Best Practices for Forage and Habitat

Because the nesting and nutritional needs of different pollinator species are quite diverse, it is critical to ensure landscapes contain an abundant and diverse array of nesting opportunities and flowering plant species. We will focus on best practices to generate high quality nesting and forage habitat in different types of landscapes in this section. Information on how to minimize pesticide exposure can be found in the “Best Management Practices for Pesticide Use” section.

Depending on the species, wild bees can nest in chambers they excavate in loose soil, rotting wood, or in pithy parts of stems, or they can occupy existing cavities, such as those formed in and on the ground surface by rodents, trees or rocks. Approximately 30% of native bee species in the US nest in wood and stems, while 70% nest in the ground. Heterogenous and topologically variable habitats, such as forest edges or hedgerows, support a greater diversity of bee nest types. Nature can be supplemented by providing solitary bee nesting boxes, providing areas with exposed loose soil, leaving stems in place or in piles, and adding heterogeneity to home gardens and other managed lands. For more information, see resources for creating nest sites developed by the Xerces Society, the USDA National Agroforestry Center, or Penn State’s Center for Pollinator Research.

Pollinators depend on flowering plant species for their food. All species of pollinators (bees, flies, butterflies, moths, birds, bats, and others) use floral nectar as a source of carbohydrates. Bees in particular also collect pollen from flowering plants as a source of protein, fats, and other micronutrients. High quality and abundant pollen is critical for female bees to produce eggs and feed their brood.

Similarly, flowering plant species vary in their phenology (whether they bloom in the spring, summer and/or fall), the time of day that their flowers are open and accessible to pollinators, flower color, shape and scent, and the quantity and nutritional quality of the nectar and pollen. Thus, supporting a diverse and healthy pollinator community requires a mix of abundant and diverse flowering plants that bloom during the entire growing season. There are many resources available to help identify appropriate flowering plant species to include in different landscapes, which will be discussed in more detail below. Additionally, regional guides to pollinator plants and habitat restoration guides can be found at the Xerces’ Pollinator Resource Conservation Center and the Pollinator Partnership. For Pennsylvania, the Center for Pollinator Research has created a series of “Pocket Guides” for the best plant species to support a variety of pollinators.

Some pollinators require special food sources for their young. For example, most species of butterfly and moth caterpillars feed on the leaves of specific plants: for example, monarch caterpillars feed only on milkweed leaves, while swallowtail caterpillars feed on plants in the carrot family. A useful resource for butterfly and moth host plants butterfliesandmoths.org.

Non-native and ornamental plants can provide nutritional resources for many pollinators (see this publication from Penn State), but native plants tend to support a larger diversity of pollinators. Some non-native plants are noxious or invasive plants and should be avoided. For a list of these plants in Pennsylvania see the PA Dept. of Ag Noxious Plant List.

Issues related to restoring and maintaining landscapes to support diverse pollinator communities were recently discussed in a publication from Penn State, and summarized in the figure below.

Public interest in pollinator conservation has driven interest in the using solitary bee hotels to support wild or managed stem and cavity-nesting bee populations. Research into the design, utility and management practices for these hotels is ongoing. It is important to design and manage these thoughtfully to avoid introducing stressors.

In the next section, we discuss approaches to support pollinator communities in different contexts, including urban, roadsides and rights of way, agricultural and natural landscapes.

Gardens and green spaces in urban areas can support diverse pollinator communities; in fact, some studies have found that urban areas support more diverse communities than surrounding rural areas. Pollinators connect the public with the natural world by providing learning opportunities for K-12 students, ensuring pollination of fruits and vegetables in urban gardens and farms, and providing additional habitat and forage for pollinator communities in surrounding areas. Furthermore, simple changes to land management and land use practices can dramatically increase the habitat and forage available in urban areas, and thus lead to more community involvement and engagement.

In Pennsylvania, individuals can certify their pollinator gardens through the Penn State Master Gardeners and find many valuable resources for designing pollinator gardens on the PA Pollinator Garden Certification website. Penn State’s Center for Pollinator Research has planting guides for various groups of pollinators and information about building and maintaining nest sites for pollinators.

