Abstract: Ophraella communa LeSage, a kind of hexapod specially feeding on ragweeds (Ambrosia artemisiifolia L.) was found in Shaoguan in Guangdong province. The investigation showed that there were 129 egg clusters, 121 larvae, 20 pupae and 10 adults simultaneously clustered in one midly-injured ragweed, from which it may be concluded that O. communa had the living habit to be in clusters. O. communa finished its life cycle including laying eggs, hatching, developing and maturing before the ragweed finished its reproduction. So far, O. communa was only found to specially feed on ragweeds.