Nature Bulletin No. 12   April 28, 1945
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Superintendent of Conservation

****:EARTHWORM

Most people think of earthworms only as food for robins and bait for 
fishing. They are called "fishworms", "angleworms", and 'I'night 
crawlers". By digging in moist, rich soil, one can usually find several 
per square yard. They also may be found at night, using a flashlight 
with red cellophane over the lens, because earthworms come to the 
surface at night to feed on dead leaves or blades of mowed grass. Their 
"saliva" is strongly alkaline and softens such vegetable matter so they 
can digest it. They have no eyes nor ears but are very sensitive to touch 
and light. Red light does not bother them but they cannot endure the 
ultraviolet rays in daylight, which paralyzes them.

In the morning, after a heavy rain, large numbers of earthworms will be 
found on sidewalks and the ground surface, where they came for air to 
escape drowning. If they do not succeed soon in crawling back into 
their burrows, they die.

There are many species of earthworms. The largest, the true "night 
crawler", was imported into this country.--probably in earth around 
shrubs and bulbs.  Twenty-two species have been found in Ohio, 10 of 
them some of the 19 species native to Denmark.  Thirty-seven species 
have been found in the British Isles. Some are quite small. Some live 10 
or more years. They are composed of a large number of segments, or 
rings, each having four pairs of little bristles that enable them to crawl; 
and on the surface there are numerous small holes to the tiny kidneys 
and other organs. The mouth end is larger; the tail end flatter.

Earthworms are the most important animals affecting the structure and 
fertility of soils, particularly forest soils. They excavate many channels 
in the soil, sometimes 8 feet down into the subsoil, which lets rainwater 
penetrate. They bring the excavated material to the top and deposit it 
around the mouth of the burrow as "castings. " Therefore, they are 
mixers of the soil, as well as channellers. Charles Darwin found as 
much as 36,000 pounds of castings per acre. Other scientists have found 
from 75 to 300 earthworms per square yard of forest soil. Consuming 
the dead leaves, blades of grass and other litter -- in the fall they pull 
quantities of these down into their burrows -- they are also reducers of 
surface litter.

Many foresters are coming to believe that when we plant trees we 
should also plant earthworms.