The black squash mirid, Pycnoderes quadrimaculatus Guérin-Méneville, 1857, was recently found feeding on chayote squash, Sechium edule (Jacq.) Sw. (Cucurbitaceae), under cultivation in Campo Grande, Veracruz, Mexico. Based on the economic importance of this plant in the region, research under laboratory conditions was initiated to study essential aspects of the biology (duration of life cycle and survival) and basic morphology of this pest insect. The duration of the egg, immature (instars 1–5), and adult stages lasted 14.2, 14.1, and 31 days, respectively. Elongated, slightly curved eggs, without respiratory projections, were inserted in the main and secondary veins of chayote leaves. All nymphal instars were yellowish to pale greenish with distinct black regions and black setae scattered over the dorsum, except for the hyaline to whitish and smooth first instar. Sexual dimorphism was not present in P. quadrimaculatus. The probability of survival for males and females feeding on chayote squash was estimated to be 100% at 3 and 21 days, respectively. Subsequently, survival decreased without significant differences between the sexes. This is the first report of aspects of the life cycle, morphology, and survival of P. quadrimaculatus.