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The influence of two photoperiods (12 and 20 hours of light per day) and different constant (25, 20, 15.5, 12.5 and 4°) and fluctuating temperatures on the hatching of the larvae of Ae. caspius caspius from Bairam-Ali (Turkmenia) has been studied experimentally. The induction of winter egg diapause has been established to be under photoperiodic and temperature control. In eggs laid by short-day treated females the tendency to enter diapause is more expressed (55.9%) as compared with those laid by long-day exposed females (1.6%); in this case the eggs were kept at 12.5° and in shortday regime. The low temperature 4° increases only slightly the number of diapausing eggs (13.9%). The temperature which fluctuate twice during twenty-four hours being combined with short-day regime is more effective (the action of low temperature coincides with the scotophase). Even in the progeny of long-day exposed females the termorhythms 13—21, 8—20 and 4—20° induce to enter diapause correspondigly 27.4, 22.8 and 59.9 per cent of the eggs.

On the basis of morfological analysis of ecological, paleontological and zoogeographical data the main evolutionary trends of biting midges are established, the description of the hypothetical ancestor of the family is given and the apomorphy and plesiomorphy of the genera are analysed. As a result, the subfamily Palpomyiinae is separated from Ceratopogoninae, the tribes Culicoidini and Ceratopogonini are united and the genus Dasyhelea is transferred to Forcipomyiinae.

Information is given on the fleas of Citellus fulvus from Kazakhstan and Central Asia (geographic distribution; occurrence on the subspecies of the host; abundance index and per cent ratio between the species of fleas in homogenous colonies of the host, in those mixed with population ons of the great gerbil and in various parts of its distribution area; the infection rate with the plague agent). A map of the distribution of the large-toothed suslik and the great gerbil and the sites of the isolation of plague microbe cultures from fleas is presented.

Ability of hungary females of Ixodes persulcatus, Haemaphysalis concinna and Dermacentor silvarum to feed and lay eggs after having been exposed to different DDT doses (LD1₀₀) has been studied. The ticks heavily injured but still mobile can feed on the host and lay eggs, i. e. to overcome the poisoning. Clutches laid by these females do not differ from control ones. Loss of mobility deprives the ticks of the ability to fed. An increase in DDT dose (LD₁₀₀ X 100, experiment with I. persulcatus) does not allow the ticks to feed even if the ability to movement is preserved.

Integument fine structure of Hyalomma asiaticum nymphs during their feeding and starvation has been studied. In hungry nymphs hypoderma has an ultrastructure typical for hypodermal cells of arthropods in the intermoulting period and is characterized by a poor development of granular endoplasmic reticulim, small number of mitochondria and absence of Golgi complexes. The apical surface of the cells is covered with short irregularly scattered microvilli. The cuticle consists of the procuticle, which has a homogenous fine-granular structure, and four-layered epicuticle. During the feeding period hypodermal cells greatly increase in volume and the elements of granular endoplasmic reticulum and metachondria increase in number. Golgi complexes and a variety of apical vesicles have been observed. The number of microvilli on the apical surface increases that is accompanied by a cuticle growth. Procuticle, which is being formed within this period, has a lamellar structure.

A new technique is suggested for absolute registration of adult ixodid ticks with an improved furrow plough. Due to this the number of ticks can be estimated per square unit о various biotopes. As a result of registrations conducted in 1973 the density of ticks populations from the main landscape zones of eastern Sikhote-Alin (from watershed spruce-abietic forests to coastal oak woods) was estimated for the first time.

Caligus kurochkini sp. nov. is described from the gills of Usacaranx georgianus captured in April of 1966 and 1967 in the Great Australian Bight. The new species is most close in some characters to C. confusus Pillai, 1961 and C. constrictus Heller, 1865.

Fresh water mollusks Galba palustris and Bithynia tentaculata feed on ascaris eggs, destroy them (10 to 20%) and hinder their development as compared to control ones. Thus, this mollusks participate in the purification of water bodies from ascaris eggs. Eggs swallowed by mollusks of the genus Radix develop normally. Consequently Radix serve for scattering eggs over the bottom of the water body.

Many trematodes parasitic in the oral cavity, pharynx or oesophagus of snakes and birds or in the cloaca of birds possess a sac-shaped dilation of the uterine distal portion or the organ itself is sac-shaped. Trematodes possessing such uterus lay periodically more or less large portions of eggs. The time of egg laying depends on the frequency of some functions of the host's organs (food capture by the host, swallowing the food, defecation), which the trematodes inhabit.

In the scolex ganglia of the cestode Pelichnibothrium speciosum uni- and multipolar neurons can be found. Their neuroplasm is rich in free ribosomes. The ergastoplasmas membranes are frequently arranged in compact finger print-like structures. The nerve cells processes form tight junctions which cannot be interpreted as synaptic contacts.

Genetic peculiarities of mice were studied in regards to their susceptibility to toxoplasms. Differences in susceptibility to little virulent toxoplasms in mice of 9 different lines are shown, which manifest at all stages of the infection process or only at acute or chronic stages. The susceptibility of 6 lines of mice to virulent toxoplasms was found to be equally high.

Measurements were conducted of five species of Lamblia mounted and stained with ferreous hematoxylin. In order to obtain comparable results only mature trophozoites with medial bodies were measured. It was shown that the totality of biometrical indices of mature trophozoites is specific for each species studied; this demonstrates their distinct status and is contrary to Filice's view (1952). Of the studied species trophozoites of man (L. intestinalis), rabbit (L. duodenalis), vole (L. microti) and rat (L. simoni) have the same shape of the body but differ in absolute sizes. Trophozoites of the parasite of mice and rats, L. muris, differ from other species in a shorter body and in having spherical medial bodies. In this connection a question is raised concerning the according of a higher taxonomic status to this species.

Two new species of trematodes, Gonocerca macrouri sp. n. (fam. Halipegidae) and Hemiurus macrouri sp. n. (fam. Hemiuridae) from the stomach of Macrourus rupestris L. are described.

Two new species of parasitic Protozoa are described, one of Myxosporidia and the other of Peritricha Sessilia. Myxobilatus schulmani sp. n. from Pungitius pungitius is near to M. paragasterostei but differs from it by the rhombus form of the spore, by less dimension of polar capsules. The spore of M. shulmani is longer and less broader than that of M. paragasterostei. Apiosoma longiciliaris sp. n. was found on the gills of Esox lucius and Phoxinus phoxinus. It is near to A. dallii but its micronucleus is situated over the macronucleus and has a stick like form.

Dismountable magnifying optic device was designed and tested in order to rise the labour productivity, sagety and quality of investigations in water bodies, hatching sites of black flies larvae, mosquitoes and other small hydrobionts.

Systematic control of mosquitoes (Culex pipiens molestus) has begun in Leningrad since 1968 when undertaken inspections revealed mosquitoes and their aquatic stages in 21.8% of basements. All hatching sites of mosquitoes were registered and sanitary, hydrotechnical and destroying measures were carried out there. During the period of 1968 to 1973 the basements were cleaned, in 509 of them hydroisolation was made and many were dried. Anually chemical treatment of basements was undertaken and for 6 years the treated area amounted to 6.000000 m². As a result, the percentage of flooded basements decreased from 25.8 to 7.1% and the hatching sites of mosquitoes — from 21.8 to 9.1%. The total population of mosquitoes decreased 43 fold.

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Summary is absent.

Summary is absent.