The lecanium scale was introduced into Vancouver with nursery stock from England in 1903, and by 1910 had become firmly established. Severe injury to broad-leaved maple, vine maple and horse chestnut was reported in 1923, and chemical control operations were undertaken from 1924 to 1930, but with very transitory effects (9, 10). The encyrtid wasp, Blastothrix sericea (Dalm.), imported from England in 1928 and 1929, quickly became established at the liberation points in Sorth Vancouver, and by June, 1930 had dispersed over an area of about 20 square miles. In April, 1931, twigs with parasitized scales from North Vancouver were distributed at intervals throughout the main area of lecanium infestation south and east of Vancouver, and by June of that year the parasite was known to be established over an area of about 100 square miles. By 1932, the percentage of parasitism in the mature lecanium females reached 90 to 100 per cent, and host population density was at very low levels (12, 13).

In the past twenty years or so many investigators have studied amplified electrical activity from nerve fibers supplving sensory receptors in many animals, including insects (see 2, 5, 8, 16, 19). With this technique much information has been secured concerning the characreristics of mechanical receptors (touch, pressure, sound, etc.) and photoreceptors. To a much lesser extent temperature, pain, taste and other chemical receptor activity in vertebrates has been studied although no electrical potentials appear to have been recorded from individual olfactory nerve fibers in any organism.

Shirtly after the appearance of my earlier paper (Munroe, 1951) on Chauliodes disjunctus, Prof. G. J. Spencer, of the University of British Columbia, wrote to me that he had two kinds of chauliodine males, one agreeing with what I described as the male of disjunctus, and another which he considered to be the true male of that species.