1901.] NATURAL SCIENCES OF THILADELPHIA. 441 



life, as uoue of several subject to the same experimeut lived more 

 than six days. 



The Stenamma fulvum jylceum also meet extreme cold with impu- 

 nity. At about 50° F. , or 10° C. , they become sluggish, remaiu- 

 iug almost or quite motionless in their usual attitudes. I froze a 

 two-queen colony fur twenty-four hours, the thermometer going 

 down to 23° F. , or 5° C. On gradually thawing the ants, all 

 survived, including callows but two days old, and the fi'ozen 

 pupa', larvte and eggs developed perfectly later on. Another 

 small colony was frozen continuously for five days, the thermome- 

 ter going down to 15° F., or 10° C. The queen and all ihe 

 workers survived thawing, but a fifth of the workers died soon 

 after, and the queen, who had previously laid eggs almost daily 

 for five months, laid no egg thereafter for eighteen days. 



It is probable that these ants, being highly thermotactic, seek 

 the deeper, warmer recesses of their nests in the ground in autumn, 

 and there hibernate until the warmth of spring draws them toward 

 the surface. 



The color of these ants manifestly deepens with age. The newly 

 hatched callows are translucent amber. The brown tint of the 

 adult first begins lo appear on the dorsal side of the largest seg- 

 ments of the abdomen. Some of the majors have already this 

 beginning of brown coloration before they pass the pupa stage. 

 The head, which is throughout life darker than the thorax, takes 

 on color next after the abdomen. In three or four mouths the 

 young worker has the color of an adult, but very old ants, queens 

 as well as workers, attain deeper shades of brown with passing 

 years. The males are fully colored, a glossy jet black, even before 

 leaving the puj^a stage. 



I have not yet the data from which to draw conclusions concern- 

 ing the longevity of queens and workers, though I have those in 

 my nests that are certainly over one year old. The shorter-lived 

 males have furnished me the following record relating to their 

 longevity : 



Longevity Table for 20 males, i^resumahly the issue of queens* eggs. 



«. Swarmed September 17 from roadside colony, iso- 

 lated with queen of another colouy in a Petri cell, 

 lived 5 daj's. 



