The nitidulid species,Carpophilus mutilatusErichson,C. hemipterus(L.),C. freemaniDobson, andC. obsoletusErichson, responded to their aggregation pheromones during a 17-mo study in a California date garden. The pheromones were dramatically synergized by volatiles from fermenting whole-wheat bread dough; pheromones alone attracted only 1.0–29% as many beetles as the combinations with dough, and dough alone attracted only 0–2.9% as many as the combinations. Unbaited controls caught noCarpophilus. C. mutilatuswas the most abundant species, and individual trap catches were as high as 63,500 per week. Cross attraction was significant in some cases, especially forC. mutilatusresponding to the pheromones ofC. hemipterusandC. obsoletusbut was minimal compared with responses to the species’ own pheromones. The pheromone ofC. lugubrisMurray was also tested, but noC. lugubriswere detected in the date garden. Two additional nitidulid species were caught consistently:C. (Urophorus) humeralis(F.) andHaptoncus luteolus(Erichson).C. humeralisresponded significantly to all of the pheromones but especially to those forC. hemipterus,C. lugubris,andC. obsoletusin combination with dough.H. luteoluswas attracted only to the dough. Adult beetles were present in the dates on the ground throughout the year, but flight activity, as measured by trap catch, occurred erratically. All species had an intense period of flight activity in April and May, following a winter with favorable rains and an abundant food supply. This flight terminated abruptly when dates spilled to the ground during harvest and were hydrated bya rain storm. Flights ofC. freemani,C. obsoletus,C. humeralis, andH. luteoluswere more frequent in summer than forC. mutilatusorC. hemipterus.Flight activity during December and January was low for all species, but there was great variability in patterns of flight activity. The use of these pheromones is discussed in relation to pest management.