46 



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

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

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

 phora ciliata, 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 has determined the 

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

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

 sochus 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 cresphontes, Bury- 

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

 sphinx (Hemaris diffinis). Among the most abundant Hymenoptcra 

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

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

 CXylocopa virgimca) and the bumblebees Bombus fraternus and sep- 

 aratus. On the flowers of the thistle (Cirsium) near this station, Bom- 

 bus pennsyh'anicus was also taken The giant fly (Mydas clavatus) 

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

 flowers were the spotted milkweed-beetles (Tetraopes tetraophthalmus 

 and femoratus?) the flower-beetle Buplioria sepulchralis, and, late 

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

 sylz-auicus. The Hemiptera found are equally characteristic, and in- 

 clude both of the common milkweed-bugs (Oncopeltus fascia tus and 

 Lygccus kahnii) 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 fPhymata fasciata) and the ambush 

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

 bumblebee (Bombus 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. x\nother abundant animal was the 

 chigger, a larval mite of the genus Trombidium, which 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 

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

 adults. According to Chittenden ('06 : 4) chiggers are most abun- 

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



