It cannot be said that any satisfactory division of the Tetrastichini has yet been proposed. With the exception of one or two easily recognised groups like Melittobia, Westw., Crataepus, Först., and Hyperteles. Först., the genera are ill-defined, and this is specially the case with Tetrastichus, Hal., and its immediate allies. It has become evident that the mesonotal furrows or impressed lines have not the value for diagnosis that many writers have assigned to them. Recently Kurdjumov (Revue Russe d'Entomologie, xiii, p. 246, 1913) has separated Tetrastichus from Geniocerus, Ratz., by the chaetotaxy of the submarginal, assigning to the former genus those species which have one, and to the latter, species with more than one bristle in this position. Such a division, I believe to be unnatural, as it is certainly inconvenient.* In the following descriptions I have included one species in Tetrastichus though it has more than one bristle on the submarginal. I think it impossible, in the present state of our knowledge of the Tetrastichines, to say what characters are of basal importance. For grouping species, the funicle (shape, segments and chaetotaxy), the position of the scrobes, the shape of the pronotum (especially whether straight-edged or emarginate posteriorly), the chaetotaxy of the mesonotum and the propodeon, give generally the most reliable clues, while specific characters appear to lie in colour, proportions and chaetotaxy of the wings. How far the ring joint can or should be used is doubtful. When consisting of a number of equal rings it may be of some assistance, but in other cases, the basal ring is much the greatest, and it is almost impossible to say whether the succeeding lamina is distinct or not. Even with an oil immersion difficulty may be felt, and there is the further question of the morphological equivalence of these laminae. In the present paper four species assigned to Tetrastichus are described; of these, three are grouped together, mainly on account of antennal and propodeal characters, the fourth I have placed with some others described from dipterous hosts, but if the absence of whorls of hair from the male funicle proves to be more fundamental than the antennal coloration and the propodeal sculpture, possibly all four should go together. In describing the antennae, details are given of the sensoria, which, though rather variable in number on any individual joint, are more constant for the funicle and club as a whole.

During 1926 and subsequently in 1927 the writer's attention was called to the presence of a mite infesting apples in newly planted orchards around East Mailing, Kent.

Three interconnecting cages, the largest of which was about 2 feet square, were used in experiments with Anopheles vagus bred from wild-caught larvae.

Variations in the arrangement of these cages showed that:

1. The mosquitos are quiescent by day, if not disturbed, whether kept in the light or in darkness.

2. If they are in complete darkness by night, as in a photographic darkroom, they fly vertically upwards. They will readily escape from a cage about one foot square, with a hold half an inch in diameter in the top, in their continued attempts to fly upwards.

3. They are attracted by a dim light at night and will fly sideways or to a lesser extent slightly downwards, in opposition to the tendency to vertical upward flight. In this way they can pass through openings which they would miss if in complete darkness. Light will not cause them to fly vertically downwards.

4. Anopheles maculatus is less responsive to light under these conditions, than A. vagus.

Using A. vagus, tests were made of the toxicity and residual effect of DDT, BHC and Chlordane as wettable powders on plywood panels. The order of toxicity when fresh was found to be BHC, Chlordane, DDT; the order of the residual effectiveness was DDT, BHC, Chlordane.

A considerable mortality occurred amongst mosquitos surviving the overnight tests with DDT and BHC, if they were kept for a further 48 housrs.

A larger proportion of females was killed than of males, especially by DDT and Chlordane.

BHC was shown to have a marked repellent effect, comparable with that of citronella, but whereas citronella repelled without killing, BHC repelled, but also caused a high subsequent mortality.

A. maculatus was tested once against DDT, and once against BHC in the main series of tests, and was much more readily killed than A. vagus, presumably because of its weaker response to light causing it to remain longer in the main cage in contact with the treated panels.

The date palm hopper, Ommatissus lybicus, is a key pest of the date palm, which is expected to be comprised of many allopatric populations. The current study was carried out to determine bacterial endosymbiont diversity in the different populations of this pest. Ten date palm hopper populations were collected from the main date palm growing regions in Iran and an additional four samples from Pakistan, Oman, Egypt and Tunisia for detection of primary and secondary endosymbionts using polymerase chain reaction (PCR) assay with their specific primers. The PCR products were directly sequenced and edited using SeqMan software. The consensus sequences were subjected to a BLAST similarity search. The results revealed the presence of ‘Candidatus Sulcia muelleri’ (primary endosymbiont) and Wolbachia, Arsenophonus and Enterobacter (secondary endosymbionts) in all populations. This assay failed to detect ‘Candidatus Nasuia deltocephalinicola’ and Serratia in these populations. ‘Ca. S. muelleri’ exhibited a 100% infection frequency in populations and Wolbachia, Arsenophonus and Enterobacter demonstrated 100, 93.04 and 97.39% infection frequencies, respectively. The infection rate of Arsenophonus and Enterobacter ranged from 75 to 100% and 62.5 to 100%, respectively, in different populations of the insect. The results demonstrated multiple infections by ‘Ca. Sulcia muelleri’, Wolbachia, Arsenophonus and Enterobacter in the populations and may suggest significant roles for these endosymbionts on date palm hopper population fitness. This study provides an insight to endosymbiont variation in the date palm hopper populations; however, further investigation is needed to examine how these endosymbionts may affect host fitness.

