Mites or Acari belong to the class Arachnoidea, which also contains the Scorpions, the Spiders, the minute False-Scorpions, the long-legged Field Spiders and some other curious eight-legged creatures. They are at present considered as a degenerating branch of the Arachnoid trunk. Their larvse are six-legged, their nymphs eight-legged, but deprived of genital apertures.

Apart from the Ticks (Ixodoidea), mites have been generally very much neglected by collectors and systematists alike; but seeing that they comprise a considerable number of species of undoubted economic importance, it has seemed desirable to call attention to them by this brief account of some of the more striking forms. A fuller investigation of their habits and lifehistories, especially as regards tropical species, is certain to yield much information that is likely to be of both practical value and scientific interest.

The biology of Rhyssa persuasoria, L., and of Ibalia leucospoides, Hochenw., has already been sketched in a preliminary paper published in this Bulletin (xix, pp. 67–77, pl. iii, 1928) in collaboration with Mr. R. N. Chrystal, of the Imperial Forestry Institute. The following observations were made by the writer chiefly at the Farnham House Laboratory, during the spring and summer of 1928, and are gathered together in view of his departure from England. The work of collecting and rearing supplies of Rhyssa and Ibalia for shipment to New Zealand, for the biological control of Sirex nodilio (juvencus), has been continued on a larger scale. The present notes were made incidentally during this work and are arranged under nearly the same headings as in the previous paper, to which they are supplementary. One error needs correcting. It was stated (on p. 75) that the larch (Larix europaea, D.C.) is indigenous, though actually planted in the Oxford locality mentioned. As a matter of fact, of course, larch, though Palaearctic, is not indigenous to Britain.

Epidinocarsis lopezi (De Santis) was found to parasitize and complete development in all developmental instars of its host, Phenacoccus manihoti Matile-Ferrero. However, parasitoid mortality was high (15·8%) when development took place in the first nymphal instar of the host. Complete development from egg to adult emergence was prolonged in smaller hosts, and developmental periods recorded were 18·8, 17·4, 16·1 and 14·9 days for the first, second, third and fourth nymphal instars, respectively. Irrespective of the age of the host parasitized (with which size is strongly correlated), E. lopezi completed only one life-cycle during one life-cycle of P. manihoti. Oviposition commenced within 24 h of emergence and lasted effectively for six days, during which 95% of its eggs were laid and 10·8 large hosts were killed through host feeding. Unmated females of E. lopezi are arrhenotokous, laying only male eggs; eggs laid by mated females produced males and females in the ratio of 1:3 in favour of females.

Field studies in Zimbabwe elucidated the responses of Glossina morsitans morsitans Westwood and G. pallidipes Austen to natural and artificial trunks of trees baited with odours of acetone, 1-octen-3-ol and phenols. The numbers of tsetse electrocuted in flight near the base of the trunk increased 2–12 times when the trunk was shortened from 7.2 m to 0.9 m and its diameter was increased from 25 cm to 5 m, when the base was coloured blue or black to contrast with the upper trunk, or when the upper trunk was separated from the base by a gap of 2.7 m. A swarm flying near short trunks was more compact than near tall trunks. Electrocuting grids to catch alighting tsetse indicated that only about 20% of the attracted tsetse alighted on the base of the trunk, whether this was blue or blue/black. Since there is presently no apparent means of cost-effectively avoiding the inhibitory effects of tall trunks, the use of odour-baited trees as baits for tsetse control seems uneconomical.

The different instars of Agriotes sputator larvae cannot be distinguished by measurements of total length or of various parts of the wireworm.

The number of teeth on the mesothoracic and abdominal spiracles increases with age, and an examination of 700 wireworms showed that the average numbers of teeth on the two thoracic or on all the abdominal spiracles fell into eight groups. These criteria were valid for populations collected at different times of the year.

The number of teeth on the thoracic spiracles of a larva in any particular group approximates to that on the abdominal spiracles of a larva in the next larger group.

The eight groups formed by counting either the thoracic or the abdominal spiracle teeth represent growth stages and not necessarily instars.

The larvae may sometimes moult without growth, a phenomenon probably caused by an inadequate supply of food. At such an ecdysis the number of spiracle teeth does not increase.

