The tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), a devastating pest of tomato, invaded Tanzania in 2014. There is now a pressing need to determine the extent of T. absoluta infestations in tomato, other solanaceous crops, and wild plants of Tanzania, to support research and to develop pest management programs. In Sep and Oct 2015, we visited 15 randomly selected villages in 4 leading tomato-producing districts (Arumeru, Lushoto, Kilolo, and Mvomero) and sampled fields representing 9 solanaceous crops and weeds. Tuta absoluta was present in all 4 districts. Overall, in tomato (Solanum lycopersicum L.) T. absoluta established 1.0 ± 1.3 (mean ± standard deviation) mines per leaf and damaged 15 ± 15% of fruits; in eggplant (aubergine) (Solanum melongena L.) it established 0.3 ± 0.7 mines per leaf and damaged 0 ± 0% of fruits; in potato (Solanum tuberosum L.) T. absoluta established 0.17 ± 0.1 mines per leaf; and in 2 African nightshades (Solanum nigrum L. and Solanum americanum Mill.) T. absoluta established 0.02 ± 0.03 mines per leaf (fruits of the latter 2 were not sampled). Pepper (Capsicum annuum L.) and African eggplant (Solanum aethiopicum L.) were not affected by T. absoluta. We found 3 solanaceous weeds in the vicinity of T. absoluta-infested fields in Arumeru District: Solanum incanum L., Datura stramonium L., and Nicandara physalodes (L.) Gaertn. None of these species were infested by T. absoluta; however, the latter 2 were infested by Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), which has habits and larvae that resemble those of T. absoluta.