Eggs of 13 species of plant bugs were tested for parasitism by Gryon japonicum in the laboratory. Among those Leptocorisa chinensis, Cletus punctiger, and C. rusticus were hosts as suitable as Riptortus clavatus which was known as only one natural host of this parasitoid. Parastitism by G. japonicum of the eggs of L. chinensis and two Cletus species was also ascertained in the field.
The zoysiagrass billbug, Sphenophorus venatus vestitus CHITTENDEN (Coleoptera: Curculionidae), which is inferred to be introduced into Japan from the United States, has been found occurring in Fukuoka, Hyôgo and Tokyo Prefectures since the first discovery at a golf course in Okinawa Prefecture in 1979. Five adults (2 females and 3 males) of this species were captured by using pitfall traps at the bank of Yamato River in Osaka and Nara Prefectures in 1986, 1988 and 1989 (Table 1). This may be the first discovery of this species in both prefectures and the second record from the river bank after the record from the Tama River in Tokyo.
The eclosion hormone (EH) activities which can induce the precocious adult eclosion of the pharate-adults of Bombyx mori or Samia cynthia ricini were present in the adult heads of Pseudaletia separata, Bombyx mori, Samia cynthia ricini, Antheraea pernyi, Antheraea yamamai and Manduca sexta. These results indicated that EH is not a species-specific hormone among the lepidopteran insects.