Benzene hexachloride and DDT are relatively new insecticides and their veterinary value when administered orally to bovines has not yet been fully investigated.

The first series of experiments showed that 0·5 gm./kg. on two successive days of D. 929, was toxic; 0·25 gm./kg. on two successive days followed by 0·125gm./kg. on the 3rd and 4th days was well tolerated, and the benzene hexachloride remained in the blood in sufficient concentration to kill feeding tsetse and ticks up to the 41st day. After a single dose of 0·25 gm./kg. the benzene hexachloride remained in the blood for only 10 to 12 days, and failed to protect the animal from East Coast Fever when it was grazed on heavily infested pasture.

Five calves susceptible to East Coast Fever were dosed with D.929 and exposed to attack by the common tick species under African farming conditions. A dose of 0·125 gm./kg. given weekly protected a calf from East Coast Fever, but there was no protection when the same dose was given once a fortnight. A dose of 0·125 gm./kg. given weekly also protected, whereas 0·1 gm./kg. failed. At all these dosages the concentration of benzene hexachloride in the blood was sufficient to kill feeding G. palpalis during the period the calves were under treatment and for periods of 10 to 25 days after the final dose.

D.929 given to animals suffering from East Coast Fever and Trypanosomiasis had no effect on the course of these diseases.

Doses of 0·3 gm./kg. (39 mg./kg. gamma isomer) are toxic to young animals but older animals showed a greater tolerance. Hypersensitivity, muscular tremors, and general paralysis were the main toxic symptoms, and gross pathologicaal changes were most obvious in the liver and urinary system. The median lethal dose of benzene hexachloride given orally for calves is therefore lower than for small laboratory animals as recorded by Cameron (1945). Only crude benzene hexachloride powder (13 per cent, gamma) was used in the preserit experiments, but Slade (1945) has shown that this is markedly less toxic than the purified gamma powder.

Little experimental work was done with DDT as the results with benzene hexachloride were more promising both in the control of ticks and tsetse.

Apanteles carposinae, sp. n.

♀. Black; the front legs entirely (save for the black feet and for some occasional slight darkening on femora above and below, on tibiae above, and on coxae and tarsi), middle legs entirely (save for the black feet and for femora darkened above and below and for some occasional slight darkening on tibiae and coxae), hind coxae at apex below, hind trochanters and trochantines, hind femora (save above and below extensively), hind tibiae, hind tarsi (save for black feet and some darkening), and palpi, red testaceous; tibial spurs pale; wings infumated evenly throughout and the setae coloured; stigma, metacarp, and all veins, brown; stigma uniformly opaque.

♂. Black; front coxae (save at base), front trochanters and trochantines, front femora (save for darkening above and below, which is sometimes strong), front tibiae (save for strong darkening above), front tarsi (save for some darkening and the black feet), middle coxae (save at base or even basal half), middle trochanters and trochantines largely, middle femora (save for extensive strong darkening above and below), hind coxae at apex below to some extent in the lighter but not in the darker examples, hind femora (save for extensive strong darkening above and below), and palpi, red testaceous; the four posterior tibiae and tarsi, and the hind trochanters and trochantines, largely darkened throughout save perhaps in an occasional lighter example; tibial spurs pale; wings infumated evenly throughout and the setae coloured; stigma, metacarp, and all veins, brown; stigma uniformly opaque.

The types of the new forms described in this paper are deposited in the collections of the Zoological Survey of India, Kaiser Castle, Benares.

A soft scale found infesting mango in Israel is described from the female as Coccus elatensis sp. n. It is morphologically related to C. gymnospori (Green), which is redescribed.

Observations on the behaviour of Culex pipiens fatigans Wied. were made in 24 huts built and occupied by Africans on a sisal estate near Tanga, Tanganyika Territory. Catches were made in four huts each day, an exit trap being fixed on the window from 2 p.m. to 6 p.m. (evening trap) and replaced by another from 6 p.m. to 8 a.m. next day (morning trap), when a spray catch was made of the mosquitos still in the hut. Each hut was used only once a week, for 31 weeks, from December 1952 to July 1953. The females caught were sorted according to the stage of the gonotrophic cycle, as judged by external examination. The stages used were: I, no blood, no visible ovaries; II, stomach full of blood, ovaries small; V, little or no blood, ovaries fully developed; III and IV, intermediate between II and V.

