Investigations into the biology and seasonal and specific variation of the most important pests(Cryptophlebiaspp. andNezaraspp.) of macadamia in Malawi are described. Details are given of the times taken for the eggs and larvae ofCryptophlebiaspp. to develop. The alternative hosts of both groups of pests are given.Cryptophlebialarvae are attacked in the nut by a number of parasites, which are listed and details of their frequency through the season are given. A maximum apparent parasitic percentage of 40% is recorded.Nezaraeggs are parasitized byTrissolcusspp. (Scelionidae), on average 74% of the eggs are parasitized. Nuts fed on byNezaramay develop infections by four fungi. The seasonal occurrence of the pests is given and the relationship of‐these with the susceptible stages of the crop is examined. The relationship of pest numbers with damage levels is investigated.