the beautiful red poinsettia plant popular at Christmas is poisonous and has been known to kill dogs who chewed on them. They also come in white and variegated colors. Nightshade is a deadly plant.
they are helpful not harmful to plants
a cicada is harmful because they take pollen from plants
Depends.. 95% of all microorganisms are helpful. Most protists are usually helpful.
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Ladybird's favorite food is Aphid (greenfly/blackfly) which attack plants. Ladybirds are a beneficial insect and gardners and Horticulturalists encourage them.
Marsupials are helpful to humans in that they keep grasses and plants at manageable levels. They are only harmful to humans when they get too close and scare the animals.
it can be helpful or harmful
Bacteria or bacterium are the microscopic single-celled simple plants some are harmful and some are helpful. Bacteria constitute a large domain of prokaryotic microorganisms.
sometimes they are helpful and harmful.
Bacteria can be both harmful and helpful
Sandpaper is both helpful and harmful.
parasite