﻿56 



"Numerous cases of mimicry and deceptive likeness to 

 surroundings are known to occur in the spiders belongin.^ to 

 Tlioviisiis and allied genera, and it may therefore be of some 

 interest to record an additional case which has recently come 

 under my observation in Custer County, Colorado. There is 

 a yellow-flowered umbelliferous plant — Ligustiami montaniini, 

 Benth. and Hook. — which is very frequent by the creeks, and 

 a careful search will reveal specimens of a yellow spider of 

 moderate size, seated in the slight depression in the middle 

 of the disc of the umbel, never more than one spider on a 

 single disc. These spiders also frequent the yellow blossoms 

 of certain species of Cruciferai growing in the same neigh- 

 bourhood ; and in all cases, when seated on the flower, 

 resemble it in colour so closely as to be quite unnoticeable 

 unless specially looked for. Now, whenever an insect settles 

 on the flower, the spider makes a spring and grasps its victim, 

 nor lets go again until he has made a meal of its life juices. 

 This afternoon I noticed a small Pamphila, allied to the 

 European P. co7nma, which did not fly off from the yellow flower 

 it was on when I approached. Wondering at this, I stooped 

 to examine, and certainly it was in the fatal grasp of a 

 yellow spider, and by that time quite dead. The flowers of 

 Ligusticum in this locality are much frequented by a pretty 

 beetle — Trichodes ornatus. Say,, and a prettier green Chrysis ; 

 but I have not yet observed the yellow spider to capture 

 these, though no doubt it does so. Mr. Wallis Kew has 

 recorded [Ent. Mo. Mag., vol. xxiii., p. 136) that Chrysis 

 ignita is preyed upon by a spider {Xysticus cristatJis) in 

 Lincolnshire. The sketch accompanying this note, although 

 rough, will give some idea of the appearance of the spider on 

 a Ligusticum flower." 



Mr. Weir said similar spiders were not at all uncommon on 

 flowers in England. There were several species closely 

 resembling the flowers on which they were sitting for the 

 purpose of obtaining their food. Mr. Tugwell had noticed 

 corresponding instances in the New Forest. Mr. Step had 

 seen a white species on the flowers of umbelliferous plants. 

 Mr. South had also frequently seen them in the umbels 

 of what was commonly called cow parsnip — Heracleum 

 sphondyliuin, L. 



