In this paper, the reiterative mating ability of males of Spodoptera litura F. was investigated under semi-field conditions. Many males mated 4-7 times during their life in the laboratory condition, so that it was considered that they were able to mate several times even under field conditions. Such a reiterative mating ability in the male parallels its length of longevity. The male most actively mated at the 3rd night from emergence. When a single male was successively paired with a fresh virgin female for several nights, the fertilization rate of eggs in the female was not greatly changed by the difference in the order of matings in that male. The females which mated successfully laid their eggs in the largest numbers on the 2nd night following the night of mating, but the female which failed to mate (virgin female) did so on the 5th night.

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The amino acid and sugar composition of sugar beet leaf tissue injured by Lygus disponsi were quantitatively and semiquantitatively analyzed. Thirteen amino acids and five undentified ninhydrin positive compounds were detected in the tissue. Concentrations of all thirteen amino acids increased remarkably in injured tissue, while the composition pattern of individual amino acids was found to be markedly different from that of uninjured tissue. Five kinds of sugars (including an unidentified sugar) were detected in injured tissue and all of these with the exception of glucose were more abundant in injured rather than uninjured tissue. The unidentified sugar was not detected in uninjured tissue. The relationship between the alteration of the pattern on these compounds in the tissue and the injury (leaf malformations) is discussed.

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Basic studies on the minute pine bark beetle, Cryphalus fulvus NIIJIMA, a species attacking the Japanese red-pine, Pinus derstflora SIEB. et ZUCC., were conducted under both laboratory and field conditions, using the bait traps.Traps with the virgin fermale-infested logs are strongly attractive to newly emerged beetles of both sexes. After emergence, the females disperse flight and attack hosts as pioneers. Mass attack flight then occurs in response to the species-specific pheromone produced by the invasion of pioneers. The maximum response to the trap is achieved between the third and fifth day after the introduction of females into the log. The response flight is influenced by temperature and wind. With an increase in wind speeds, the dispersal flight is directed toward the inside of forest stands. Diurnal patterns in response to the trap and of emergence of the beetles are similar in general form, having a single peak in the late afternoon when the environmental factors are favorable.The female produces a population aggregation pheromone that both attracts and arrests the adult beetles.

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The larvae of the red-headed type (OLIVER's orange race) of Hyphantria cunea in Arkansas, U. S. A., make a silken-web which is remarkably different in shape from that of the black-headed type. The former type is considered to be reproductively isolated from the black-headed type by its seasonal life cycle and host preference. Laboratory experiments revealed that (1) the duration of larval and pupal development of the red-headed type reared under constant temperature on artificial diet was longer than that of the black-headed one; (2) the critical photoperiod for the induction of diapause was between 14 and 10 hr; (3) feeding activity of the red-headed larvae was nocturnal while the black-headed larvae fed in the day-time as well as at night; (4) full grown larvae tended to hide behind something under artificial illumination ; and (5) the shape of the web-nest spun by red-headed larvae was greatly different from that of black-headed larvae. Some of the black-headed type collected from the Canadian Maritime Provinces entered diapause at 18 hr photoperiod, suggesting the possible occurrence of an obligatory diapause.The adults of red-headed and black-headed types could easily copulate with each other. Hybrids between red-headed males and black-headed females, having an intermediate larval color, grew at a developmental rate that was similar or somewhat higher than that of the black-headed type. Feeding and web-making behavior of the hybrids was of an intermediate nature between the two parental types. Inbreeding between F₁ moths and the back-cross with adults of the two types gave viable larvae.

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Coloration and external characters of the two types of Hyphantria cunea (DRURY) which differ in behavior and their hybrids are described. Considerable differences were found in color of the larvae between them but no other taxonomical difference could be found in the larval and pupal stages. There was a slight difference in the male genitalia between the two types, but individual specimens could not be identified due to the overlapping ranges of variation. The distribution of color patterns in F₂ larvae suggested that the larval color is not determined by a single pair of alleles.

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The penetration of dimethoate into the mite body was investigated as part of a broad study attempting to clarify the mechanism of dimethoate resistance in the citrus red mite, Panonycus citri McGREGOR. Although there was no apparent difference in dimethoate penetration between the resistant and susceptible strains by topical application with a micrometer syringe without distinction of the solvents for dimethoate, an interstrain difference in penetration was observed by a spraying method. Sixty-two and 64% of sprayed dose penetrated the cuticle into the mite body of the susceptible strains, Wakayama and Ogi, while only 44 and 15% of sprayed dose penetrated into the body of the resistant strains, Shuku and Shizuoka, by the 9 th hour following application. The difference in penetration rate of dimethoate is considered to be one of the factors involved in the mechanism of dimethoate resistance in the citrus red mites.

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Amino acids in honeydews of three species of planthoppers (Nilaparvata lugens, Laodelphax striatellus and Sogatella frucifera) and two species of leafhoppers (Inazuma dorsalis and Nephotettix cincticeps) were examined by thin layer chromatography and on an automatic amino acid analyser. The honedews excreted by N. lugens, L. striatellus, S. frucifera and I. dorsalis contained 18 kinds of amino acids, with a predominance in aspartic acid, asparagine, glutamic acid, glutamine and valine. On the contrary, the honeydew of N. cincticeps contained only a very small amount of most amino acids with the exception of aspartic and glutamic acid. Insects which suck rice seedlings in the germinating stage excreted comparatively fewer amino acids. Those sucking an artificial amino acids solution excreted the same kinds of amino acids as present in the ingested solution. When distilled water was sucked, only traces of amino acids were excreted. It seems likely that the free amino acids in honeydew excreted by the rice plant- and leafhoppers were mostly derived from the ingested plant sap. It is also considered that N. cincticeps preferentially sucks the xylem to the phloem when compared to the other species.

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