13 



THE JAPANESE ROSE BEETLE. 



( A doretus umbrosus Fab. ) / — y 



This destructive beetle, first known locally as the "rose bug" and 

 the " Japan bug," made its appearance in and about Honolulu in the 

 autumn of 1891. The pest attracted widespread attention throughout 

 the islands because of its vicious attack on the roses, which up to that 

 time since the early days of their introduction had been luxuriant in 

 growth and profuse in flowers. This insect is first recorded from the 

 Hawaiian Islands b}^ Rile} r and Howard in Insect Life in 1893. Pro- 

 fessor Koebele in his reports as entomologist to the Hawaiian gov- 

 ernment for the biennial period ending 1897 and the 3 r ear ending 

 1898 records the insect as generally distributed and abundant on the 

 islands of Oahu, Maui, Kauai, and Hawaii. The beetle is, accord- 

 ing to Koebele, presumably a Japanese introduction, having been 

 brought to the islands in the larval state in the soil about the roots of 

 plants. 



In regard to the life history of the Japanese rose beetle, Professor 

 Koebele says: 



In Japan, where the temperature will probably allow the larvae but six months 

 active life, it may be that there it has but a single annual brood, and with the many 

 enemies present it is no wonder that the beetle in consequence can be called rare. I 

 have had the larvae barely out of the eggs in Honolulu, and yet in three weeks later 

 they were full-grown upon the decayed manure — not in general use in Japan — where 

 they doubtless fed upon decayed vegetable matter, as they also do on the islands. 

 The elongate small white eggs hatch in about seven to ten days, and the pupae give 

 forth the mature insects in from ten to fourteen days. Thus it will be seen that the 

 whole transformation takes from six to seven weeks in summer at Honolulu. 



While the Japanese rose beetle from the first showed a decided 

 preference for the rose, it has, however, gradually extended its range 

 of feeding, which now includes a great variety of food plants. Fol- 

 lowing the almost complete disappearance of the rose, the grape was 

 severely attacked. So general did the feeding habits of this pest 

 become that practically all dooryard and garden plants were to a 

 greater or less extent injured. The food plants recorded by Professor 

 Koebele are roses, orange, coffee, peach, guava, alligator pear, pome- 

 granate, Java plum, grape, umbrella tree, various palms, sunflower, 

 violets, Mexican vine, taro, and cane leaves. In regard to its food 

 plants in Japan, Koebele says: 



I met with the insects while collecting in the forests, where they fell in my 

 umbrella quite frequently during the summer around Yokohama, especially while 

 beating for the various Coccinellidae on oak, alder, and many other forest trees upon 

 which they feed at night. Not in one instance did I see a specimen in a garden. 



Since taro and sugar-cane leaves have already been recorded in the 

 list of food plants, it is not entirely a new departure to discuss this 