An analysis of variance was performed on the results. Catches of both sexes showed a significant variation with time, which was not, however, correlated with rainfall. Significantly different numbers were taken in the traps and in the huts. Females were significantly most numerous in the hut catch, and males in the morning trap, the former result suggesting that most females spend more than one day in a hut. There were significant differences between the numbers of females in the different stages of the gonotrophic cycle, stages I and II together accounting for 80 per cent, of all females caught. The high proportion of stage I is attributed to delay between emergence and feeding, and of stage II to the taking of more than one meal during the gonotrophic cycle, later meals obscuring the state of ovarian development. There were significant differences between huts as regards the numbers of females caught, but not as regards males, and it is concluded that this is due to variations in the attractiveness of the inhabitants of the huts.

Females in stage I were most numerous in the morning trap, those in stages II–IV were taken only rarely in traps, but there was no significant difference between numbers of stage V caught in huts and in the two window traps. These results arse attributed to restlessness in both hungry and gravid females, and sluggishness in fed ones. All stages except III were significantly more numerous in some weeks than in others and this might be due to variations in either rate of reproduction, or rate of loss of mosquitos from huts. There were significant variations in behaviour in different weeks. For females, this is attributed to changes in the proportions of the stages with time and the dependence of behaviour on stage. For males, there is some evidence of a relation between behaviour and humidity outside the hut. For females, the distribution of stages between different places of capture changes with time, stages II and III being most consistently associated with hut catches, while the most variable behaviour is shown by stage V.

The necessity for behaviour studies on mosquitos in the field is pointed out, especially in relation to field trials of residual insecticides.

♀ Head: sides clothed with flat white scales, interrupted by a rather narrow horizontal band of flat black ones; two large patches of flat black scales on the top, separated by a rather narrow band of narrow white scales extending from the nape on to the front; a narrow line of narrow white scales bordering the upper part of the eyes. Eyes well separated. Proboscis and palpi black. First antennal joint blackish, greypruinose. Thorax: integument blackish, except for the reddish scutellum and a small pale spot on each side at the base of the postnotum. Prothoracic lobes and the space behind them clothed with flat white scales. Scutum clothed with narrow yellowish-white and blackish scales, the former arranged in definite narrow lines as follows: a median line extending from the front margin to a little in front of the scutellum, where it forks into two; a line on each side of this extending the whole length of the scutum, enlarged a little in front of the middle and sending a branch obliquely forwards from this point to the lateral angle of the thorax; and another line forming a border to the scutum. Scutellum with narrow scales, mostly yellowishwhite, but some black ones on each side of the middle lobe. Pleurae with several patches of flat white scales. Abdomen black, above with conspicuous pure white basal lateral patches and traces of yellowish-white basal bands on all the segments; venter black, all the segments with pure white basal bands. Eighth segment welldeveloped, only partly retractile; cerci short, rather broad and rounded at the tip.

When DDT and “Gammexane” were first used in Uganda for work on tick control, the absence of a rapid and simple chemical test made it necessary to evolve a biological method which would assess the killing power of the preparations in use. Such a method, if it is to be employed to assess the results of field work, should satisfy the following conditions;

(a) ticks should receive an initial wetting with the preparation comparable to that received when cattle are dipped or sprayed, and

(b) remain on a moist surface for a few hours, and then for a longer period in contact with the dried deposit, as in the case of the animal after it has been dipped or sprayed.

The surfaces of bags containing fumigated cocoa were sprayed with the macrodosage of 956 mg./sq. ft. DDT applied as a 5 per cent, suspension of wettable powder in water.

After exposure to an infestation of Ephestia cautella and Tribolium castaneum, no appreciable effect was obtained in preventing an attack by E. cautella, though the larvae appeared to choose unusual pupation sites on the surface of the bags. T. castaneum were rapidly affected and prevented from entering into the sacks.

