Alligatorweed, Alternanthera philoxeroides (Mart.) Griseb., is one of

the most serious invasive weeds. It is also one of the first listed 9 key invasi

ve plants in the Chinese State Biodiversity Report. Flea beetle, Agasicles hyg

rophila Selma & Vogt, a host-specific natural enemy, controls the weed success

fully

 in the world. Morphological characters and behaviors of A. hygrophila were

desc

ribed in this paper. The eggs are arranged in 2 parallel rows, the longitudinal

axis of each of the eggs of each row being oblique to the midline between the ro

ws. Successful completion of the incubation period is dependent on sustained hig

h humidity. Larvae preferred the succulent apical growing tips and leaves of the

 1st, 2nd, 3rd and 4th pairs. The young larvae attack and destroy the lower epid

ermis of the leaf. The 2nd_ and 3rd_stage larvae consume more leaf tissue. Pupat

ion begins after the 3rd_stage larva has satisfied its feeding prerequisite. The

 insect chews a circular hole into the internode, pulls its body through the hol

e. The ingested stem tissue from the entrance hole is masticated and regurgitate

d to form a plug. Adults begin to mating in 6d after emergence. The female ovipo

sits on the underside of an apical leaf.

喜旱莲子草(Alternanthera philoxeroides (Mart.) Griseb.)是一种水陆两栖的重要

外来入侵种，是中国国家环保局公布的首批9种重要外来入侵植物之一。莲草直胸跳甲Aga

sicles hygrophila Selma & Vogt是目前控制喜旱莲子草最有效的天敌昆虫。对该虫的形

态特征和行为习性作了描述。卵块成“八”字形，孵化需要高湿度的保持；幼虫有趋嫩性，

幼龄幼虫一般取食叶片的下表皮，2、3龄幼虫取食量很大；老熟幼虫在茎秆上咬一个圆形的

洞，进入茎秆中化蛹，并咀嚼咬下的植物组织，吐出后塞住洞口；成虫羽化6 d后交尾，雌

虫产卵于顶叶的背面。