Additional resources, including sample garden designs, can be found in the Snetsinger Butterfly Garden website. Individuals are encouraged to visit local gardens and arboretums to learn more about pollinator gardens and native Pennsylvania plants, such as the Pollinator and Bird Garden at the Arboretum at Penn State, the Phipps Conservatory and Botanical Garden in Pittsburgh, Mt Cuba Center in Delaware, and Longwood Gardens outside of Philadelphia.

Individuals are also encouraged to advocate for Township or Municipal native plant or pollinator habitat ordinances that allow areas around homes and businesses to incorporate a variety of plant types (not just short grasses and lawns) as long as they are managed and not neglected. Such recommendations for “neighborly natural landscaping” are provided from Penn State Extension, and York County, PA recently developed a sustainable landscape model ordinance. Incorporated towns, cities and communities can become certified with the Bee Friendly PA program and with Bee City USA. Below, we provide specific recommendations for producing and maintaining pollinator habitat and forage in different types of urban areas.

Lawn Care. Traditional lawns with low-cut grass and with no flowering plants provide limited nutritional resources for pollinators. Homeowners and landscapers interested in alternative strategies for managing these areas, such as incorporating “natural” landscapes.

There are two million acres of lawn in Pennsylvania. The Pennsylvania Department of Conservation and Natural Resources offers technical assistance and resources for land owners interested in improving water quality and wildlife habitat, including for pollinators, through lawn conversion. This program also supports partnership development and funds eligible plantings.

Gardens, Landscapes, and Golf Courses. As noted above, there is a wealth of information on “neighborly natural landscaping” through Penn State Extension as well as how to create pollinator forage and habitat, including recommended plant lists, in gardens and larger landscapes on the Pennsylvania Pollinator Garden Certification website. Homeowners and landscapers can also obtain additional information through the Penn State Master Gardeners program, and through classes and workshops at the Phipps Conservatory and Botanical Garden. Briefly, recommendations for these gardens include:

• Grow a diversity of flowering plant species that ensure blooms throughout the season to provide nectar and pollen for diverse pollinators.

• Include host plant species that support butterfly and moth larvae (for example, milkweeds for monarch caterpillars)

• When desirable, use native plant species for your particular region, since these are generally best suited to support pollinators and to grow under typical Pennsylvania conditions. Information on sourcing native plants can be found at the Pennsylvania Native Plant Society.

• Avoid plant species that are considered invasive or noxious, and remove them if they are found on your property. A list of these plants is provided on the DCNR Invasive Plants List. Fact sheets with information on how to identify and control invasive plants are available at the DCNR NativePlants Website.

• Consider all types of flowering plants- trees and shrubs are particularly important for spring pollinators in Pennsylvania but vines, perennials, annuals and herbs also contribute to pollinator habitat, taking advantage of all areas and layers.

• Use an Integrated Pest Management (IPM) and Integrated Vegetation Management (IVM) approach to manage pests, diseases, and weeds (see Best Management Practices for Pesticide Use section). Mechanical and cultural methods are often very effective for addressing a variety of issues.

• Additional information on managing golf courses for pollinators can be found in “Optimizing Pest Management Practices to Conserve Pollinators in Turf Landscapes: current practices and future research needs” and in the Audubon Cooperative Sanctuary Program for Golf.

Urban Landscapes. Increasing green spaces in urban areas is associated not only with improved biodiversity but also with improved happiness and health of people living in these areas. Given the diversity of plant species that support pollinators, it is relatively straightforward to simultaneously increase green space and vegetation while improving pollinator habitat and forage. In particular, urban planners should:

• Choose species that have pollinator benefits when choosing yard and street tree species. A list of pollinator-friendly shrubs and trees can be found in this guide from Michigan State University.

• Remove invasive species and replace them with beneficial native plant species. Increasing plant diversity at the family, genus and species level will increase the biodiversity benefit of urban plants.

• During the public comment phase of public space design projects, work with municipal officials and design teams to specify plants that are beneficial to pollinators.

• Work with, or join city park volunteer “friends” groups to promote pollinator habitat restoration and creation. An example of such an organization is the Friends of Wissahickon.

