Blue Dacnis lay clutches of two to three whitish or greenish-white eggs that are marked with a dull grey that forms a wreath at the large end of the egg (Isler and Isler 1987). The female Blue Dacnis builds the nest, while the male stands guard (Skutch 1962b). The nest is usually a deep cup (almost pouch) composed of fine fibers and seed down compactly matted (Ihering 1900). The female incubates the eggs alone, and the male will sometimes bring her food (Isler and Isler 1987). In Skutch (1989) data from 12 hours of observation of a female Blue Dacnis are provided. The female incubated the eggs in 20 sessions in times ranging from 11 to 55 minutes, with the average time being 23.6 minutes. The breaks in between incubation periods lasted from 6 to 18 minutes, with an average of 11.7 minutes. The incubation period is unknown, and the nesting period is 13 days (Skutch 1989). The parents divide the nestlings among themselves, feeding those in their charge (Isler and Isler 1987). In one case an unmated male that acted as a sort of helper to a pair of parents (Skutch 1962b). The unmated individual was observed helping protect the nest from a mirror with the two parents, and also helped the parents feed a female nestling, that the male parent also fed (Skutch 1962b). It is recorded breeding in Trinidad in March, June, and July; in Brazil in December; and in Costa Rica in May (Isler and Isler 1987).