Environmental Engineering Reference
In-Depth Information
wasp backs down the burrow, pulling in the cicada. She lays a tiny egg on the cicada's body.When
the young hatches, it eats the cicada. Wasps also feed their young grasshoppers, beetle grubs, and
caterpillars. By preying on insects that destroy crops, wasps do humans a great service.
Black-crowned Night Herons:These birds choose to nest at the National Zoo. More than 400 wild
black-crowned night herons summer at the Zoo.They choose, ironically, to nest in trees around the
Bird House.You may see juveniles practicing their hunting skills in our wetlands ponds.The flock
arrives in March. Chicks hatch, several days apart, and parents bring them regurgitated food. Later,
they are fed whole small prey which is sometimes larger than the chick. Night herons preen and
sleep during the day. At dusk, they head for Rock Creek, and the Potomac and Anacostia rivers to
hunt.The species has a vast range—almost worldwide. Our night heron flock probably winters in
Central America. During this time, their nests sit empty, waiting for the flock to return. Black-
crowned night herons are messy, eating almost any aquatic animal. Under the trees where they nest,
you'll find fish bones, half-digested frogs, feathers, and crab shells. Night herons are also noisy, fill-
ing the air with a variety of interesting sounds.
Pollen in the Air: People and plant mating.When it's time to reproduce, some plants fill the air with
their male sex cells, pollen. The pollen sails the wind to fertilize female cells in far-flung flowers.
These plants produce millions of grains to increase their chances of success; yet only one grain
among millions reaches its target. Are you a victim of plant sex? When pollen lands on some peo-
ple, their bodies' immune systems go into overdrive—runny eyes, coughing, sneezing, suffering.
Flowers that are pollinated by animals have bright colors, showy petals, and seductive scents. But
flowers pollinated by wind have a different look. Their fluffy flower clusters are exposed to the
wind, and tend to be small, pale, and odorless.Wind needs no seduction.
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