Ancylandrena larreae (Timberlake 1951)

Ancylandrena larreae Timberlake

This is a Larrea oligolege of the Colorado and Mojave deserts of southern California, ranging from San Diego and Imperial counties to the Owens Valley and east to Lordsburg, New Mexico. It is a spring species, with the principal flight in March and April in the lower deserts, May in the higher areas.

Zavortink (1974), in his revision of the genus Ancylandrena, describes this species fully, figures its critical characters, and maps its distribution as known to him. He regards it as oligolectic on Larrea, and states that all but two of the 58 males and 80 females examined by him (which bore flowers records) were from this plant, the exceptions being single males taken on Dalea greggii and Prosopis julifiora. He reported that the species was abundant during April 1969 in the Chemehuevi Valley west of Havasu Lake, California. On 21 April individuals were common on Larrea tridentata during the 1.5 hours following sunrise, less abundant from 1.5 to 4.5 hours after sunrise, absent from 4.5 to 5.5 hours after sunrise, and rare during the half hour preceding sunset. No attempt was made to collect at this site before sunrise, during the late morning, or during the afternoon, and it is not known if A. larreae was active at these times. Zavortink summarized the distribution as known to him as the deserts of southern California, southern Nevada, and Arizona. We have incorporated the localities recorded by him in our map (Figure 4) and have added localities from our surveys. The most significant of these is Lordsburg, New Mexico, where a male was taken between 0445 and 0600 on 25 May 1973 by Juanita M. (Mrs. E. G.) Linsley. This collection extends the range from the Mojave and Sonoran deserts well into the Chihuahuan Desert, just west of the Continental Divide.

We encountered A. larreae at most of our March and April Larrea sample sites in California and Arizona. However, it was most abundant in Palm Springs, Riverside County, California, in early April. Half-hour samples yielded 229 pollen-collecting females, two nectar-drinking females, and 68 males. The females first appeared at the Larrea flowers at sunrise or shortly afterward (air temperature 16° C) and reached a peak in numbers about mid-morning (Table 13). A few scattered individuals (19) were captured while taking pollen between 0930 and 1429. The peak of male activity about Larrea flowers coincided fairly well with that of females, as judged from our samples, and only four examples were taken between 0930 and 1429.

When the females first begin to collect pollen as the sun rises, they work the flowers on the outside of the plant on the side exposed to the sun. As the temperature rises, they move inside the plant and onto the shady side. Their flight also becomes faster, assumes a zigzag pattern, and they move a considerable distance between flowers, sometimes visiting but a single flower on a plant. Males, when they first appear, drink nectar and remain on the flower for up to half a minute. They then assume a fast, irregular cruising flight about the plants, pausing only occasionally, and then briefly, for nectar. No “mating” encounters were observed.

Ancylandrena larreae, the creosote bush ancylandrena, is a species of mining bee in the family Andrenidae. It is found in Central America and North America.