A List of the Bees of the Genus Perdita Smith

The present list includes all the known species of Perdita, the genus being confined to North America, and only v>ell developed in the ariJ southwest. The South American insects referred by Friese to Perdita belong to Parafriesia, a genus scarcely separable from Calliopsis. The Old 'Vorld genus Nomi01'des has the closest possible superficial resemblance to Perdita, but is structurally quite distinct, having much in common 'vith I-I alictus. The species of Perdita are mostly very small, and practically all are oligotropic, confining their visits to a single genus, or to a few closely allied genera. Occasionall~, specimens will he found on plants of quite di,·erse families, and this seems especially to occur when the proper food plant is not yet in bloom. l\iost of the species occur in late summer and autumn, but there is quite a series of spring-appearing forms. I have never taken any species both in spring and summer, but l\Ir. Yicreck took P. phacelicr in l\Iay and June, and P. pectidis in April and lVIay, at Alamogordo, New l\Iexico, these being previously known as September bees. It is not knmYn whether the September brood hibernates and reappears in spring, or there are two generations in the year.