A 100-mg sample of cockroach gel bait (Maxforce gel K) was placed on a plastic sheet and kept at 25 to 27℃. The bait lost about 50% of its weight within a week through drying, but subsequently the weight did not change very much. The bait dried for 4 weeks was 2/3 as attractive as fresh bait, and that dried for 9 or 16 weeks was 3/4 as attractive. No or very few cockroaches chose bait dried for 32 weeks and/or one year. However, all cockroaches took the bait and died when presented with the bait dried for one year alone without food. Gel bait (150 mg) dried at 50℃ lost about 57% of its weight by drying for 3 or 9 days, and about 59% by drying for 27 days, suggesting that the higher temperature resulted in enhanced drying. Furthermore, the dried bait did not loose attractiveness to the cockroaches or its lethality during the drying period. High-temperature drying may actually help maintain the bait quality. Fresh bait sprinkled lightly with flour was as attractive to the cockroaches as the fresh bait. However, bait buried 5mm in flour was no more attractive to the cockroaches than the flour itself, which was not very attractive to them.

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Seventy-two houses infested by dark-brown ants, Lasius japonicus Santschi, were surveyed from April 2005 to September 2006 in Sapporo and neighboring cities. The ants were active in the warmer seasons, especially in June. The infested houses were categorized into two types: less than 5 years (30.6%) or more than 21 years (27.8%) after construction. These phenomena might be caused by changes in the external insulation in recent houses and the house deterioration in aged mortared houses.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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