The bagworm, Eumeta variegata (=E. japonica), is a well known pest on orchard and street trees, and is extensively distributed in central and southern parts of Japan. E. variegate has been reported to be on the verge of extinction in recent years in Japan because of parasitization by the newly invaded tachinid fly, Nealsomyia rufella. In this study, the abundance of E. variegata and their present parasitism by N. rufella in Kochi Prefecture, located in the southwestern part of Japan, were investigated. The silken bags of E. variegata larvae were collected from December 1999 to May 2000 and from September 2000 to April 2001 throughout the plains in Kochi Prefecture. After the length of each silken bag was measured, it was opened to determine whether or not it had been parasitized. The percentage of parasitism ranged from 0 to 96.4% in each collection site, having a tendency to be higher in the urban area in the central part of Kochi. All living bagworms were reared in the laboratory to determine the parasitization by N. rufella, and it was found that N. rufella parasitized not only mature larvae but the younger larvae of E. variegata. This finding suggests that N. rufella is able to maintain its life cycle using only E. variegate as hosts. Sometimes the puparia of N. rufella collected in the field were parasitized by parasitic wasps which consisted of seven species in four families. The effect of these wasps on the population of N. rufella is unknown.

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Chorthippus brunneus (Thunberg) (Orthoptera: Acrididae) and C. jacobsi (Harz) (Orthoptera: Acrididae) are reported as a host of Blaesoxipha grisea Meigen (Diptera, Sarcophagidae), on the basis of male and female flies reared from male and female adults of the above mentioned grasshoppers collected at Taranilla, Leon, Spain. This is the first host record for the fly species.

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Three species of astigmatid mites which infest mason bees, i.e., Chaetodactylus hirashimai, C. nipponicus and Tortonia sp., are known to occur in Japan. Two of them, C. nipponicus and T. sp. are sympatrically distributed in central and northern Japan. They are cleptoparasites of Osmia cornifrons, which is utilized as a pollinator of apples. The invasion/infestation patterns of these mites were studied through a survey conducted at 24 apple orchards in various localities during winter between 1999 and 2001. A population of O. cornifrons was reared in Sendai City, northern Japan, in spring of 1999 so as to analyse the synchronization between invasion/infestation of mites and nesting activity of host bees. As overwintering stages of C. nipponicus, phoretic and cyst-like deutonymphs were found together in the same cells, while 5 stages (larvae, protonymphs, tritonymphs, adults and phoretic deutonymph) were confirmed to hibernate in Tortonia sp. The cyst-like deutonymphs were absent in the latter species. In C. nipponicus, the percentage of phoretic deutonymphs was extremely high (up to 99.6% per host cell), while in T. sp. was lower (6.6% in total). The life type of these 2 mite species is regarded as phoretic- and dweller-like, respectively. The difference of their life types between 2 mite species are enable the partitive use of the pollen-mass stored in the same nests. The following features, regarding to the invasion/infestation patterns, were recognized. 1) Mostly, the first nests made in tubes were infested by both species of mites. The number of cells infested by C. nipponicus extended up to 9 cells, but usually the inner ones were apt to be infested. On the other hand, infested cells were found throughout nest tubes in T. sp.; 2) Distribution and numbers of dead cell contents in a nest by infestation of mites differed between 2 mite species. Only 1-3 cell contents were killed in C. nipponicus, and none killed in T. sp.; 3) Prior to feed on the stored pollen-mass, both species of mites killed hosts. However, they were able to kill hosts of which stages were from egg to early third instar larva. To kill host eggs, it was needed more than 50 adult mites. Those hosts that escaped from slaughter survived and formed normal cocoons; 4) Coinhabiting with C. nipponicus and T. sp. in the same host cell was less frequently occurred (7.1% in total). In these cells, the individual ratio of C. nipponicus was always higher than that of T. sp. The 5 overwintering stages, except phoretic deutonymph, in Tortonia sp. were not all in diapause. These stages began to develop into the next stages sooner, when new food was given under warm temperature. The phoretic deutonymphs of both mite species activated their development by clinging to host bee bodies in both mite species. The cyst-like deutonymphs of C. nipponicus developed into the tritonymphs when subjected them to the scent of host bees.

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Platurocypta punctum (Stannius) (Diptera: Mycetophilidae) was firstly recorded from Japan based on the adult specimens emerged from a fruiting body of Fuligo septica (L.) (Myxomycetes: Physarales: Physaraceae). We observed the larvae feeding on spores within the fruiting body at Kamigamo Experimental Forest in Kyoto, central Japan. P. punctum may be closely associated with slime molds.

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Spermatogonial and spermatocyte chromosomes of three dytiscid species (Dytiscus marginalis czerskii, D. dauricus and Cybister japonicus) were examined with the air-drying and Crozier's techniques. The former two Dytiscus species possessed 2n=37, n=19 (M I), n=19 and 18 (M II) and the third one did 2n=43, n=22 (M I), n=22 and 21 (M II). Thus, the sex chromosome constitution in males of these three dytiscid species is suggested to be XO. The X chromosome of spermatocytes of D. marginalis czerskii has been entirely heteropycnotic in the leptotene stage of M I prophase. The spermatogonial chromosomes of the two Dytiscus species showed cytogenetically unique staining profiles in the pericentromeric regions of four pairs (Nos. 1-4) of D. marginalis chromosomes and in six pairs (Nos. 1-6) of D. dauricus chromosomes, all of which prematurely condensed with marked intra- and inter-individual variations, being less stained with Giemsa, but darkly stained after C-banding. Such unusual staining regions, regarded as C-blocks and termed "less staining region (LSR)", were not detected in any of the Cybister japonicus chromosomes at all. Numerical variations of chromosomes in Dytiscus reported so far may have been caused by the presence of LSR. The two species of Dytiscus shared a karyological feature with a similar pattern of distribution of LSR and closely related chromosome constitution. A plausible factor forming LSR is briefly discussed.

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Pediobius fraternus (Motschulsky) (Hymenoptera: Eulophidae) has hitherto been recorded from Oriental and Australian Regions and the eggs of Tenodera aridifolia (Stoll) (Mantodea: Mantidae) are known as host. We have reared many specimens of P. fraternus from an egg case of Hierodula patellifera (Serville) (Mantodea: Mantidae) collected on Iriomote Island, southwestern Japan. This is the first record of E. fraternus in Japan.

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Females of the giant water bug, Lethocerus deyrolli (Vuillefroy) lay egg masses on vegetation or branches above the water surface. The male cares for the egg mass and supplies it with water until hatching, which is synchronized between individual eggs in an egg mass. Hatching was classified into two steps. In the first step (which occurs only in eggs supplied with water by the male), the upper part of the chorion surrounding the micropyle is lifted up and the nymph appears covered in a transparent glossy membrane (called chorion hatching). In the second step, the transparent membrane tears inside (called embryonic molting). Once embryonic molting starts in one egg, it quickly spreads through neighboring eggs, suggesting some kind of communication. The emerged nymphs spread and move their front legs (called front leg movement) and the movement spreads to all nymphs in the same egg mass in a chain reaction. Finally, they drop into the water simultaneously. In egg masses divided artificially into two groups by removing eggs, chorion hatching occurred over about 20 to 40 minutes, whereas both embryonic molting and dropping into the water occurred within a few minutes. In egg masses divided in half using a substrate stick, all hatching processes occurred separately between the two divided groups, but was synchronized within the groups. The hatching time of divided eggs seemed to be depended on the amount of water supplied by the attending male. The male seems to control the timing of chorion hatching, while embryonic molting and dropping into the water appear to be triggered by communication between developing nymphs.

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