March 1958 Species Account, Pipistrellus hesperus. p.4. July 14 Aqua Caliente Hot Spr., San Diego Co., Calif. Al Beck and I spent about an hour about from 8 to 9 P.M. netting these bats as they came in to drink over these pools here. I was successful only 11 times but 4 escaped after their initial capture. Al did somewhat better. There were a good number of bats, perhaps 70 bats. All of the 17 we caught were lactating females, Al said. Three subsequently died and were prepared as specimens (535-587). July 15 We continued our netting activities over the open water here again this evening. I worked over a very small pool that had been cemented in to serve as a bath. (Beck worked on the larger swimming pool nearer the main buildings. Together we got about 55 of this species as well as several other bats. saved. I prepared the crippled and dead (584-91). These were frozen and prepared later. Although I can't didn't always identify correctly the bats as I caught them I think that the other species were caught mainly later in the evening after 8:30 or so. July 16. Temco Mines, 700+ ft., Imperial Co., Calif. succeeded in shooting one of these bats that was night-roosting in the old corrugated iron building the north side of the valley here, in which we camped.