The frequency and extent of predation on hummingbird nestlings by wasps of the family Vespidae is not well known. Among the 14 hummingbird accounts in the Birds of North America series, there are no documented records of vespids killing adults or young of any species of hummingbird. A further literature review returned only four reports of vespid predation of bird nestlings, supporting the conclusion that this type of predation is rare or underreported. On 29 July 2018 I observed the predation of two Black-chinned Hummingbird (Archilochus alexandri) nestlings by four to six yellowjackets (Vespula sp.) in the Highlands area of the Boise foothills in Idaho. I first became aware of the hummingbird nest, about 2 m off the ground on the lower branch of an ash (Fraxinus sp.) tree overhanging my ground-level deck, on 20 July. Later in the day I photographed the adult female hummingbird on the nest from a discreet distance (Figure 1A and B). I checked on the nest regularly with binoculars and photographed it in late morning and early evening, when sunlight fell on the nest. The adult female was observed on the nest from 20 to 24 July. On 24 July, I observed nestlings for the first time. I last photographed the nestlings on 28 July in the late morning, mid-afternoon, and early evening (Figure 1C, D, E, and F).