Nowadays, several chemicals are being assayed to control the proliferation of the ascomycete Ascosphera apis in honey beehives. The presence and growing of these fungi in bee larvae causes their death and as a result of this a reduction in the number of bees is appreciated in the colony, and this also produces important economic losses, not only for the apiarists, but also for the surrounding farmers by means of decreasing pollination. Diverse fungicides have been assayed with the aim of penetrating into the larvae to avoid the fungi development, and among them, carbendazim [methylbenzimidazol-2-yl carbamate] seems to be one of the most suitable chemicals to prevent the disease. To control beehive treatment and establish the therapeutic dose for the product, it is compulsory to get reliable procedures to evaluate the residues of the fungicide on larvae.