148 
Psyche 
[Vol. 89 
that “different communities (colonies) have different grades of hos- 
tility” (p. 218). Studying Coptotermes acinaciformis, Howick and 
Creffield (1980) similarly report inter-colony variance in degree of 
aggression. 
The mechanism by which termites recognize non-colony mem- 
bers, and the associated stimuli for aggressive response, are not 
understood. Termites of some species quickly discriminate between 
colony-mates and foreigners; other species seem oblivious to “ali- 
ens”. Certain treatments have been shown to interfere with recogni- 
tion or aggressive behaviors: water washes (Andrews 191 1), chilling 
termites to immobilization (Dropkin 1946; Howick & Creffield 
1980), and laboratory rearing (Nel 1968). Unpigmented immatures 
of some species appear immune from attack (Andrews 1911, Sands 
& Lamb 1975). Dudley and Beaumont (1889a) postulated that col- 
ony members bear like “odors”, and that they can thereby differen- 
tiate colony-mates from foreigners. This idea of what is now termed 
colony-specific recognition pheromones is still viable (reviewed by 
Stuart 1970), perhaps involving cuticular hydrocarbons as recogni- 
tion cues (Howard et al. 1978, Blomquist et al. 1979). The degree of 
intraspecific pheromone variation, the environmental components 
of response, and the mode of aggressive stimulus remain unknown. 
Workers may be particularly useful as a capable, defensive unit in 
termite-termite encounters because they are the numerically domi- 
nant caste and although they are accompanied by soldiers on forag- 
ing forays, they are vulnerable to predation and competition while 
foraging. Termite mounds and arboreal nests have few exposed 
openings, and any which exist are guarded, usually by soldiers. In 
contrast, worker foragers cannot rely on nest protection, and their 
armada of soldier escorts may be insufficient to stay competitors. 
Mandibulate soldiers are normally in low proportion relative to 
workers (Haverty 1977). The ratio of termite soldiers to workers in 
Nasutitermes is relatively high (Haverty 1977), but the soldiers have 
vestigal mandibles and their chemical sprays are apparently not a 
complete defense against other termites. Soldiers may be especially 
proficient at repelling ant and vertebrate attacks (although workers 
may assist, eg. Eisner et al. 1976), while worker castes are adept at 
joining with soldiers to defend resources against other termites. 
