7S Journal of Kntomoloy) ami Zoology 



HYMENOPTERA 



The Yellow aiul Black Mud-dauber, Sceliphron serrillii Le- 

 peletier.-This interesting dauber is common along all of the streams 

 in the vicinity of Laguna Beach. The elongated mud cells about 

 one inch long are built singly or placed side by side in series of 

 from two to four and the whole covered with a continuous layer 

 of mud completely ol)literating the outlines of the individual cells. 

 The cells were commonly ijlaced on the undersides of large rocks 

 or boulders in the near vicinity of the fresh water streams and 

 often at the mouths of the canyons near the ocean. The nests 

 were stored chiefly with yellow and brownish-gray crab spiders. 



In the cells and attacking the larvae of the mud-daubers was 

 often found the maggot of a tachina fly, which proved to be 

 Pacliijaphthnlmua tioridoisix Townsend . The adults of this most 

 interesting fly escaped from the masonry cells by the expansion 

 and retraction of an inflatable bladder-like organ in the front of 

 the head (ptilinum?) which was used to moisten the mud and then 

 scrape it away. Adults confined in glass vials were easily observed 

 to continually endeavor to work their way through in this manner. 

 Not all of the ffies appeared to possess or to use such an organ, but 

 whether or not this is a sexual characteri.stic was not determined. 



The fire ant, SolenopsiN geminata Fab., was perhaps the com- 

 monest ant in the vicinity of the laboratory. During July the 

 ants were swarming from their ground nests in great numbers. 

 The workers are small, entirely reddish or with small rounded black 

 abdomens, the winged females are reddish throughout while the 

 winged males are black. 



• Determined liy J. M. Aldilch. 



