1974 ] 
Nutting, Blum , £sf Bales — Tenuirostritermes 
169 
separate slides in the form of discrete threads of frontal gland secre- 
tion which they had fired in the general direction of the ants. The 
volume of most of these shots was calculated from measurements 
made of the threads with an ocular micrometer under a compound 
microscope. Drawings to illustrate the variation of individual shot 
patterns were made with the aid of a camera lucida on the same 
microscope. The fate of a few ant victims was followed until their 
death and compared with that of normal ants which were isolated 
and allowed to die of starvation and desiccation. 
For the chemical analyses 600 living soldiers were placed in re- 
agent rc-pentane. Although it had been determined that the heads of 
the soldiers were the primary source of the odorous defensive com- 
pounds, 400 living workers were also extracted for comparative 
purposes. The extracts were concentrated under vacuum and ana- 
lyzed on a gas chromatograph interfaced to an LKB-9000 mass spec- 
trometer. A 4-meter column of 10% SP-1000 on 80/100 mesh 
Supelcoport operated isothermally at 65 °C was employed for all 
analyses. 
Results 
Foraging behavior. — T. tenuirostris forages in the open on the 
soil surface, mainly at night in southern Arizona as we have recently 
established, but it is also active on cloudy days, at least in western 
Mexico (Nutting, 1970). The following account of its general 
foraging behavior is a synthesis of observations made on about 12 
different groups at the Santa Rita Experimental Range during Sep- 
tember-October, 1972. 
Workers presumably open one or more access holes to the surface, 
but the soldiers are generally the first out and the last to return 
underground during bouts of surface activity. As many as 100 or 
more soldiers and very few workers may congregate within a 5- to 
10-cm radius of the hole prior to foraging. Little organization is at 
first apparent except that many of the soldiers may be standing on 
the alert with heads pointed peripherally. One or more discrete for- 
aging columns eventually emerge from such unorganized, milling 
masses, perhaps after the soldiers are joined by a critical number of 
workers. Once in motion, columns up to six workers wide move 
quickly in an ant-like manner, and show very tight trail-following 
behavior. While soldiers move out with the workers, they eventually 
take up stations at 1- to 2-cm intervals on either side of, and ca. 1 cm 
