We found the first (spring) generation ofPsilopa leucostoma(Meigen), a leafminer, develops onAtriplex patulavar.hastata(L.) Gray growing in sheltered and fairly humid locations, frequently in irrigation canals. At this time, the dry soil under unirrigated sugarbeets and the lack of a protective foliage canopy in young plants make sugarbeets a poor host until 6–8 wk after adults are present in warmer and more humid areas.