. Cooperative economic insect report. Beneficial insects; Insect pests. - 349 - INSECTS NOT KNOWN TO OCCUR IN THE UNITED STATES ARROWHEAD SCALE (Unaspls yanonensis (Kuwana)) Economic Importance: The species, also called yanone scale, is one of the most injurious scale Insects of citrus in Japan. Many trees have been killed by it in the Nagasaki area of Japan and large parts of infested groves have been seriously infested. Even at a distance, infested trees may be recognized because of the large masses of white male cocoons on the foliage. Females are usually seen on the twigs and small branche
. Cooperative economic insect report. Beneficial insects; Insect pests. - 349 - INSECTS NOT KNOWN TO OCCUR IN THE UNITED STATES ARROWHEAD SCALE (Unaspls yanonensis (Kuwana)) Economic Importance: The species, also called yanone scale, is one of the most injurious scale Insects of citrus in Japan. Many trees have been killed by it in the Nagasaki area of Japan and large parts of infested groves have been seriously infested. Even at a distance, infested trees may be recognized because of the large masses of white male cocoons on the foliage. Females are usually seen on the twigs and small branches as well as the fruit. Although the scale was de- scribed in Chionaspis in 1923, it was known in Prontaspis from that year until 1949. Distribution: China (citrus areas of the southeast mainland), France (Cote d'Azur), and Japan. Hosts: Many species of General Distribution of Unaspis yanonensis (Kuwana) Life History and Habits: Under conditions in Japan, females and sometimes ma'ie pupae have been known to hibernate. Females are ovoviviparous and each may re- duce about 140 nymphs in the first generation, 170 in the second and 40 in the third. The nymphs of the first generation appear about mid-May in the north and a second nymphal peak takes place about 10-15 days later. ' In southern Japan, nymphs of the first generation occur approximately one month earlier. At temper- atures of 68° F., development of first stage nymphs requires nearly 25 days and the second stage about 18 days. First generation nymphs may be found up to August, whereas those of the second and third are present almost to November. Three generations a year occur in Japan. Hemiptera: Diaspididae No. 176 of Series. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Animal and Plant Health Service. Plant Protection and
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