206 BRITISH ANTS. 



flowers of Chrysoplenium and Rosaceae 21 . Rayward observed D. 

 nigra attending the larvae of the Blue Butterfly (Lycaena bellargus) 

 at Folkestone on August llth and 12th, 1906 50 . 



Wakefield in 1854 saw this ant for days and nights together 

 he observed them working at midnight industriously occupied 

 in dragging to its cells the seeds of the common violet Viola 

 odorata) 1 *. Spencer noticed the same habit at Blackheath in 1859, 

 and he saw the ants bring out these seeds from their holes on fine 

 days in July 19 , and Lord Avebury also records the fact that they 

 collect violet seeds 31 . In 1903 Janet frequently found in nests of 

 Donisthorpea nigra near Beauvais seeds of Galium aparine* 5 . 



D. nigra is a hardy and courageous ant, and it leads an inter- 

 mediate life between those species which are subterranean in their 

 habits and those which spend most of their time in the open air. 



When its nests are disturbed the workers pour out and swarm all 

 over the intruder, and it engages in frequent combats with other 

 ants. It is a deadly enemy to Donisthorpea flava and remains of 

 the latter are constantly to be found in nigra nests. Forel mentions 

 a nest of Formica rufibarbis which he saw encircled and besieged 

 by thousands of D. nigra in Switzerland 25 . 



It is sometimes found in company with other ants, but these 

 cases are probably only accidental, being due to the gradual en- 

 croachment by nigra on the situations occupied by the other 

 species. 



Schenck states that it lives not seldom with other ants, for 

 example, flava under the same stone, or near each other in the 

 earth, or in the same earth-hill 10 , and I found a mixed nest of 

 flava and nigra under the same stone at Mickleham 39 on May 27th, 

 1900, and I subsequently pointed out " As it is unusual for these 

 ants to live together, they were probably encroaching on each other, 

 and eventually the one might exterminate the other." 54 



Barnes records that he dug up two dealated females of D. nigra 

 in a nest of Formica sanguinea at Wellington College on Septem- 

 ber 6th, 1902 40 , but it is probable that these females were only 

 sheltering in the earth after the marriage flight, and were not really 

 in the sanguinea nest. The workers of nigra, in common with 

 many other species, will lay eggs, more especially in queenless 

 nests, and it was generally supposed that these parthenogetic eggs 

 always produce males, but Reichenbach has shown that these 

 eggs will produce workers 41 Wheeler very ably commented on 

 this and some other known cases 42 and recently Crawley has 

 proved the same thing by several experiments with colonies in 

 captivity 58 . 



The pupae are usually enclosed in cocoons, but Mayr records 

 naked nigra pupae 15 , Janet found naked pupae in a number of 

 nests under large stones at Beauvais 44 , and I found them abundant 

 in a mound nest at Sandown, Isle of Wight, on August 7th, 1913 63 . 



