Subsocial burrower bugs (Heteroptera: Cydnidae) provide unique opportunities to investigate evolutionary ecological questions regarding parental provisioning and family dynamics. Observations and marked nutlet-setting experiments in the field showed that Adomerus triguttulus females progressively delivered mint nutlets into nests harbouring nymphs under the litter. More than one female often attended nymphs, but not eggs, in a nest in the field. The number of nymphs aggregating in a nest with a single female was usually smaller than that in a nest with two females, suggesting the joining of different families and facultative joint parental care. There was a positive correlation between the number of nutlets delivered and the number of nymphs in a nest. The number of attendant females also affected the amount of provisioning; more nutlets were found for second-instar broods with more females. The effect of brood size on provisioning was confirmed for families under laboratory rearing. Maternal provisioning also varied with the developmental stage of offspring; second-instar broods received more nutlets than first-instar broods, with a temporal decrease in provisioning during the moulting of nymphs. Considering the growing evidence of food solicitation signals of young in subsocial insects, the observed finely tuned supply of food by the female could be induced by begging signals from the nymphs.