46 



ment (shown in PI. II, fig. 2) and appeared upon its surface. The 

 occurrence here of a small snail, Galba iiinbilicata, is of interest. A 

 very large species of mosquito with conspicuously banded legs, Psoro- 

 phora cilia ta, was found here. Though these aquatics and the ground 

 forms did not receive much attention, they are representative of wet 

 places. 



The presence of certain plants in this habitat bus determined the 

 occurrence of several species of animals. Thus the dogbane Apocy- 

 niim medium accounts for the brilliantly colored leaf-beetle Chry- 

 sochiis auratus, which feeds upon its leaves and roots. But the most 

 conspicuous feature of this habitat in August is the variety of insects 

 which are attracted by the flowers of the swamp milkweed. These 

 flowers may be regarded as so much insect pasture. A few butterflies 

 were observed, Papilio polyxenes being found in an Argiope web; and 

 on the flowers of the swamp milkweed were Papilio crcsphontcs, Bury- 

 mus philodice, Argynnis idalia, Anosia plexippus, and the honeysuckle 

 sphinx (Heinaris diffiiiis). Among the most abundant Hynieuoptera 

 were the honey-bee (Apis mellifcra) and the common rusty digger- 

 wasp (Chlorion ichnciiiuoneuni). Others were the carpenter-bee 

 (Xylocopa virginica)- and the bumblebees Bonibus fratermis and sep- 

 arafiis. On the flowers of the thistle (Cirsiinn) near this station, Bom- 

 btts pe^insylvanicus was also taken The giant fly (Mydas davatus) 

 was taken on the flowers of the swamp milkweed. Beetles from these 

 flowers were the spotted milkweed-beetles (Tctraopes tetraophthaUiius 

 and fenioratiis?) the flower-beetle BupJioria sepulcliralis, and, late 

 in August, great numbers of the soldier-beetle CJiaidiognatlius penn- 

 syhanicus. The Heiniptera found are equally characteristic, and in- 

 clude both of the common milkweed-bugs (Oncopeltus fasciatus and 

 Lygccus kalmii) and Lygus pratensis. Still other insects were present 

 on the milkweeds, preying not upon the plant, but upon its guests. 

 These were the ambush bug (P/iyniafa fasciafa) and the ambush 

 spider (Mismnena aleatoria), the latter being captured with a large 

 bumblebee (Bonibus separatus) in its grasp. It is thus quite evident 

 that this milkweed has an important controlling influence upon the in- 

 sects of this habitat at this season. Another abundant animal was the 

 chigger, a larval mite of the genus Tronibidium, whicli is brushed from 

 the vegetation by one's arms and legs. These irritating pests were so 

 abundant that to work with comfort in this region it was necessary 

 to powder one's clothes and body with flowers of sulphur. These 

 young six-legged mites are supposed to prey upon insects, as do the 

 adults. According to Chittenden ('06 14) chiggers are most abun- 

 dant in damp places and forest margins, and among shrubs, grass, 



