Q. I have been hearing about the plight of honeybees and was wondering if there was anything I could be doing in my garden to help? Are there particular plants they prefer?

A. Honeybee populations have declined at an alarming rate. Researchers participating in the Mid-Atlantic Apiculture Research and Extension Consortium (including faculty from Penn State's entomology department) studying the phenomena of colony collapse disorder found that roughly one-third of honeybee colonies died out during the winter of 2006-07. They theorize that no one factor causes colony collapse, but rather the combination of several factors led to it, including varroa mites, diseases such as the recently discovered Israeli Acute Paralysis Virus, pesticides and poor nutrition.

This decline also affects other pollinators (other bee species, butterflies and moths, some beetles and flies, bats and hummingbirds), and it has been well documented in Great Britain and the Netherlands, too. The loss of pollinators could have significant consequences for the world's food supply.

There are a number of steps you can take in your own yard to attract pollinators and keep them safe while they are visiting. One of the most important things you can do is to plant a diversity of flowering plants to provide the pollen and nectar they depend upon. A combination of flowering trees and shrubs and perennial and annual flowering plants provides a range of flower shapes, colors, sizes and fragrances. Adding some native plants to the mix will make your yard more inviting to native bee species such as mason bees. Try to have something in bloom from early spring through late fall so there is a constant supply of pollen and nectar.

Limit pesticide use as much as possible, especially insecticides, and choose the least toxic product that will control the problem effectively. Insecticidal soap and horticultural oil have no residual activity once the spray has dried, and botanical insecticides have very short residual activity because they break down very quickly on exposure to sunlight. If you have to spray, do so in the evening after bees have returned to their nests. Avoid spraying any crop when it is in bloom.

Other ways to draw pollinators are to offer a shallow source of water such as a pot saucer and to stop mowing a strip of lawn and allow weeds to grow there. This provides a protected place for pollinators to lay eggs and pupate, while the flowers on the weeds offer pollen and nectar.

Trees and shrubs

• Red maple (Acer rubrum)
• Butterfly bush (Buddleia davidii)
• Buttonbush (Cephalanthus occidentalis)
• Redbud (Cercis canadensis)
• Summersweet (Clethra alnifolia)
• Hawthorn (Crataegus spp.)
• American holly (Ilex opaca)
• Apple, crabapple (Malus spp.)
• Black gum (Nyssa sylvatica)
• Sourwood (Oxydendrum arboreum)
• Cherry (Prunus spp.)
• Black currant (Ribes)
• Black locust (Robinia pseudoacacia)
• Blackberry, raspberry (Rubus spp.)
• Linden (Tilia spp.)
• Blueberry (Vaccinium spp.)
• Arrowwood (Viburnum dentatum)

Annuals and perennials

• Anise hyssop (Agastache foeniculum)
• Root beer hyssop (Agastache rupestris)
• Ornamental allium (Allium spp.)
• Butterfly weed (Asclepias spp.)
• Aster (Aster spp.)
• Borage (Borago officinalis)
• Cosmos (Cosmos spp.)
• Crocus (Crocus spp.)
• Purple coneflower (Echinacea purpurea)
• Viper's bugloss (Echium vulgare)
• Globe thistle (Echinops ritro)
• Joe-pye weed (Eupatorium spp.)
• Fennel (Foeniculum vulgare)
• Blanket flower (Gaillardia grandiflora)
• Snowdrops (Galanthus spp.)
• Perennial geranium (Geranium spp.)
• Sunflower (Helianthus spp.)
• Lavender (Lavandula spp.)
• Blazing star (Liatris spp.)
• Four o'clock (Mirabilis jalapa)
• Mint (Mentha spp.)
• Bee balm (Monarda spp.)
• Catmint (Nepeta spp.)
• Basil (Ocimum basilicum)
• Oregano (Origanum spp.)
• Russian sage (Perovskia atriplicifolia)
• Garden phlox (Phlox paniculata -- powdery mildew-resistant varieties such as 'David')
• Mountain mint (Pycnanthemum incana)
• Sage (Salvia spp., annual and perennial varieties)
• Pincushion flower (Scabiosa columbaria)
• Goldenrod (Solidago spp.)
• Germander (Teucrium spp.)
• Thyme (Thymus spp.)
• White clover (Trifolium repens)
• Verbena (Verbena spp.)
• Zinnia (Zinnia spp.)