The red milkweed beetle, Tetraopes tetrophthalmus Forster, is a univoltine cerambycid that feeds upon the leaves and flowers of common milkweed, Asclepias syriaca L. Adult milkweed beetles prefer to aggregate on milkweeds that have multiple inflorescences of large size. Males actively searched for females, often flying between host plants, and apparently do not locate females from a distance using long-range pheromones or vision, but rather land on milkweed stems arbitrarily, whether females are present or not. Males remain for longer periods, and so tend to accumulate, on milkweed stems that had female-biased sex ratios. We conclude that aggregation of T. tetrophthalmus is cued by host plant characteristics, but dynamically influenced by the sex ratio of conspecifics present on individual stems.
Species 1: Coleoptera Cerambycidae Tetraopes tetrophthalmus (red milkweed beetle)
Species 2: Gentianales Asclepiadaceae Asclepias syriaca (common milkweed)
Keywords: dispersal, mating
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