The genus Padaukia is newly described in the family Psyllidae. Its systematic relationships are discussed; seven species are included, five of which are newly described: P. cuanzae sp. n., P. javana sp. n., P. kino sp. n., P. macrocarpae sp. n. and P. usambarensis sp. n. An identification key is provided. Three species are known to attack economically important species of timber trees of the legumious genus Pterocarpus in tropical Asia.

(1) The Kabaw and Kale Valleys, separated by a low watershed and both draining through lateral gorges, have a combined length of some 250 miles and a width of between 4–10 miles. They lie at an altitude of approximately 500 feet above sea level.

(2) There is heavy rainfall during the months of June to September inclusive and little or no rain in the months November to April inclusive. The Kabaw Valley, the more northerly of the two, is forested and there are only small isolated clearings, but a big area in the centre of the Kale Valley has been cleared. Rice is the main crop grown.

(3) There appears to be no pre-war information about mosquitos and malaria. Information during the war was gathered by several different types of Unit engaged on different types of work but there is sufficient to give a fairly complete picture.

(4) The valleys are highly malarious throughout their length and breadth; only one village out of twenty-three examined had a spleen rate under 60 per cent.

(5) Transmission of malaria takes place throughout the year and is intense during the months May to December inclusive.

(6) 17 species of Anopheles are recorded. Common species during the rains are A. minimus, A. leucosphyrus, A. philippinensis, A. jeyporiensis, A. annularis, A. hyrcanus and A. vagus. A. minimus is only locally abundant at this time; A. leucosphyrus is widespread but confined to the forest.

(7) When the rain ceases, species such as leucosphyrus and vagus, which breed in pools and similar habitats, become reduced in numbers. Species such as philippinensis, jeyporiensis, annularis, hyrcanus and barbirostris, which breed in larger bodies of stagnant water such as rice fields, also become reduced in numbers during the dry season, though more slowly, because their breeding places disappear less rapidly. As the streams and rivers settle down, after the rains have stopped, conditions for A. minimus and A. maculatus become good and these are the only two common and widely distributed species in the dry season.

(8) During the dry season, sporozoite rates of A. minimus were 1/159=0·63 per cent, in October, 19/519=3·66 per cent, in December and 10/514=1·94 per cent. in May and it is an important vector and the only vector. A. maculatus does not apparently attack man and plays no part in malaria transmission. In September the sporozoite rate of A. minimus was only 1/332=0·31 per cent, and the important vector of the period of the rains appeared to be A. leucosphyrus with a sporozoite rate of 2/134=1·49 per cent.

(9) The status of A. leucosphyrus as a vector in the Indo-Burmese border region is discussed. There is good evidence that, under wartime conditions with troops operating in the forest, it is an important vector during the rains. Its significance in peacetime is less easy to assess; as only a few people live in the forest or at the forest's edge, its importance is probably not great. On the other hand it does not rest indoors, and, as in the past reliance has been placed on day catches, it may have been overlooked. There is, however, evidence that military operations in the forest produce conditions which lead to an increase in the numbers of this species.

(10) Adult collections were nearly all made at night in camps or villages. The species found in large numbers near man were A. minimus, A. leucosphyrus, A. philippinensis, A. jeyporiensis, A. annularis, and A. hyrcanus. A. minimus and A. leucosphyrus, the two definitely incriminated vectors, were the most successful at obtaining blood when the host, man, was protected by a mosquito net. The other four species, however, were sometimes filled with blood, undoubtedly of human origin and all may play some part in malaria transmission under war conditions. The chances of a specimen becoming infected were reduced under the conditions existing when the dissections were made and so moderately long series of negative dissections (Table XI) cannot be taken as conclusive evidence that any one species played no part in malaria transmission. In peacetime these four species may feed mainly on cattle, though a description is given of a night catch in a village where A. philippinensis was caught attacking man although cattle were available.