Roadside and utility rights of way (ROWs) cover more than 10 million acres of land in the U.S. Pennsylvania has more than 40,000 miles of roads, making it one of the top 5 states in the nation for road miles. Roadside and utility ROWs are interconnected open spaces across diverse landscapes that can be managed to provide valuable habitat and forage for pollinators and other wildlife while also increasing aesthetic appeal. In 2015, the “Fixing America’s Surface Transportation Act” (FAST Act-Public Law 114-94, Section 1415) directed the Secretary of Transportation to use existing authorities, programs and funding to encourage State Departments of Transportation to facilitate efforts to improve habitat and forage for pollinators, outlined in this website.

ROWs can provide pollinators with habitats for feeding, reproduction, nesting, and overwintering in areas where these habitats are scarce. ROWs can also serve as refugia for rare plants and pollinators (see study from Penn State), and can provide “corridors” connecting different regions, which allow pollinators to access habitat resources across larger areas. Indeed, research has demonstrated that improving habitat on roadsides may increase the abundance and diversity of pollinators (see Xerces’ Pollinators and Roadsides guide). Roadsides can also be managed to both support pollinators and limit larger wildlife, such as deer: for example, reduced mowing can increase the abundance of flowering native plants while also reducing the amount of plants that are palatable to deer.

Managing ROWs is a challenging balancing act. Land managers need to control invasive species and support pollinator diversity while also addressing drivers’ and utility companies’ needs for visibility, safety, access, and erosion reduction. Moreover, not all ROWs are appropriate for supporting pollinator habitat—the effort and cost of installing pollinator habitat on the medians and sides of large, high-speed roadways may far outweigh the benefits, and roadsides are likely to contain residues of gasoline, motor oil, ethylene glycol, and salt and sand from winter roadside management. Finally, ROWs cover vast amounts of land, and thus it is most appropriate to consider management of selected locations and areas that are amenable to management and will provide the most benefit to pollinators.

Detailed information on managing ROWs for pollinators can be found in resources from Pollinator Partnership, the Xerces Society, Monarch Joint Venture and the US Department of Transportation Federal Highway Administration. Listed below are general guidelines to consider while developing plans to restore, maintain and expand forage and habitat for pollinators along ROWs.

• Build a coordinated network of individuals and groups interested in restoring and maintaining pollinator habitat. Volunteer groups can partner with Pennsylvania Department of Transportation (PennDOT) through the “Adopt and Beautify” Program, while businesses and corporations can partner with PennDOT through the “Sponsor a Highway” Program.

• The PennDOT Prelisting Pollinator Conservation Program is a voluntary, non-regulatory, and pro-active program to enhance and protect habitats for the yellow banded bumblebee, monarch butterfly, regal fritillary, and frosted elfin. These species are in decline and the Program aims to conserve them to avoid their listing under the federal Endangered Species Act. PennDOT conducts conservation actions such as conservation mowing, daylighting (removing tree canopy overgrowth so light reaches roadside habitat), and pollinator habitat planting. PennDOT's maintenance forces also work closely with the Pennsylvania State University to conduct roadside pollinator habitat research. PennDOT tracks the credits earned from providing benefits to the above species with the oversight of The Pollinator Work Group. This group is composed of representatives of federal and state agencies, conservation organizations, and the Pennsylvania State University, and it meets annually to review and advise the Program. More information can be found here.

• Evaluate potential sites and select an optimal site. Site selection criteria can include soil quality, proximity to other pollinator habitat, sunlight and water availability. It is also important to contact the U.S. Fish and Wildlife Service, Pennsylvania Field Office (ir1_espenn@fws.gov) to confirm that the site is not the habitat of an endangered or threatened species.

• Develop a restoration and management plan, with clear expectations for timelines, budgets and goals. Expect that the project will require a minimum of 3-5 years of sustained effort to become established, with additional time for maintenance.

• Include a selection of native plants that will provide nectar and pollen resources for pollinators throughout the growing season, and host plants for caterpillars of key pollinator species (such as native milkweeds for monarch butterflies).

• Develop strategies for controlling invasive plant species at appropriate levels (for example, the evaluation plan may state that up to 20% of plant species in the site can be non-native species before management is needed).

