Notes on Japanese Species of the Genus Hypera Injurious to Legun inous Pastures

Studies on Insects Injurious to Pastures in Hokkaido, No.V

Abstract

This paper deals with Japanese weevils of the genus Hypera injuring leguminous pastures. In the course of the present investigation s the following five species have been known to occur in Japan.
1 Hypera nigrirostris (FABRICIUS)
2Hypera viciae (GYLLENHAL)
3 Hypera runzicis (LINN'E)
4Hypera basalis (Voss)
5 Hypera-adspersa (LINN'E)
1) Hypera nigrirostris (F.)
This species is the most important pest of pastures feeding principally on clover. In Japan its distributional range is restricted to the northern part of Honshu and Hokkaido.
The winter is passed in the adult stage. In the spring the beetles feed on the leaves of clover and alfalfa. The females lay their eggs in May, June and July. The larvae feed on new buds and axils of the host plants, and they pupate during June and July. The new adults emerge in late June to August. These beetles teke food actively for about two months, doing considerable damage to leguminous pastures. There is a single generation a year.
2) Hypera viciae (GYLLENHAL)
This species occurs only in certain zones on the coast of Hokkaido. It is less important than the preceding species. The adults feed on leaves and flowers of several kinds of vetches (Vicia sp.) in July and August. The adults often feed ravenously on the leaves of clover.
3) Hypera rumicis (L.)
This species has been known to be found on rhubarb (Rumexsp.) in fields of alfalfa in Hokkaido, but it has never been known to attack alfalfa.
4) Hypera basal is (Voss)
This species is widely distributed in Honshu, Shikoku and Kyushu but not in Hokkaido. The adult is found on chickweed (Malachium sp., Stellaria sp.) in fields of clover in Hcnshu, but it has never been known to attack clover.
5) Hypera adspersa (L.)
This species was once found on parsley (Oenathe sp.) in Gifu. The biology of this species has not yet been exactly known.
The adults of the Japanese species excluding H. adspersa are distinguished by the following key:
1) Scale strongly forked 2
-Scale slightly forked or not 3
2) Elytra with black markings on 1st to 3 rd intervals laterally. Honshu, Shikoku and Kyushu. Host plant: chickweed H. basalis
-Elytra clothed with green scales, without black markings. Hokkaido. Host plant: clover and alfalfa H. nigrirostris
3) Scale slightly forked. Hokkaido. Host plant: vetch H. viciae
-Scale not forked. Hokkaido. Host plant: rhubarb. H. rumicis