From March to October 1984, targets consisting of black cloth and netting, baited with l-octen-3-ol (released at about 0-5 mg/h), and acetone (about 100 mg/h) or butanone (15 mg/h), and coated with deltamethrin, were deployed at 3-5/km 2 in 600 km 2 of the Zambezi Valley of Zimbabwe where Glossina morsitans morsitans Westwood and G. pallidipes Austen were initially abundant. About 3 000000 adults of G. pallidipes and 200000 of G. m. morsitans originally present in the area as adults or pupae were killed by targets or removed by sampling procedures between March and December. At the end of this period, the tsetse populations in the centre of the block had declined by at least 99-99%. The targets dealt adequately with a strong invasion pressure from initially dense infestations nearby, partly because the targets reduced the abundance of tsetse up to 5-10 km outside the block. At 18 months after the start of the study, the targets were badly faded; this was corrected by spraying them with a black dye and an ultraviolet-light absorber that protected the dye and insecticide, but by then the targets had deteriorated and were without adequate odour attractant, and many were no longer being maintained. Tsetse then invaded further into the block, but only in small numbers. Tabanids and muscoids were not strongly attracted to targets; their population densities in and near the block did not change greatly. Targets offer a simple and ecologically clean method of controlling tsetse and preventing invasion.

An island of 4-5 km 2 in Lake Kariba, Zimbabwe, was stocked with cattle and infested with Glossina morsitans morsitans Westwood and G. pallidipes Austen in 1979. From February 1980 to April 1981, the tsetse populations, estimated by mark, release and recapture, increased about ten times, to contain about 3000 males of G. m. morsitans and 2000 males of G. pallidipes. From May 1981 to May 1983, six traps, with carbon dioxide and acetone as odour attractants, were used to capture 0-l-0-3% per day of the G. m. morsitans population and 1-A% per day of the G. pallidipes population. Captured flies were retained and killed, or were automatically sterilized with metepa and released. In May 1983, when the populations of G. m. morsitans and G. pallidipes had declined by about 90 and 99%, respectively, the traps were replaced by 20 targets with acetone and l-octen-3-ol as attractants. The targets were coated with dieldrin or, later, deltamethrin and killed about 2% per day of G. m. morsitans and 5% per day of G. pallidipes. Both populations then declined rapidly, G. pallidipes disappearing in 11 weeks and G. m. morsitans in nine months. Targets offer a cheap, simple and effective means of eliminating isolated populations of tsetse.

The wireworm survey in the Eastern Counties revealed many cases where the observed wireworm damage failed to correspond with the estimated field population. A possible explanation for this was the inaccuracy of counts made by picking wireworms out of the soil samples by hand. Tests showed that such methods recovered an extremely variable proportion of the wireworms in the‐ samples and, on the average, only two‐fifths of the larvae were obtained. A modified form of the washing and flotation technique used by Salt & Hollick (1944) was introduced for large‐scale work and is described. By this method, ten samples of soil (4 in. diam. and 6 in. deep) bulked together are examined at a time and can be dealt with at the rate of 13 samples per man per hour with an efficiency of 95‐100% in the extraction of wireworms. The populations estimated on 600 fields sampled between December 1942 and May 1943 have thrown more light on the size and composition of the wireworm population in grass and arable fields. Inspection of the crop results on fields tested by the washing process showed a much closer relationship between wireworm population and wireworm damage than had been obtained by the hand‐sorting method in the previous year.

PAGEthe influence of the magnetic field; the results of marking insects, and the inter-correlations between the British migrants. These are part of a thesis accepted by the University of London for the Degree of Ph.D.Miss M. E. Gibbs is author of the section on the records a t the British light vessels.J. A. Downes is author of the section on the migrations and reproductive cycle of D. plexippus in California, this being based on observations made during the tenure of a Commonwealth Fund Fellowship.The rest of the report is by C. B. Williams. The Bibliography (p. 264) contains a11 the references to the migration of Butterflies that we have been able to trace, and which are not in the Bibliography in Williams' book, including both older ones accidentally omitted from this and those published subsequently. Thus the bibliography in Williams' " Migration of Butterflies " (1930b) plus the Bibliography here is as complete a list as possible of the literature on the subject. 1752.According to Esper (1777, p. 136) Linnaeus is said to have recorded that Vanessa cardui wag very abundant at Upsala in Sweden in 1752. No reference is given and I have not been able to trace the original. Linnaeus refers briefly to the abundance in Faum Suecica (2) : 33, but this is later than Esper's reference. 1803.Haworth in his Lepidoptera Britannica (1803) p. 28, commenting on the appearance in England of Vanessa antiopa, writes : " There is something very extraordinary in the periodical but irregular appearance of this species, Papilio edusa (Colias hyale of this work) and Pap. cardui. They are plentiful all over the kingdom in some years, after which antiopa in particular will not be seen by anyone for eight, ten or more years, and then appears as plentifully as before. To suppose they come from-the Continent is an idle conjecture, because the English specimens [of antiopa] are easily distinguished from all others by the superior whiteness of their borders. Perhaps the eggs in this climate, like the seeds of some vegetable, may occasionally lie dormant for several years and not hatch until some extraordinary but undiscovered coincidence awakes them into active life." 1827.One of the earliest of records of butterfly migration in the tropics is by L. Guilding (1827), who writes : '' A species of Colias was lately sent to me from Trinidad, which was observed in a continued flight of thousands traversing that island from west to east. They were also observed a t sea in the neighbouring Gulf."The species was undoubtedly a Catopsilia (Phoebis) and probably P . statira, which I observed myself in large numbers migrating across Trinidad from east

Six grass fields were sampled once a fortnight from July 1943 to September 1944, and the wireworms in the samples counted by the washing and flotation method. The counts from twenty standard samples showed huge fluctuations which rendered them practically valueless as estimates of wireworm populations when treated singly. When treated as running means of four consecutive samplings, the counts showed certain seasonal trends, with minimum populations in July and August, rising populations throughout the autumn, maximum populations in the months from January to April and a sharp decline to the minimum populations again from April to July. On the average, the counts taken in winter were twice as high as those taken in the summer months. The fluctuation was evident in all size groups based on larval length but was most marked in the wireworms ‘under 4 mm.’, ‘4 mm.’ and ‘5 mm.’ Samples taken to depths of 12 and 24 in. showed that on the average about 75 % of the wireworms were found in the 0–6 in. layer and about 90% in the 0–12 in. layer. These proportions varied considerably with the seasons. The seasonal changes in wireworm populations observed do not correspond with those expected from the life history of Agriotes spp. Possible explanations for this anomaly are discussed, but it cannot be attributed to any known technical or biological factor. Several possibilities remain to be explored.