• Provide nesting habitat for pollinators, such as areas of bare soil for ground-nesting species and piles of thatch and dead wood for cavity-nesting species.

• Limit the number of times that ROWs are mowed to 0-2 times per year. Develop a plan that ensures the needs of stakeholders are met while optimally supporting pollinators. For example, mowing once a year in late fall may reduce negative impact on pollinators and reduce the presence of invasive species while ensuring visibility and safety. Alternatively, sections can be mowed at different times and to different heights, to ensure that some flowering plants and habitat are always intact.

• Use “Integrated Vegetation Management” and “Integrated Pest Management” approaches in order to reduce the use of herbicides and pesticides to maintain populations of invasive plant species and insect pests below threshold levels. Use methods that reduce the impact of pesticides on pollinators, e.g., minimizing drift, including non-pesticide buffer zones, spraying only a portion of the area. See information in “Best Management Practices for Pesticide Use” for more information. Information on IVM approaches can be found in PennDOT’s “Invasive Species Best Management Practices” publication.

• Develop an evaluation plan to document the success of the restoration and maintenance efforts.

• Celebrate the success of the management plan through social media and events and encourage other organizations to participate in similar efforts.

Approximately 75% of agricultural crops require or benefit from pollinators to set seed and produce fruit, and all crops can benefit from the arthropods that prey on or parasitize pest species, thereby reducing the negative impacts of these pest populations. There can be tremendous economic advantages to conserving and expanding populations of beneficial arthropods (managed and wild pollinators, predatory and parasitoid species) in agricultural landscapes. In Pennsylvania the estimated annual value of animal-pollinated crops is a quarter of a billion dollars (see the Introduction chapter), while in the United States the value is projected to be $34 billion, see this Penn State study. For information on the economic value of pollination services to crops in your area, visit Penn State’s Beescape website.

There are many strategies growers can use to enhance and expand forage and habitat for pollinators in their farms. Growers can install hedgerows or buffers on the edges of agricultural fields, meadows in areas that are not in production, and add flowering cover crops within agricultural fields. All of these have multiple benefits in addition to supporting diverse communities of pollinators and beneficial insects, including serving as windbreaks and limiting water and soil runoff and erosion. Detailed information on how to select and prepare sites, choose appropriate plant species, install pollinator habitat and forage, and maintain these sites can be found in the following documents:

• Regional guides to pollinator plants and habitat restoration guides can be found on Xerces’ Pollinator Resource Conservation Center and the Pollinator Partnership.

• USDA-NRCS/Xerces Society: Hedgerow Planting for Pollinators: Pennsylvania Installation Guide & Job Sheet

• USDA-NRCS/Xerces Society: Conservation Cover for Pollinators: Pennsylvania Installation Guide & Job Sheet

• Several programs are available to help growers install pollinator forage and habitat on their lands. These include:

  • USDA-FSA Conservation Reserve Program (CRP)

  • USDA-NRCS Conservation Stewardship Program (CSP)

  • USDA-NRCS Environmental Quality Incentives Program (EQIP)

  • USDA-NRCS Conservation Innovation Grants Program (CIG)

  • USFWS Partners for Fish and Wildlife Program

Pennsylvania has 124 state parks spanning 300,000 acres, 2.2 million acres of state forest, and 1.5 million acres of state game lands. However, approximately 70% of Pennsylvania’s forested land is privately owned, and thus it is critical that a broad range of stakeholders are engaged in efforts to protect pollinators in pollinator conservation, especially considering that no State agency has legal authority over Pennsylvania’s native terrestrial insects. This section provides recommendations for best practices to support and expand pollinator populations in larger tracts of relatively undeveloped forest and other natural habitats, including fields, wetlands, and riparian zones.

In addition to the information provided below, there are many comprehensive resources available that cover a broad range of management recommendations for pollinators on natural lands. The Pennsylvania Natural Heritage Program’s (PNHP) Habitat Management for Pollinators provides information on a variety of best management practices including ways to promote habitat variety to support all life stages of pollinators, maintain open habitats, control invasive plants, protect pollinator diversity and rare species, and select native and local plants for pollinators. Two comprehensive guides on habitat management for pollinators include the USDA Natural Resource Conservation Service’s Resources to Help Pollinators, and the Xerces Society’s’ Pollinators in Natural Areas: A Primer on Habitat Management. Research into pollinator-forest communities is ongoing. Some important topics include logging stand habitat, the influences of vegetative structure and factors driving floral abundance.

