1915] Andrews: Survey of Lake Butte Des Morts Bog 
211 
in great numbers. A few tree toads were seen industriously cap- 
turing small flies and leaf hoppers. 
The turtles, which were not very common, sat looking in the 
sun on the top of some floating log, or concealed themselves in 
the water far out on the marsh. 
SUMMARY 
The bog has its characteristic animals and plants, as the forest 
the meadow, or the roadside have theirs. The dragon flies are 
the most conspicuous animals. Their hunting ground may be 
divided into horizontal zones, each characterized by the presence 
of a few particular species. One reason for this is that the dragon 
flies prey upon one another — the larger individuals eating the 
smaller ones. 
May-flies and mosquitoes were not seen where the dragon flies 
were numerous, though they were very common in other parts of 
the bog where there were no dragon flies. 
Certain species of insects common in July were seldom seen in 
August. They either completed their life cycle in this short time, 
or died because they were unable to resist adverse conditions. 
As the bog dries up, certain species of snails migrate to deeper 
water so that many present in July were gone in August. The 
chimney holes of the crayfish were not very numerous until in 
August. 
The greatest activity of the bog animals occurred between the 
hours of 12 noon and 2 p.m. Before eight in the morning and 
after five in the afternoon snails and a few beetles were about the 
only animals that could be seen. 
BIBLIOGRAPHY 
Jackson, Hartley, H. T. 1914 The Land Vertebrates of Ridgeway Bog, 
Wisconsin: Their Ecological Succession and Source of Ingres- 
sion. Bull. Wis. Nat. Hist. Soc., 12, 4-54. 
Pearse, A. S. 1913, 1914 Observations on the Fauna of the Rock Beaches 
at Nahant, Massachusetts. Bull. Wis. Nat. Hist. Soc., 11, 8- 
34; 12, 72-80. 
Shelford 1913 Animal Communities in Temperate America. xiii+ 362. 
Zoological Laboratory, 
University of Wisconsin. 
July 1, 1915. 
