Learn more about how to support and promote Pennsylvania’s pollinators by referencing the Pennsylvania Pollinator Protection Plan.

Checklist of Pennsylvania Bees

CPR member Shelby Kilpatrick has compiled an updated Checklist of the Bees of Pennsylvania, bringing together museum specimens and current observations to provide county-by-county records of the over 400 native species of bees in Pennsylvania. Shelby's checklist also provides information you can reference to learn about and identify the six bee families that occur in Pennsylvania, including many pictures.

Checklists of species diversity can help to inform the public of areas of conservation concern when those species are rarely or no longer detected in places they used to occur. While we now have a comprehensive list of bee species in Pennsylvania, data is still lacking on the diversity of other pollinators of Pennsylvania, including butterfly, fly, and beetle species that are also important members of natural and managed Pennsylvania ecosystems.

Conservation of Pennsylvania's Imperiled Pollinators

With the recent listing of the Rusty-Patched Bumble Bee (Bombus affinis) on the Federal Endangered Species List, pollinator conservation has become a popular topic of public discourse and action is required for species that are especially at risk in North America. A recent collaborative effort between the USFWS and the USDA: Natural Resource and Conservation Service compiled the information of five 'critically imperiled' pollinators within Pennsylvania, along with the counties where conservation actions would be most effective and steps that can be taken to actively conserve them. Below are general overviews of the species and conservation actions we each can take to conserve them in Pennsylvania, along with PDFs provided by the USFWS/USDA-NRCS collaboration. If you would like more detailed information about any of these imperiled pollinators, it is available upon request to Dr. Natalie Boyle (Natalie.Boyle@psu.edu).

Frosted Elfin (Callophrys irus irus)

The frosted elfin is a small, gossamer-winged butterfly with brown forewings and “frosted" hindwing tails. Loss of specific food plants and critical habitats has reduced the species' range, leaving only a few known populations scattered in three areas of eastern Pennsylvania. The frosted elfin requires dry, open woods, forest edges, and/or scrub areas. As these habitats have become lost due to anthropogenic habitat changes, frosted elfins have become reliant on man-made, “managed" areas like utility rights-of-way, railroad corridors, and recreational trails. They require ongoing availability of large patches of habitat that include larval host plants (like yellow wild indigo and wild lupine) and adult nectar plants (various flowering plants).

Priority Counties for Conservation Actions
Centre, Chester, Huntingdon, Lackawanna, Lebanon, Lancaster, Monroe

Recommended Conservation Actions
Since the frosted elfin requires dry, open wooded areas, creation and ongoing management of these areas is crucial to the recovery of the species. Actions such as converting agricultural land adjacent to woodlands to a forested edge, converting dry forest to more open habitats (i.e., reduce canopy cover), and/or enhance native meadows to include wild lupine and blue wild indigo, can be pivotal to maintaining a landscape that can support abundant frosted elfin populations.

Rusty-Patched Bumble Bee (Bombus affinis)

In 2017, the Rusty-Patched Bumble Bee (RPBB) was the first insect in North America to be federally listed as endangered by the US Fish and Wildlife Service. Populations of the RPBB have been steeply declining due to habitat change, non-native pathogens, and widespread pesticide use, resulting in only 5% of the populations remaining within their previous range. RPBB males and workers have a patch of red within a band of yellow hair on their abdomen. They can be found in a variety of habitats as long as those areas have consistent and abundant floral and nesting resources.

Priority Counties for Conservation Actions
Although RPBB has not been seen in Pennsylvania for over 7 years, conservation actions that increase nesting and foraging resources will benefit other imperiled pollinators and will provide habitat if RPBB ever returns to its native range throughout PA.

Recommended Conservation Actions
Habitat requirements for the RPBB include abundant foraging resources and nesting resources. Since RPBB are generalist pollinators, recommended seed mixes should provide abundant and diverse floral resources from April to September. Successful nest sites generally occur in undisturbed areas (i.e., the edges of forests, fields, grasslands, or meadows) near abundant and diverse nectar sources.

Yellow-Banded Bumble Bee (Bombus terricola)

The Yellow-Banded Bumble Bee (YBBB) is a medium-sized bumble bee with a distinct yellow band on the front of the thorax and on their abdomen. While it has not yet been federally listed as endangered by the US Fish and Wildlife Service, their range and populations are noted as declining as of 2019. They can be found in a variety of habitats as long as those areas have consistent and abundant floral and nesting resources.

Priority Counties for Conservation Actions
All counties in Pennsylvania are priority counties for YBBB conservation actions.

Recommended Conservation Actions
Similar to the Rusty-Patched Bumble Bee, the YBBB requires habitats with abundant foraging and nesting resources. Recommended seed mixes should provide abundant and diverse floral resources from April to September. Successful nest sites generally occur in undisturbed areas (i.e., the edges of forests, fields, grasslands, or meadows) near abundant and diverse nectar sources.

Monarch Butterfly (Danaus plexippus plexippus)

The monarch is a brush-footed butterfly with distinctive orange and black wings covered in white spots. Historically common east of the Rockies, the monarch's population has been reduced by over 90% in the last 30 years. The biggest contributor to these precipitous declines is the loss of larval host plants and nectar sources throughout its range. The monarch relies on milkweed as a host plant for their larva, laying eggs on the underside of leaves to hatch and feed on the milkweed as they mature. In Pennsylvania, monarchs generally arrive on their migration in mid-April and leave in early October to return to their overwintering grounds in Mexico.

Priority Counties for Conservation Actions
All counties in Pennsylvania are priority counties for monarch conservation actions.

Recommended Conservation Actions
Given that the primary cause for the monarch declines is the loss of habitat with floral resources and larval host plants, creating or enhancing native meadow areas that provide these resources is crucial to help reverse these declines. Planting at least two species of milkweed, preferably common milkweed (Asclepias syrica) and swamp milkweed (A. incarnata), as well as various native nectaring resources in an open and grassy area. Mowing these areas down to 6 inches once in the spring is also recommended. Using late-winter mowing on a 3-5 year patchy rotation will also help to maintain the meadow at various stages of regrowth.

Regal Fritillary (Speyeria idalia)

The regal fritillary is a butterfly with large orange and black wings. The species' range and abundance has been decimated due to lack of habitat providing abundant food resources. Although once common throughout the tall-grass prairies and other disturbed areas of Pennsylvania, there is now only one remnant population of the regal fritillary in the state, located at Fort Indiantown Gap. Their habitat requirements include violets for their larvae, nectar plants for adults, and native warm-season bunch grasses for protection.

Priority Counties for Conservation Actions
Adams, Dauphin, Huntingdon, Lebanon

Recommended Conservation Actions
Conservation actions that would be optimal for the regal fritillary include the creation and management of upland prairie habitat with native, warm-season bunch grasses and wildflower mixes that include violets. Crops and hayfields can be converted permanently or seasonally. Mowing needs to include the removal of thatch to prevent smothering the violets in the spring. Burning is not recommended as it greatly destroys the grass cover and nectar plant cover.