Incorporate Pennsylvania native plants, shrubs, and trees into wildlife habitat and reclamation efforts on public lands. Planting projects in forests and other natural habitats should include a variety of native trees, shrubs, grasses or forbs (wildflowers) to increase ecosystem functions and habitat diversity for pollinators and other wildlife. Native pollinators and other insects have evolved over time with native plants, and native plants are adapted to local climate and soil conditions. Furthermore, some native species can grow in very dry and nutrient-poor sites, do not need soil amendments, and rarely require fertilizer for establishment. Look for herbaceous and woody plants that will create continuous flowering throughout the growing season to ensure that nectar sources are present from spring through fall. Select a variety of plants with different flower colors and shapes that will bloom within each of the three growing seasons. When replanting disturbed sites, consider including an annual native like partridge-pea which can flower during the first growing season before other native perennials become established. As a general rule, maintenance activities such as mowing along roadsides and in rights of way, and burning or mowing in early successional habitats that support native flowering plants, should be conducted in a patchy manner and outside of the growing season when possible.

The Pennsylvania Bureau of Forestry Planting and Seeding Guidelines document provides recommendations on how to restore a disturbed site with native grasses, sedges, rushes, flowering plants, shrubs, deciduous trees, and conifers. The PNHP Habitat Management for Pollinators provides additional recommendations on how to select plants that will supply food to pollinators in their adult and immature life stages, and how to maintain pollinator habitats through management practices such as rotational mowing. The USDA Natural Resource Conservation Service’s Pollinator Biology and Habitat document provides simple guidelines on how to assess plant community diversity, select plants for a site, and design the planting layout to maximize attractiveness to pollinators. Additional guidelines can be found in Penn State Extension’s Forest Management and Center for Private Forests.

Prevent new invasive plant infestations and control existing ones. Some invasive plants can provide a temporary bloom of flowers for adult pollinators, but in the long term do much more harm than good by out-competing native caterpillar food plants and adult nectar plants and degrading other important habitat qualities. For a list of plants that are not native to the State, grow aggressively, and spread and displace native vegetation, see the DCNR Invasive Plants List. Fact sheets with information on how to identify and control invasive plants are available at the DCNR Wild Plants Website. Specific information on locations of invasive species and control efforts can be found at iMapInvasives.

Herbicides are necessary tools for land management and controlling invasive species, but these pesticides can have negative impacts on non-target species (including the plants that pollinators depend on for nutrition) and thus should be used as part of an Integrated Vegetation Management (IVM) approach. For more details, see the “Best Practices for Pesticide Use” section. Additionally, the following resources are comprehensive guides for controlling invasive plants and the use of herbicides in natural habitats:

• Safe Herbicide Handling in Natural Areas: A Guide for Land Stewards and Volunteer Stewards

• Upkeep and Maintenance of Herbicide Equipment: A guide for natural area stewards

• Weed Control Methods Handbook: Tools and Techniques for Use in Natural Areas

Deer Management. Deer browse on trees, herbaceous plants and shrubs can limit the food resources needed by local populations of adult and larval insects. Protecting pollinator nectar and host plants from excessive deer browse is a difficult challenge in many regions of Pennsylvania. Fencing and tree tubes are often necessary to protect investments in native plantings. Good overviews of how white-tailed deer shape their environment are available at DCNR’s Role in Deer Management: Conserving Pennsylvania’s Forests and Native Plants, in Penn State Extensions’ White-Tailed Deer, and in the USDA Forest Service Northeastern Area’s Impacts of White-Tailed Deer Over- abundance in Forest Ecosystems: An Overview. Two publications that provide more detailed deer management recommendations include The Natural Lands Trust’s Deer Management Options and the Cornell Cooperative Extension’s White-tailed Deer Wildlife Damage Management Fact Sheet.