Ceratina dallatorreana , Friese is native to the Mediterranean region, where both sexes are present. The first bees appeared in the upper Sacramento Valley of California in 1949 and the species has since spread southward to the lower San Joaquin and Santa Clara Valleys. The life history in California is reconstructed by using the structure and contents of the nests, the immature stages, and certain anatomical features of the females, including the amount of wing wear, contents of the gut and spermatheca, development of the ovaries, presence of follicular relics, and the condition of the fat body. The species reproduces primarily by thelytokous parthenogenesis, but rare instances of insemination are detected and 1 male has been collected. Considerable variation in color is present and may be the result of automixis. At least 2 generations a year occur and the adults overwinter in solitary burrows. The nests of the bee are small and have a water-repellent lining which is apparently derived from glands on the second and third sterna. Preference for weedy plants as sources of food and nesting media has contributed to the success of the bee in an area of intense agricultural activity.
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