(11) In September very few of any of the eight common species were resting by day in the place where they fed at night and it is presumed that they spent the day in the forest. Unfortunately very few inhabited houses were visited and almost the only available catching places were Army tents and shelters. The results suggest, however, that all the species tend to rest in the forest rather than indoors. In December in the Kale Valley A. minimus rested in houses by day; in May in the Kabaw Valley it did not. It is believed that where, as in the Kabaw Valley, forest comes up to the edge of the village, A. minimus seeks shelter for the day in the forest, but that where, as in the Kale Valley, the village stands in a clearing, it rests by day in the houses near where it has fed. The facts observed, however, do not preclude the possibility of a seasonal change in resting habit. It is clear that A. minimus is not invariably a house rester and the importance of catching by night to gain a true picture of the mosquito population is stressed.

(12) A. hyrcanus was usually the first species to appear after dark, followed by A. philippinensis, A. leucosphyrus and A. minimus in that order, the last named being usually most abundant in the second half of the night. Time of greatest activity was, however, variable in all species. There were only a few isolated instances of Anophelines biting in the forest by day.

(13) A. hyrcanus was attracted to light.

(14) Larvae identified as A. pallidus with the aid of the standard Indian keys invariably proved to be A. philippinensis on emergence.

(15) The variation found in A. minimus was considerable and is briefly discussed. The only constant difference between A. minimus and A. aconitus was found to be the flavescence on the proboscis.

The opinion that trypanosomiasis of the T. pecorum type is, under favourable conditions, transmissible amongst domestic stock through the agency of blood-sucking flies other than Glossina has been expressed by several observers.

In three previous papers (Bull. Ent. Res. vii, pp. 1–18; viii, pp. 73–91; and viii, pp. 135–154) we have described early stages of a number of West African mosquitos collected at Accra and at other places in the Gold Coast. The present paper deals with a few more early stages of mosquitos, for the most part collected by one of us (A.I.) in the Northern Territories of the Gold Coast, and thus fills in a gap or two in the knowledge of the life-histories of these insects.

Dimorphopterus cornutus novaeguineae subsp.n. is described from Papua New Guinea. Adults and immatures were collected from dying rice and a lawn of carpet grass (Axonopus compressus). Members of the genus Dimorphopterus and allied genera are known as chinch bugs and damage Gramineae in the tropics and subtropics. The differences between this subspecies and D. cornutus cornutus Slater are illustrated and described in detail.

The presence of trypanosomiasis in cattle in the Province of Mozambique has made the question of tsetse-flies one of considerable interest and importance. During the past two-and-a-half years the writer has lost no opportunity of gathering information as to the whereabouts of tsetse-belts. It has been very difficult, because of the inaccessibility of most parts of the Province. The northern districts of Nyasa and Mozambique, for example, are practically impenetrable except for a few miles along the coast; no roads exist, and the natives, while not actively hostile, do not favour the intrusion of the white man. The northern part of the Zambesia district and the Tete district are likewise seldom visited by white men. It was not possible to organise a system of collecting reports of fly-belts from officials because of the small number of officials in these out-of-the-way regions. The writer has, however, been enabled to visit practically all accessible parts of the Province, and by questioning officials and natives and those who have been through the more inaccessible regions, has gathered considerable data. Specimens of fly have been secured from many of the places recorded. Although the few notes given are by no means complete, it seems best, however, to place them on record now.

The use of six cowpea varieties highly resistant to Aphis craccivora Koch in grafts (as resistant scion and rootstock) with the susceptible variety Prima indicated the presence of a graft-transmissible chemical involved in the resistance. Wrapping the resistant part in light-proof foil indicated that photosynthesis is involved in the production of the chemical. In a third test, intergrafting is involved in the production of the chemical. In a third test, intergrafting the resistant part with and without leaves confirmed the importance of photosynthesis in the transfer of resistance. Finally, covering the resistance intergrafts with foil showed that the accumulation of the chemical in the stem before the foil was applied was the major source of the graft-transmissible resistance.

These keys and illustrations have been prepared in response to many requests. They concern only those species of Anopheles which have been recorded as occurring in West Africa south of the Sahara Desert as far as the equator. Much of the material has been derived from the recent Monograph by the late Dr. A. M. Evans on the Anophelines of the Ethiopian Region published by the British Museum in 1938. Personal acquaintance with the Anophelines of East and South Africa and examination of the specimens in the collection of the Department of Entomology of the London School of Hygiene and Tropical Medicine have assisted in the preparation of the keys.

The writer was engaged on control measures against hopper bands of the Migratory Locust, Locusta migratorioides, R. & F., along the western (Nigerian) shore of Lake Chad from the middle of August to the end of October 1930.

