164 



He finds, however, that on white flowers, white spiders occur gen- 

 erally, that on yellozv flowers, yellow spiders occur, and also that 

 upon flowers of colors other than white and yellow, such as purple, 

 pink, and blue (p. 93), white spiders predominate. 



ATTID/E 



P/iidippus sp. 



This jumping spider was taken Aug. 12 (No. 34) on the common 

 milkweed, Asclepias syriaca, along the railway tracks (near Sta. 

 I, a), and when captured had in its jaws fragments of what seemed 

 to be Diabrotica 12-punctata Oliv. ; but as the fragments were lost 

 during the process of capture, this determination was not made 

 certain. 



ACARINA 



Trombidiid.e 



Trombidium sp. Harvest-mites. Chiggers. (PI. XXI, figs. 1 and 2.) 



These are the immature six-legged stage of a mite or mites which 

 when mature have eight legs. The voung are parasitic on insects 

 (Banks, Proc. U. S. Nat. Mus., Vol. 28, pp. 31-32, 1904) ; the 

 adults prey upon plant-lice and caterpillars; one species also eats 

 locusts' eggs. 



These mites were very abundant on the prairie north of Charles- 

 ton (Sta. I), and became such a pest that relief had to be sought 

 in a liberal application of flowers of sulphur to our legs and arms, 

 as is recommended by Chittenden ('06). 



INSECTA 



Odonata 



LlBELLULIDiE 



Sympetrum rubicundulum Say. Red-tailed Dragon-fly. 



This dragon-fly was taken in the prairie grass zone (Sta. I, g) 

 Aug. 8 (No. 4.) It is one of our commonest kinds. The nymphs 

 live in small bodies of standing water. The adults forage for small 

 insects in open places, along hedge rows, and in open forest glades. 

 For the habitats of dragon-fly nymphs, reference should be made 

 to Needham (Bull. 68, N. Y. 'State Mus., p. 275. 1903). William- 

 son ('00, pp. 235-236) has observed robber-flies carrying this species, 

 and has found this and other species of dragon-flies in the webs of 

 the spider Argiope. 



