Abstract
In order to clarify the life history, number of generations in a year and behavior of a Crambinae sp., every generations of the moth were collected by light traps in 1972 and each stages of them were reared under various conditions.
(1) Imago stage
Wing expanse and body length of adult male and female are about 19, 22mm and 8, 9mm respectively. They are covered with gray scales. Longevity of male and female is 3-5 days and 5-7 days respectively and oviposition period is 2-3 days. They start to fly at 7 : 20 p.m. and the most active time is from 8 : 00 to 8 : 30 p.m.. The activity decreases rapidly after that period. In case of the 3rd generation, flight activity occurs earlier than in case of the 2nd one. After the peak time of flight activity, the moth come down on turfgrass to copulate and oviposit. The number of generations of this species is 4 in a year. The 1st generation was collected from the middle of May to the last 10 days of June and the number was 503 ; the 2nd, from the last 10 days of June to the first 10 days of August and 841 ; the 3rd, from the first 10 days of August to the middle of September and 13426; the 4th, from the last 10 days of September to the first 10 days of November and 1872. The density of the moth increases rapidly in a short time because of their large number of eggs deposited and 4 generations in a year.
(2) Egg stage
The size of egg is 0.525×0.328mm in average. They hatch at a regular interval and hatchability is very high.
(3) Larval stage
Body length of the larvae is 0.8-1.0mm and they are covered with bristle and colored dark brown at the time they hatch. Mature larvae measure about 20mm. At room temperature, the larval period of the 1st, 2nd, 3rd and 4th genera-tion were 37, 26, 31 and about 230 days respectively. The degree of damages caused by larvae differs according to the kind of cultured turfgrass. That of Zoysia japonica Steud. is slightly less than those of Tifgreen, Tifway and Zoysia matrella Merr..
(4) Pupal stage
The pupal period at 30°C and 25°C was 7.2 and 9.2 days respectively.
(5) The damage by this species is most rampant from August to September and this is caused by the 3rd generation. Sometimes, turfgrass of green and fair way of golf-links is blasted yellow within 2-3 days. When many larvae overwinter, the damage may occur by the 2nd generation from July to August. By the time one can notice the damage, it would be impossible to suppress by splaying insecticides. Therefore, it is necessary to detect the occurance of the 1st and 2nd generation and initiate the control measures before their density become high.