Aphis spiraecola Patch is one of the most economically important tree fruit pests worldwide. The pyrethroid insecticide lambda-cyhalothrin is commonly used to control A. spiraecola. In this 2-year study, we quantified the resistance level of A. spiraecola to lambda-cyhalothrin in different regions of the Shaanxi province, China. The results showed that A. spiraecola had reached extremely high resistance levels with a 174-fold resistance ratio (RR) found in the Xunyi region. In addition, we compared the enzymatic activity and expression level of P450 genes among eight A. spiraecola populations. The P450 activity of A. spiraecola was significantly increased in five regions (Xunyi, Liquan, Fengxiang, Luochuan, and Xinping) compared to susceptible strain (SS). The expression levels of CYP6CY7, CYP6CY14, CYP6CY22, P4504C1-like, P4506a13, CYP4CZ1, CYP380C47, and CYP4CJ2 genes were significantly increased under lambda-cyhalothrin treatment and in the resistant field populations. A L1014F mutation in the sodium channel gene was found and the mutation rate was positively correlated with the LC50 of lambda-cyhalothrin. In conclusion, the levels of lambda-cyhalothrin resistance of A. spiraecola field populations were associated with P450s and L1014F mutations. Our combined findings provide evidence on the resistance mechanism of A. spiraecola to lambda-cyhalothrin and give a theoretical basis for rational and effective control of this pest species.

A method is described by which candidate repellents can be rapidly screened and evaluated by comparing them with a standard repellent or with each other. Mosquitos are confined in a petri dish, of which the top is covered with mosquito gauze and the bottom lined with two semicircular filter papers, one of which is treated with a standard repellent, the other with candidate repellent. The dish is placed in an apparatus through which passes a slow stream of air of standard temperature and humidity. Counts of mosquitos are taken every half minute on and above the two halves of the petri dish, which is jarred after every second count to change the position of the mosquitos. A total of 40 counts is taken, the dish being rotated through 180° after the 20th count. The index of reaction is determined as the mean excess of position records for the candidate repellent over those for the standard one.

The initial effectiveness and the persistence of various repellents have been compared. In tests against Aedes aegypti (L.), the repellency of N, N-diethyl-m-toluamide and of O-chloro-N, N-diethyl benzamide did not differ, but each significantly exceeded that of dimethyl phthalate (DMP). The loss of repellency of DMP with time was approximately linear.

Attention is drawn to various aspects and applications of the method, and to its advantages, particularly for rapid screening of repellents.

The use of chemical insecticides is the main control method for Blattella germanica worldwide. The prolonged and frequent use of insecticides produced the selection of insecticide-resistant individuals. The German cockroach is one of the most widespread urban pests in Argentina. In the last decades, resistance monitoring studies in this country demonstrated that there is a high prevalence of pyrethroid-resistant populations of B. germanica in the field. In this work, we studied the resistance mechanisms of a field-collected strain of B. germanica at toxicological, enzymatic, and molecular levels. A resistance ratio of 100 was obtained for the resistant strain when it was exposed to β-cypermethrin. The pretreatment with specific synergists (piperonyl butoxide and triphenyl phosphate) led to a significant increase in the toxicity of the pyrethroid, suggesting an involvement of oxidases and esterases in the detoxification of this insecticide. Moreover, esterase and oxidase activities in the resistant strain were 1.5-fold and 2-fold higher respectively, compared to the susceptible individuals. On the other hand, the voltage-gated sodium channel gene of the resistant cockroaches did not show nucleotidic substitutions in the domain II which are associated to knockdown resistance in this species. These results suggest that the main mechanism of resistance of the studied cockroaches' strain is metabolic, mainly due to an increase in the activity of oxidase and esterase enzymes. The results of this work in addition to other reports found in literature show that the extended use of a single active principle for cockroach control promotes the development of resistance leading to control failure in the field. In contrast, integrated pest management strategies include the use of different control tools in addition to chemical insecticides, which delay the appearance of resistance increasing the efficacy of pest control.

Beattie & Howland's recent studies of the bionomics of some tree-hole mosquitos emphasize the importance of the food factor, total organic nitrogen, and the apparent lack of correlation between hydrogen ion concentration and larval incidence. In Queensland mosquitos selecting such breeding-places are with a few exceptions distinctly arboreal, and the presence of domestic mosquitos in tree-cavities is dependent upon proximity to human habitations. It is a curious fact that when this is the case both Aëdes argenteus and Culex fatigans will breed in smaller accumulations of water than Aëdes notoscriptus does.

Appended herewith are the results of a recent survey made in midsummer of trees situated within the Brisbane Area of 385 square miles. Pine trees and gum trees do not lend themselves to the production of cavities and therefore offer very little opportunity for breeding.

