Leaf-miners associated with common cultivated plants are especially liable to become esrahlished in new areas through transportation with their hosts, and this possibility should always be considered when the agrommyzids of poorly-known faunal regions are studied, so that redescription of such species as new forms may he avoided. One of the species here recorded for thc first time from both Chile and Easter Island is a case in point. Phytobia maculosa (Malloch), known as a leaf-miner in cultivated Chrysanthemum in the U.S.A. since 1896 (though not correctly recognized and described until 1913), has since been redescribed from the same host plant in southern Brazil. Its known hosts now include 13 genera of Compositae and it is evidently widespread in the U.S.A., in the West Indies, and in temperate South America. It also occurs in Hawaii. Although not so far reported in Canada it almost certainly will be found in southern Ontario and British Columbia. Horticulture, both private and commercial, must have greatly assisted its spread in North America and elsewhere.

Two strains of the pupal ectoparasite Nasonia vitripennis (Walk.) originally derived from a single laboratory strain exhibited differences in the proportion of adjacent hosts attacked by the parasite following 65 weeks (approximately 32 generations) in experimental parasite–host systems. Strain I parasitized a greater number of adjacent hosts (19.9%) than strain II in the first generation after removal from the multi-cell system. The difference between the two strains and the laboratory strain decreased from the first to the fourth generation indicating a reversion toward a behavior pattern more akin to that of the laboratory strain.

Volume 99, 1967

Page 447, first two lines, for Jerry A. Mackie read Jerry A. Powell and Richard A. Mackie.

Pineus floccus Patch is an occasional pest of ornamental spruces in eastern North America which produces unsightly galls at branch extremities. Damage to the specific alternate host, eastern white pine (Pinus strobus L.), may result in lateral shoot injury similar to that reported for P. pinifoliae (Fitch) by DeBoo, Dimond, and Lowe (1964). However, outbreaks of P. floccus are uncommon, with populations regulated at low levels throughout most of its distribution.

A new species of leafhopper, Draeculacephala robinsoni, very similar to D. portola Ball, has been examined and found to be distinct from that species, on the bases of internal male genitalia and vertex angle.

The cage and pot described here were used successfully in extensive studies on the transmission of aster yellows virus by the six spotted leafhopper, Macrosteles fascifrons (Stål) (Richardson 1966). The use of this composite unit results in a saving of labour, cost, and greenhouse space.

The materials for the testing unit consist of a round peat pot, 3 in. in diameter and 3 in. deep, and a 1-lb polyethylene bag approximately 8 in. long, with an opening 3 in. in diameter. The seedling growing in the pot is covered by the inverted bag and the mouth of the bag is then pulled down over the rim of the pot and secured with a rubber band (Fig. 1). Several hundred small holes are made in the bag to permit air exchange.

Ecological studies, undertaken to determine the fluctuations of phytophagous mites and predators in apple orchards, were conducted in 1955, 1956, and 1957 at Rougemont, Que., in two plots sprayed only with fungicides for the control of apple scab, Venturia inaequalis (Cke) Wint., and in a third one sprayed, in addition to fungicides, with all insecticides needed for the control of destructive insects. Phytophagous mites were more numerous in the plot sprayed with insecticides than in plots sprayed only with fungicides, and densities of the mites in the latter plots were inversely proportional to densities of predators. A similar relationship existed in the insecticide plot between the amount of chemicals used and numbers of predators present. The principal mite predators were Typhlodromus rhenanus (Oudms.), most effective against the two-spotted spider mite, Tetranychus urticae Koch, and Mediolata mali (Ewing), most effective against the European red mite, Panonychus ulmi (Koch).