Humidity measurements in air spaces in the soil of Glossina morsitans Westw. breeding sites during the hot-dry season in northern Bostwana proved that ground holes were significantly more humid than tree holes, fallen logs or leaves. Site humidity decreased between September and October but did not differ significantly between riverine and mopane woodlands. Pupal mortality data demonstrated an apparent advantage in the dry season shift of breeding to holes. The evidence is only circumstantial that humidity is involved in site selection.

The types of the new species described below have been deposited in the British Museum.

Some six years ago, it was correctly pointed out by Brèthes (Bull. Soc. Ent. de France, 1914, p. 59) that the generic designation Diatomineura, Round. (Archiv. Zool. Anat. Fisiol. iii, p. 84, 1864), is a synonym of Osca, Walk., (Ins. Saund., Diptera, Part i, p. 10, 1850—nec Walk., 1864, nec Sta;l, 1871). The first species mentioned by both Walker and Rondani is Pangonia depressa, Macq. (=Erephopsis lata (Tabanus latus), Guér.), and this species is designated by Brè as the genotype. Erephopsis lata, Guér., of Kertész’s Catalogus Dipterorum (iii, p. 165, 1908), must therefore be known henceforth as Osca lata, Guér., and the South African Tabanus barbatus, L. (Pangonia barbata, Auct.), and Pangonia fulvifascia, Walk., must be transferred to the genus Osca.

Probing behaviour (prior to parturition) and parturition of two clones (PS01 and N116) of the pea aphid, Acyrthosiphon pisum on two genotypes (near-isogenic lines (NILs)) (Q174_5.13 and Q174_9.10) of Medicago truncatula were investigated using electrical penetration graph (EPG) coupled with simultaneous visual monitoring for parturition. Line Q174_5.13 has been reported to show a phloem-based resistance to feeding in the clone PS01 but to be susceptible to the clone N116, whereas Q174_9.10 has shown to be susceptible to both aphid clones. The time taken to first parturition by clone PS01 was similar on Q174_5.13 and Q174_9.10. Prior to parturition, no aphids on Q174_5.13 contacted phloem, but 5% of the aphids on Q174_9.10 showed phloem salivation (recognized by EPG pattern E1). No phloem contact was observed with aphid clone N116 on either NILs of Medicago before first parturition occurred, and the time taken to first larviposition was similar on Q174_5.13 and Q174_9.10. The results indicate that the initiation of parturition of the clone PS01 and N116 on both NILs does not require the phloem contact and seems unchanged by a phloem-based resistance mechanism to feeding on Medicago. This finding suggests that host recognition and decisions about parturition occur before phloem contact or ingestion, and act independently on R-gene-mediated resistance.

We quantified the life table parameters and predation capacity of a generalist predatory mite, Typhlodromus bagdasarjani Wainstein and Arutunjan on five monotypic diets, including Tetranychus urticae Koch (TSSM) eggs in the presence (SW) and absence (SN) of webs, Trialeurodes vaporariorum Westwood (GHWF) eggs (G), honeydew (H), and maize pollen (M) as well as three mixed diets, including SN + M, SN + G, and G + M. Our results showed that the individuals fed on the mixed diets had a considerably shorter developmental time and pre-oviposition period (APOP), higher oviposition days, higher fecundity and population growth rate than those raised on the monotypic diets. Furthermore, we found that the mixed diet of TSSM and GHWF eggs was the most favorable diet, resulted in the highest fecundity and population growth rate, shortest developmental time and APOP. While TSSM eggs alone in the presence of webs and honeydew were the worst diets resulted in the longest developmental time, lower oviposition day, higher fecundity and population growth rate. Our data determined that TSSM has more nutritional benefits than GHWF for T. bagdasarjani. We observed the positive effects of pollen addition to prey on the predatory mite's immature and adult life-history characters; however, it reduced the predation rate. Overall, maize pollen could enhance ecosystem services provided against spider mites and whiteflies by positively impacting the increase of T. bagdasarjani population. This predator may be more effective when two prey species are available than when only one species is present.

Observations were made on crowded, laboratory-reared. 18–20-day-old males of Schistocerca gregaria (Forsk.) taking off in a wind tunnel. Depending upon the time of day, take-off, which was usually upwind, particularly at higher wind speeds, was related to food availability. Few locusts with full foreguts took off, especially at low air temperatures (20°C), while at high temperatures (35°C), 95% of ones starved for 6 h took off. At 30°C, there was little further increase with starvation for 24–30 h. Females containing large oocytes took off less readily than those with small ones. Take-off was also sometimes initiated by decreases in wind speed and light intensity, and sudden changes in air temperature. A distinct passing shadow stimulated take-off, but not the flickering shadows of other flying locusts. A period of flight immediately beforehand inhibited take-off. The results are discussed in relation to field observations.