The larvae pupate after attaining an optimum size, and reach this size in seven or eight growth stages.

A quick method of determining the growth stage to which a larva belongs is given, whereby more than 80 per cent, of the larvae are placed in their correct growth stages by counting the teeth on one spiracle only ; for less than 1 per cent, of the larvae is it necessary to examine as many as five spiracles ; an accuracy of more than 97 per cent, can be maintained.

The possibility of determining the relationship of growth stage and age is discussed.

The division of the larvae into those which will pupate after seven, and those which will pupate after eight growth stages is apparent at a very early stage in the life history. One larva was found which appeared to be in its ninth growth stage.

The cause of this difference in growth stage number is unknown. It may be due to the size of the egg, to the time of the year at which hatching occurs, or to heredity.

The genus Nysius, Dallas, as pointed out by China (1934), is in some respects the most cosmopolitan of all Hemipterous genera. Two species have been previously described from Australia, of which one, Nysius vinitor, Berg., occurs in every State of the Commonwealth. The other species, Nysius clevelandensis, Evans, is known only from Queensland. Below is described a third species which is apparently confined to Tasmania.

The productivity of Glossina palpalis palpalis (R.-D.) reared in vitro via silicone rubber membranes on fresh guinea-pig blood equalled the productivity of flies fed in vivo on guinea-pigs. Over 50 days, the number of puparia per initial female was 3·0 in both cases. Puparial weights were greater than 31 mg throughout the four reproductive cycles. While fresh blood was an excellent diet for G. p. palpalis, freeze-dried guinea-pig blood was unsuitable; survival, reproduction and puparial weights were all low for flies fed on freeze-dried blood. The evidence lends support to the theory that there is no inherent nutritional deficiency caused by feeding on blood through a membrane.

Population densities of male and female Musca vetustissima Walker were estimated from recapture rates of marked flies in baited fly traps. Marked flies of laboratory and field origin were equally trappable. Trap catches of field flies were also compared with net catches for which the human collector was the source of attraction, and relationships are presented for estimating population densities based on both sampling methods. Estimates of fly density from trap and net catches at fixed locations have similar precision, coefficients of variation being approximately 55% for both males and females of M. vetustissima. Comparison of estimated fly densities (flies/ha) and annoyance indices, estimated numbers of flies approaching a collector each minute at 29.5°C, in ‘good’ and ‘bad’ fly years suggests that M. vetustissima is a potential nuisance whenever population densities exceed 1000 flies/ha.

The behaviour and pest status of the rice stem borers Diopsis longicornis Macquart and D. apicalis Dalman were investigated in the Republic of Guinée, particularly during the dry season. The variables were direct seeded and transplanted rice, and three (1988, 1989) and four (1987) planting dates. Transplanted rice was damaged nearly three times more than direct seeded rice in the dry season, but no significant difference was detected during the wet season. As previously observed in other West African countries, D.apicalis only occasionally damages rice in Guinée. Contrary to findings elsewhere, D. longicornis was not an important pest of Guinean rice, infesting only 5% and 3% of stems over the three dry and the two wet seasons, respectively. However, year round rice production could promote build up of the diopsid population if dry season planting is not sufficiently delayed (45 days) after the last rains of the wet season.

Entomological indicators such as vector density, distribution, biology and bionomics and their vectorial attributes are important parameters for measuring the pattern and intensity of malaria transmission. Although published articles provide evidence for the existence of associations between entomological indices and malaria transmission dynamics, none of them is able to establish a strong correlation. In order to address this issue, the present study aims to assess how malaria transmission is influenced and can be predicted by local major vector dynamics. We carried out an entomological assessment of major Anopheline vector abundance, habit/habitat, resting and feeding behavior, infectivity rates, and other entomological parameters. Results suggest that malaria transmission was correlated with a vector control intervention and non-intervention scenario in a high endemic region of Kalahandi district of Odisha, India. Amongst all indices, infective anthropophagic vectors established a strong positive correlation with malaria morbidity in comparison to infective or anthropophagic vector species during both the study periods. Though other entomological parameters influenced the transmission intensity, little quantifiable association was detected among study sites. This study provides strong baseline evidence of an association between entomological indices and malaria transmission dynamics, which could be used as an early warning system for outbreak prediction.

