University of Maryland Extension

Pollinator Basics

Butterfly caterpillars can consume a lot of foliage in this stage, but they make up for it with their beauty and pollination services when they transform to adults.

Pollinator Photos   

What is pollination? 

The transfer of pollen from the male organ to the female organ of a flowering plant – is essential to life on earth, for without pollination most people and non-human animals would not have enough food. Over 90% of all known flowering plants, and almost all fruits, vegetables and grains, require pollination to produce crops. Happily, there is a pollinator volunteer work force that does this job for us: over 100,000 species of invertebrates, mostly insects, and over 1,000 species of vertebrates. Since one out of every three bites of food we eat each day requires pollination, we are indebted to the myriad creatures that perform this critical service.

Why is pollination essential?

Pollination is as essential to the production of food crops as sunlight, rainfall, and fertile soil. Pollinators help plants reproduce and in return, flowering plants produce food for pollinators in the form of nectar, a highly nutritious sweet fluid. As pollinators feed and fly about the garden, pollen grains stick to their bodies and limbs, and are rubbed off on female flower parts as the insects go about their business. Not only do pollinators boost the productivity of crops in this way, but they also help ensure the reproduction and survival of many flowering plants.

What are the four major groups of insect pollinators?

There are four major groups of insect pollinators: bees and wasps, beetles, butterflies and moths, and flies. Some are generalists, and visit many flowering plants, and others are specialists that concentrate on a single plant (e.g. yucca moths). All insect pollinators undergo complete metamorphosis: egg, larva (caterpillar, grub, or maggot), pupa, and winged adult. The appearance from one stage to the next changes dramatically, and it is important to recognize pollinators at each stage to help preserve them in your garden.

European honeybees are the "queen" pollinator species, but Maryland is home to at least 400 species of native bees that are essential to plant reproduction and food production.

University of Maryland Honey Bee Lab 
US Geological Service Bee Inventory & Monitoring Lab

Besides insects, what else pollinates plants?

Certain vertebrates, such as bats, hummingbirds, and even Rover crashing through your garden, may also act as pollinators, although not to the extent of insects. Bats don’t see well but have a keen sense of smell; they forage at night and are attracted to large, white or pale night-blooming flowers with strong, fruity scents. Pollen dusts their foreheads as they feed on nectar by thrusting their long tongues deep into blossoms, and this pollen is transferred to the next flower visited. Hummingbirds love vivid colors, such as red, purple/red, orange and pink, but are not particularly drawn to fragrances. These mighty little birds will feed up to 8 times an hour and are important pollinators of brightly colored, tubular-shaped flowers. They are often seen hovering before and feeding on sages, fuchsias, honeysuckles, nasturtiums, columbines, jewelweeds, and bee balms.

What is threatening pollinators?

Any practice that potentially creates an imbalance in the natural ecosystem may impact the pollinator biodiversity on which much food production depends. Of particular concern are:

  • Habitat loss and fragmentation: pollinators need a variety of native flowering plants in addition to introduced flowers to provide nutrition specific to their needs, as well as adequate food supplies throughout the growing season. Land development, elimination of native flowers and weeds, and planting only a few species of plants reduces resources and suitable nesting sites for pollinators, leading to reduced pollinator populations. Fragmentation of habitats increases the distance migratory pollinators must travel between areas providing food and shelter along their routes, adversely impacting survival for insects such as monarch butterflies.
  • Pesticides: broad-spectrum pesticides are a major threat to pollinators, both directly from unintentional poisonings, and indirectly from habitat reduction when native forage plants are destroyed with herbicides.

Additional Resources

Compiled by Chris Sargent

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2020. Web Accessibility