DONISTHORPEA. 185 



the ants of the genus Formica, the workers follow each other in files, 

 often using well-beaten tracks, and they never carry their fellows. 



In finding their way, they do not use their eyes, but rely on the 

 senses of smell and touch. 



Some species lead an out-of-door life, but others are very sub- 

 terranean in their habits, the workers seldom coming above 

 ground. 



The nesting habits of Donisthorpea are very diverse, some make 

 carton nests, and they live in holes in trees, in old tree stumps, in 

 roots, under stones, in earth mounds, in banks, and also under the 

 pavements and in masonry in the centre of towns. 



These ants are very fond of sweet liquids, but will devour small 

 insects, etc., and also collect the seeds of plants. 



They keep droves of Aphids and Coccids, pasturing them on 

 roots and stems of subterranean plants ; some species attend 

 Aphidae on plants and trees above ground, and also milk Lycaenid 

 larvae (the caterpillars of the " Blue " Butterflies). 



They build covered ways from their nests, and earthen pavilions 

 in which to shelter their plant-lice, etc. They even collect the eggs 

 of Aphidae, storing them in their nests during the winter, and when 

 these hatch, they carry the young plant-lice out and place them on 

 their proper food -plants. 



The colonies of Donisthorpea which are generally large, and often 

 very populous are founded by some species in the normal manner, 

 and by others, which are temporary social parasites, in one of the 

 abnormal methods. 



The fertile females, whose gasters are often enormously swollen 

 with eggs, are always surrounded by a court of workers, being 

 sometimes entirely covered by them, and the latter continually 

 follow their queen, feed and clean her, and carry away her eggs as 

 she lays them. 



Crawley and I have shown that the large -bodied females of this 

 genus lay eggs only a few days after fecundation, whereas the 

 temporary social parasites do not lay till the next year. 



The males being about the size of the workers, and sometimes 

 even smaller than the largest specimens of the latter, are consider- 

 ably smaller than the females, and are usually carried by them in 

 the air, when united, during the marriage flight. 



Escherich states that the normal period for the marriage flight 

 is July, and that it extends from the middle of that month to the 

 middle of August. But in England August is the principal time, 

 and these marriage flights sometimes commence as early as June 

 and continue till October, swarms during the latter month being 

 probably due to a second generation of the males and females. 



The workers in some species are nearly all uniform as regards 

 size, but in others both large and small specimens occur. 



The larvae practically occur in the nests throughout the year, 