Lucerne labelled with 131I or 125I was used to mark field colonies of the harvester termite Hodotermes mossambicus (Hagen) in South Africa. The foraging area was delineated by plotting the distribution range of radioactive workers collected on the soil surface over a period of up to 57 days. Foraging areas of single colonies varied between 0.5 and 3.1 ha. These areas were not necessarily the exclusive territory of a single colony. Inter-worker aggression assays confirmed these conclusions.

The nut gall-mite (Eriophyes avellanae, Nal.) is one of the commonest species of gall-mites that occurs in this country, and it may be found infesting the buds of hazel (Corylus avellana) in almost any hedgerow and copse where this plant grows. The species is found also in America and in Continental Europe. Its life-cycle is very similar to that of the black currant gall-mite, E. ribis (Westw.) Nal.

We examined the life history consequences of cornicle secretion by Aphis fabae Scopoli in second and fourth instars, and its effects on host suitability for its parasitoid, Lysiphlebus fabarum (Marshall). Cornicle secretion did not affect aphid fecundity, but secretion in the second instar enhanced life table parameters, whereas secretion in the fourth instar affected them negatively, suggesting a higher cost of secretion in later instars. Secretion in either instar improved host suitability for L. fabarum. Although control and treated aphids were parasitized at similar rates, and with similar success, wasps developed faster and emerged as larger adults in aphids that had secreted, regardless of instar. Transgenerational effects were also evident. Progeny emergence was higher when parental wasps developed in fourth instars than in seconds, whether aphids secreted or not, and progeny were larger when parental hosts secreted in the second instar, but not in the fourth. Secreting fourth instars were preferred to controls by L. fabarum females in choice tests, but not secreting second instars, and fourth-instar secretion improved wasp emergence. When control aphids were attacked, second instars were more likely to secrete than fourth instars, whereas the latter were more likely to kick the parasitoid. Cornicle secretion reduced the probability of subsequent secretion events and the frequency of other aphid defensive behaviors, indicating energetic tradeoffs among defensive tactics. Overall, our results revealed that cornicle secretion by immature A. fabae exacts both physiological and behavioral costs and results in improved host suitability for its parasitoid.

The genus Pseudodoniella was proposed by China & Carvalho (1951) for the species pacifica from Keravat, New Britain. Recently two more species have come to hand, from Lae, New Guinea and Popondetta, Papua. They are new and are described and figured here. It has been found that in the genus Parabryocoropsis China & Carvalho (1951), two of the species then described, cheesmanae from Kokoda, Papua and duni from Keravat, New Britain, were incorrectly placed and should have been assigned to Pseudodoniella.

Three new trapping devices (Ml, M2 and M3 traps) were tested and compared with current trapping devices (the F3 and the Epsilon traps) for tsetse flies (Glossina spp.) in Zimbabwe. The most effective was the M3 trap which caught 80% and 73% more male and female G. morsitans Westwood and 110% and 39% more male and female G. pallidipes Austen, respectively. The mean catch for the standard Epsilon trap which was not so effective was six male G. morsitans, 24 female G. morsitans, 76 male G. pallidipes and 199 female G. pallidipes.

Characterization and gene cloning of acetylecholinesterase (AChE) in the insecticide-resistant (R) and -susceptible (S) insects have been reported in the past. However, the studies focused mostly on herbivorous pests, rather than predacious species, such as ladybird beetles. Using R and S Propylaea japonica (thunberg), a full-length cDNA sequence (2928 bp) of the ace1-type AChE gene was determined for the first time. The ace1 encoding a protein of 645 amino acids contained typical conserved motifs, such as FGESAG domains, catalytic triad, acyl pocket, oxyanino hole, choline binding site, peripheral anionic site, omega loop and conserved aromatic residues. R P. japonica displayed 50-times greater resistance to chlorpyrifos or mathamidophos with a significantly lower AChE sensitivity to paraoxon, malaoxon, chlorpyrifos or methamidophos than its S counterpart. Five amino acids in the ace1 of R P. japonica differed from those found in S P. japonica. One of them, F358S, located in the acyl-binding pocket, might play a crucial role in the resistance of the insect to organophosphates (OPs). Whereas, K493E and I538V, which were close to some of the conserved aromatic amino acids (i.e., H509, Y511, and W499) in the gorge, and G571R and T576A near C593 that formed the disulfide bonds with C471, might also involve in the change of insecticide resistance in P. japonica. AChE insensitivity and amino acid replacements, particularly F358S, might be the determining factors in the alteration of OPs-resistance in P. japonica.

