fatal to immature birds. The organism undergoes part of its life-cycle in the stomach of the fly, which transmits it, through its bite, to the primary host. Its development in the latter results in the rupture of blood cells, with extensive destruction of tissue of the spleen, liver, and other organs. Although, superficially, the case against S. venustum appears to be already proved, recent studies of this species in Eastern Canada have indicated that some aspects of its supposed relation to L. simondi cannot readily be explained on the basis of what is known of its life-history and habits. My attention was focussed on this problem when I discovered in 1953 that the Simulium species reported by Walker (1927) as causing wholesale deaths in a flock of goslings at Fredericton, N.B., was neither Simulium bracteatum Coq. (a synonym of S. (Eusimulium) aureum Fries), as reported by Walker, nor S. venustum Say, as suggested by Twinn (1933).

Among the many insects under investigation as potential vectors of the oak wilt fungus in Wisconsin and elsewhere, the species of Pseudopityophthorus have attracted considerable attention. Although recent developments appear to indicate that the long-distance spread of this serious disease occurs primarily with the aid of other insects, our knowledge at present does not warrant the assumption that bark beetles play no part whatever. In the study of P. minutissimus from August, 1952, to the fall of 1953, considerable information concerning its biology in Wisconsin has been brought to light; and regardless of its relationship to the oak wilt problem it seems desirable at this time to make better known this member of the Wisconsin bark beetle fauna.

Fungi and bacteria each play a role in the natural control of many sawflies, including P. erichsonii. Parasitic fungi, for example, have been isolated from species in the following genera: Anoplonyx, Arge, Monoctenus, Neodiprion, Trichiosoma, Hemichroa, Pikonema, and Pristiphora. The isolates include species from Cephalosporium, Sorosporella, Isaria, Beauveria, Spicaria, Hirsutella, and Empusa (MacLeod, unpub.). The last five fungus genera have been isolated from larch sawfly collections made in various parts of Canada and the United States.

From 1952 to 1955 the author has been engaged in a study of the predacious mites of importance in controlling the European red mite, Metatetranychus ulmi (Koch), in southern England. During this time an opportunity was afforded to become familiar with many of the species in the genus Typhlodromus that are thought to be of some value in this regard (Gilliart, 1935; Nesbirt, 1951; Collyer, 1953).

Wilted stems of Eupatorium odoratum L., (Compositae) in Trinidad were found to contain an egg or lama of a Curculionid. Each egg was deposited in a slit between two rows of punctures encircling the stem. This girdling made by the ovipositing female was obviously the cause of the wilting. Larvae hatching from the eggs fed for a few days ih the wilted portion of the stem and then tunnelled into the sound tissue below the punctures completing development a month later, and pupating in the stem near the base of the plant. The adults, which emerged ten days later, were identified as Rhodobaenus sp. nr. cariniventris by Mr. R. E. Warner of the U.S. National Museum.

The importance of predators in the natural control of mosquitoes has been suggested by a number of workers. Comprehensive reviews have been presented by Hinman (1934) and Gerberich (1946). The conclusions are open to some question, however, since the investigations were confined for the most part to studies in laboratory aquaria. These environments create conditions such as crowding, absence of prey shelter, and lack of alternative prey, which prevent an analysis of predation in terms of field conditions. An accurate assessment of predation in nature requires a technique to identify predators that have consumed prey. This is a report on an attempt to analyse the predator-prey relationships of animals in a natural mosquito pool in a woodland swamp near Chatterton, in Hastings County, Ontario, in April and May, 1953, by means of a radioactive tracer.