Earthworms are of great economic importance to man.
Beneficial aspects:
i. In
Agriculture: They are
regularly ploughing and manuring the soil. Their habit of burrowing and
swallowing soil makes soil loose, aerated and porous. Their worm castings make
soil fertile. Thus, they are regarded as friends of farmer.
iii. As food: They are used as food by fishes, frogs,
lizards, birds etc.
They
are used as food by many uncivilized people in many parts of world.
iv. In
medicine: They are used variously as medicine
for the cure of stones in bladder, jaundice, piles, sexual impotency etc.
v. In
laboratories: They are
universally used for dissections and for investigations in general and
comparative physiology, morphology and anatomy.
Harmful aspects:–
i.
Their burrows may cause loss of water
by seepage from irrigated fields and ditches.
ii.
As they make soil loose, It may leads
to soil erosion in sloppy areas.
iii.
Certain species may live as external
parasites of animals like frog.
iv.
Certain species may act as intermediate
host of parasites.
v.
Certain species become pests of
plants.