An outbreak of body lice might require several control measures according to circumstances. Two types of fumigant action have been investigated in the laboratory and the field :—

(1) House fumigation for disinfesting typhus-contaminated premises.

Lice were fairly similar to bed-bugs in their resistance to the fumigants tested. In practice, 16 oz./l,000 cubic feet of hydrogen cyanide will kill lice and eggs : 2 lb. of sulphur/1,000 cubic feet is also successful if the wind is not strong.

(2) Bin fumigation of garments by saturated vapours.

The saturated vapours of solids such as naphthalene and paradichlorbenzene are extremely slow in action ; even with 20 hours exposure at 20°C. they are unreliable. Liquids such as heavy naphtha or trichlorethylene are much more promising.

For reading and criticising this paper I am grateful to Professor Buxton in whose department the work was done. My thanks are also due to the Medical Research Council for a grant.

Early last year five females of a species of Eupelmid were received from Mr. B. A. O'Connor of the Department of Agriculture in Fiji, where they had been bred in the previous November from eggs of the Phasmid, Graeffea crouanii (Le Guillou). Although this Phasmid, which is a pest of the coconut crowns, bad been bred many times before, no such parasite had occurred previously. As this species was unknown to the author, more material was requested.

In plot trials with seed dressings on late-sown oats against shoot attack by frit fly, Oscinella frit (L.), chiefly near Cambridge, England, γ BHC, parathion, dieldrin, heptachlor, Rogor and WL 1650 (Telodrin) (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-niethanophthalan) (dry and wet) reduced the attack but the effect was variable and for the most part not appreciable.

In 1952 and from 1956 to 1960, trials were made on the effect of late sprays of various insecticides applied to late-sown oats when symptoms of frit-fly attack were already conspicuous and sometimes severe. An advantage of this type of treatment over preventive sprays is that it ensures that the treatment is applied only where and when necessary. Single sprays of parathion, dieldrin, γ BHC and Rogor prevented or markedly reduced further attack and they were most effective when applied within about 15 days of the beginning of egg-laying and when plants were in the young seedling stage. Compared with the best treatment of two early preventive sprays of DDT there was only a slight reduction in yield. Parathion and to lesser extent γ BHC killed many larvae inside the shoots and probably prevented others from entering the shoots.

Over the last 40 years, many types of population genetic markers have been used to assess the population structure of the pest moth species Helicoverpa armigera. While this species is highly vagile, there is evidence of inter-continental population structure. Here, we examine Z-chromosome molecular markers within and between Chinese and Australian populations. Using 1352 polymorphic sites from 40 Z-linked loci, we compared two Chinese populations of moths separated by 700 km and found virtually no population structure (n = 41 and n = 54, with <1% of variation discriminating between populations). The levels of nucleotide diversity within these populations were consistent with previous estimates from introns in Z-linked genes of Australian samples (π = 0.028 vs. 0.03). Furthermore, all loci surveyed in these Chinese populations showed a skew toward rare variants, with ten loci having a significant Tajima's D statistic, suggesting that this species could have undergone a population expansion. Eight of the 40 loci had been examined in a previous study of Australian moths, of which six revealed very little inter-continental population structure. However, the two markers associated with the Cyp303a1 locus that has previously been proposed to be a target of a selective sweep, exhibited allele structuring between countries. Using a separate dataset of 19 Australian and four Chinese moths, we scanned the molecular variation distributed across the entire Z-chromosome and found distinct blocks of differentiation that include the region containing Cyp303a1. We recommend some of these loci join those associated with insecticide resistance to form a set of genes best suited to analyzing population structure in this global pest.