Social Insects. 29 



of neuters or workers, which are all females arrested in develop 

 ment; (2) of males; and (3) of fully developed females or 

 queens. All the males and females acquire wings, which are, how 

 ever, torn off after the marriage flight, and a number of queens are 

 supported in each formicary. In some of the species the workers 

 are uniform in appearance, while in others they exhibit great dif 

 ferences in size and structure. As already stated, the workers or 

 neuters are generally divided into two classes, viz., the ordinary 

 small kind, and a second kind with much larger head and man 

 dibles, and called soldiers. Bates has shown that in the Sauba 

 ant of South America ((Ecodoma cephalotes) there are two forms 

 of the large-headed neuters, one with hairy and the other with 

 polished head. 



LENGTH OF LIFE IN ANTS. Lubbock's experiments have shown 

 that in some species the mature workers will live from one to six 

 years, and the females even much longer, the life of the males 

 being very ephemeral and lasting but a few days or weeks. He 

 kept a female of Formica fusca for thirteen years. 



MIGEATIONS. There are two kinds of ant migrations. The 

 swarming of the sexes takes place usually in the afternoon or to 

 ward evening on warm or sultry days,, and it is remarkable 

 how very general, over a wide extent of country, the same 

 species will begin to fill the air on some particular day. 

 Species of the genera Lasius, Formica, Tetramorium, and Cre- 

 mastogaster, particularly, often form dense swarms or clouds, 

 ascending high up into the air. These swarms of ants have 

 sometimes been known to be so dense and persistent that it was im 

 possible, over large areas, to put the foot down without crushing 

 dozens of the insects which have been swept together in vast piles. 

 A case is on record of a large species covering the surface of the 

 water at sea to a depth of six inches, and for a distance of six 

 miles. This congregating in such vast swarms is due to the uni 

 form and simultaneous hatching and development in all the col 

 onies over a large extent of country. 



The migrations of the sexes are really love excursions, whereas 

 the migrations of the workers, which take place in vast bodies at 

 times, are a result of undue multiplication, and are intended to 

 improve the condition of the surplus progeny and found new 

 colonies. 



MYRMECOPHIL^S. A most interesting lecture might be devoted 



