The purpose of this listserve is to disseminate information and foster discussions regarding the inventory and monitoring of bees as well as their identification.
Squash bees (
Peponapis
and
Xenoglossa
spp.) are named after the plants they pollinate,
Cucurbita
spp., which include pumpkins, gourds, and of course, squashes. These bees are native to the United States, and occur throughout the United States, southeastern Canada, and into South America. Squash bees are similar in size to honey bees (
Apis mellifera
) but are more brownish-grey and white in color. When it comes to
Cucurbita
spp., squash and honey bees are the most important pollinators. However, squash bees synchronize their foraging activity with the bloom of their host plants -
Cucurbita
spp. bloom near dawn and close by late morning; likewise, squash bees emerge just before dawn and forage quickly, ceasing by late morning. When squash bees are abundant they thoroughly pollinate all available flowers, making subsequent visits by honey bees superfluous.
Squash bees make more contact with the reproductive parts of blooms and work faster than honey bees, and have an affinity for
Cucurbita
spp. whereas honey bees are generalist feeders and will move to competing blooms if the nectar reward is better. In fact, one study has shown that with a density of one squash bee for every 10 flowers, squash bees can efficiently pollinate
Cucurbita
spp. without the aid of honey bees. Squash crops are a half billion dollar industry in the United States, so it is important to assure adequate pollination of these crops. A current survey, Squash Pollinators of the Americas Survey, being conducted by the USDA Agricultural Research Service has found that Peponapis spp. are abundant and effective pollinators, and that this may be the first opportunity "for unmanaged, native non-social bees playing a key role for production of an agricultural crop at the continental scale." Research has also shown that
Peoponapis
spp. are abundant and perhaps the dominant pollinator of
Cucurbita
crops throughout much of their range. Interestingly, some species of
Peponapis
are expanding their ranges as humans have expanded the natural range of squashes.
Squash bees are solitary bees. Solitary bees usually build and live in individual nests rather than in a hive or with a colony of bees, while social or communal bees do live colonially in hives or bee communities.
Squash Bees
Peponapis spp., Xenoglossa spp.
Description:Squash bees are about the size of honey bees, but are more brownish-gray and white in color. They are also faster than honey bees. Male antennae in Peponapis spp. are somewhat shorter than in most species in the Eucerini tribe.
Life History:These bees are solitary ground-nesters, but are gregarious so prefer to nest in groups. Males dart between flowers in the morning searching for mates, and Peponapis spp. actually mate inside the flowers of Cucurbita spp. Each female digs her own nest - a vertical tunnel that is up to two feet deep ending with a loose grouping of individual chambers. Each chamber is provisioned with a nectar and pollen mixture and a single egg. Larvae hatch and turn into pupae. After a period of inactivity, adult bees emerge.
Habitat:Squash bees nest in the ground in fields near Cucurbita spp.
Distribution:Squash bees are found throughout most of the United States and southeastern Canada, south through Mexico and Argentina.