The poincianas hold the highest actual percentage, but on account of the far greater number of figs containing potential breeding cavities, the latter constitute a greater actual menace. The amount of water contained in each cavity varies considerably with the time of year.

The pineapple plantations of Mauritius have sustained since 1937 severe attacks of mealybugs (Pseudococcus spp.) which threatened to ruin the whole crop in certain localities. These attacks result in a wilting of the plants, which may be due to a toxin secreted by the bugs during their process of feeding.

On the basis of specimens from New Guinea and New Britain, the genus Dynamenais Kirkaldy (Pyrrhocoridae) is re-defined, four species and one subspecies are described in the new subgenus Syncrotus (Syncrotellus) (Pyrrhocoridae), and two species are described for the new genus Goilalaka (Pentatomidae). S. (S.) similis sp.n. was recorded from cacao, and S. (S.) madanganus sp.n. and G. rubroruga sp.n. from Solanum spp.

In pot experiments, the ability of newly hatched larvae of the wheat bulb fly, Leptohylemyia coarctata (Fall.), to move through nine in. of soil and infest wheat plants was tested for three different types of soil: sandy loam, clay loam and peaty loam and also clay loams at different levels of acidity. Each soil was inoculated with 200 freshly hatched larvae and the effects associated with soil were measured by the number of larvae subsequently recovered from infested plants.

The larval recoveries for different soil types were: sandy loam 28 per cent., clay loam 19 per cent, and peaty loam 2 per cent. The larvae could infest plants grown in clay loam within a pH range of 4·9 to 7·8 and the results suggested a possible optimum at pH 6·2. The relative failure to infest in peaty loam appeared to be due to this soil impeding larval movement rather than interfering with the mechanism of host-plant location.

A revised key is given to the Enicospilus antefurcalis (Szépl.) species-group, some species of which are parasites of Lepidoptera of economic importance, of the Afrotropical region. One Oriental species, E. laqueatus (End.), is recorded for the first time from Africa and two species, E. watshami sp. n. and E. polemus sp. n., are described.

The following notes and descriptions are based on material received by the Entomological Research Committee, who have kindly presented the types of the new species to the National Collection.

Only a very strong dose of 0·5 mg of hempa caused necrosis in testes of Locusta migratoria (L.). The apical cells, spermatogonia and primary spermatocytes became pycnotic and the germ cells were disorganised. Multinucleated cells also developed, due to failure of spindle formation, and a few hypertrophied spermatids occurred. In ovaries the chromatin of the follicular epithelial cell nuclei was abnormally fragmented; nuclei of the follicular epithelial cells became pycnotic; germinal vesicle was badly damaged; cytoplasm of the follicular epithelial cells was drawn into the peripheral empty space formed by the contraction of the ooplasm; the follicular epithelium degenerated later; and yolk formation was inhibited. With increased doses and post-treatment periods necrosis became more marked. Hempa was more effective in the ovary than in the testes of L. migratoria.

Site and time effects are important factors determining trap catches of tsetse flies. These factors may interact significantly and therefore confound interpretation of time series data used for population monitoring. We therefore investigated the magnitude and importance of site × time interactions in trap catches of Glossina pallidipes Austen and G. longipennis Corti using a 2200 trap-days (400 trap-months) data set. The interaction was found to be siginificant (p<0.05) in 46–100% of the combinations of different numbers of months and sites between 2 and 12. The mean percent variance due to the interaction ranged between 4% and 28% for G. pallidipes and 12% and 36% for G.longipennis. The interaction was usually less important than the effect of site alone but more important than the effect of time alone. These results suggest that tsetse researchers should examine critically the adequacy of existing approaches to population monitoring with traps and to testing new traps and odour baits.

The genus Isozulia is re-characterized and compared with Aeneolamia. Two species are transferred from Aeneolamia to become I. astralis (Distant) comb. n. and I. christenseni (Lallemand) comb. n., and I. flamen Fennah is reduced to a subspecies, I. astralis flamen, stat. n. Two populations from Ecuador and Peru are described as new species, I. minor sp. n. and I. charaxus sp. n., respectively, and a population of I. christenseni in Jujuy Province, Argentina, is recognised as a distinct subspecies, I. c. jujuyana subsp. n. Both this subspecies and I. minor are reported as attacking sugarcane.