40 THE ARGENTINE ANT. 



THE LARVA. 

 (PI. IV, B, C.) 



The larva when first hatched is not distinguishable from the egg, 

 without the assistance of a magnifpng glass. For a time after 

 hatcliing the body is considerably curved, the cephalic end being 

 almost in touch with the caudal end, but as development progresses 

 the larva assumes more and more of a straight form. The curvature 

 is not entirely lost, however. 



A recently hatched larva, measured with the compound microsco])e 

 and eyepiece micrometer, was 0.49 mm. long by 0.32 wide. The fully 

 grown larvse (workers) average 1.7 mm. long by 0.66 mm. wide. The 

 largest one imder our observation measured 1.87 mm. by 0.765 mm. 



With the exception of slight constrictions of the body, the larvte 

 are incapable of motion, thus being entirely helpless and relying 

 altogether upon the ministrations of tbe attendant wori^ers. The 

 latter, however, perform their duties faitlifuhy, and care for their 

 charges with the greatest solicitude. They feed and groom the 

 young larvae continually and transport them from place to place 

 whenever necessary. In case of danger their fii'st instinct appears to 

 be to remove the young to a place of safety, and they readily sacrifice 

 their own lives in order to accomplish this. 



The larvae are fed often by the attending workers upon regurgitated 

 and presumably predigested food. There is nothing in the appear- 

 ance or actions of the workers which do the feeding to indicate that 

 they are different from those which perform other duties, or that 

 they are assigned to the particular and exclusive duty of being nurses. 

 The feeding of the larvae has several times been observed under a 

 magnifying glass, and is as follows: The larva ordinarily lies upon 

 its side or back. The attending worker approaches from any con- 

 venient direction, usually from one side or from the direction in wliich 

 the head of tlie larva lies, and, spreading her mandibles, places tliem 

 over the mouth parts of the larva, which are slightly extruded. The 

 tongue of the worker is also in contact with the larval moutli. Wliile 

 the worker liolds the body antl mandil)les stationary a drop of light- 

 colored, almost transparent fluid appears upon her tongue. This 

 fluid disappears within the mouth of the larva, but it can not be ascer- 

 tained to what extent tlie larval mouth j)arts are moved during the 

 operation, as they are obscured from view by the mandi})les and head 

 of the attending worker. Slight constrictions of the larval abdomen 

 during fec^ling are sometimes noticea])le, at other times not. The 

 time required for feeding a single larva varies from 3 to 30 seconds, 

 depending doul)tless on the hunger of the *'baby." The workers 



