Predation by the anthocorid Tetraphleps galchanoides Ghauri on different stages of the hemlock woolly adelgid, Adelges tsugae Annand, was studied in laboratory. The results showed that the feeding of the adult and nymphal anthocorids corresponded to the Type II Holling functional response model. However, there was intra-interfere response on the adelgids. For the same stage of the anthocorid, there was higher daily predation at higher prey densities than that at lower prey densities. When given a choice of different stages of the prey, there was no significant difference in selection among the prey stages at the lowest prey density; however, there was significant difference when the prey stages were at the middle or high density. At the middle prey density, the anthocorid nymph prefers to feed on the adeligd egg and first instar nymph, whereas the anthocorid adult prefers to feed on the 4th instar nymph and adult. The potential of T. galchanoides for biological control of the hemlock woolly adelgid was discussed.
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