1965 ] Creighton — Macrotnischa subditiva 285 
the largest colony contained 145 workers, the smallest one only 
twelve workers. It appears, therefore, that the colonies of subditiva 
are always small and seldom, if ever, pleometrotic. 
Two captive colonies were established in February 1965 and it 
was soon apparent that subditiva is a very easy ant to maintain in 
artificial nests. It appears to be omnivorous, since the captive colonies 
rarely refused anything edible, but it has a strong preference for 
insect food. The captive colonies ate termites, fruit flies, house 
flies, crane flies, mosquitos, dermestid beetles, crickets, caterpillars 
and various moths and butterflies. With the exception of adult 
sawflies and stoneflies, which they plainly disliked, although they 
ate them, they accepted this varied insect diet without hesitation. 
They are one of the few ants which the writer has studied that 
would eat cut-worms. Their favorite food appeared to be the 
larvae of buprestid bettles. The ant larvae were mostly fed by 
regurgitation but, on occasion, bits of insect tissue were placed in 
their jaws. 
In the captive colonies the rate of egg-laying averaged out to 
slightly less than three eggs per day. The eggs hatched into larvae 
in about 30 days and these transformed into pupae in about 23 days. 
The pupal period was about 19 days. The pupae darken extensively 
after 14 days and at emergence are so deeply colored that there is 
no callow period in the strict sense of the term. These newly 
emerged adults can be told from their older nestmates but this is 
by no means easy for the color difference is slight and largely con- 
fined to the lower surface of the body. It is usually easier to tell 
a “callow” by its actions for, during the first two or three days 
after emergence they take little part in the nest activities. The 
pupal exuvium is pulled off in long strips by the workers. Two or 
three will often work together at stripping off the exuvium, which 
they apparently eat. During the stripping the emerging imago often 
assists the process by bending its body from side to side. 
It appears that subditiva produces and matures brood throughout 
the year. The writer has taken nests of subditiva from the middle 
of October to the middle of March and these have invariably con- 
tained brood. With the exception of two male pupae this brood has 
been free of sexual forms, hence it seems likely that under ordinary 
conditions only worker brood is produced during the winter months. 
It may be added that subditiva has no trouble bringing brood through 
in artificial nests. During the time that the captive colonies were 
under observation the population of one of them more than tripled. 
