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US Fish & Wildlife Service FieldNotes

PAHRANAGAT NWR: Pahranagat Pollinators

Region 1, October 31, 2012
Digger Bee on thistle.
Digger Bee on thistle. - Photo Credit: n/a
Sweat Bee on goldenrod.
Sweat Bee on goldenrod. - Photo Credit: n/a
A fly that resembles a bee to gain the protection from predators.
A fly that resembles a bee to gain the protection from predators. - Photo Credit: n/a
Common Buckeye on a sunflower.
Common Buckeye on a sunflower. - Photo Credit: n/a
Blister Beetle on a sunflower.
Blister Beetle on a sunflower. - Photo Credit: n/a

By Bruce Lund

With the recent dramatic decline in honeybees around the United States, interested parties in agriculture, horticulture, and wildlife are scrambling to learn if and how native pollinating insects might be utilized to support (or even replace) the pollinating services of honeybees.

Due to the popular interest in this topic, I volunteered to initiate a pollinator survey at Pahranagat National Wildlife Refuge last summer.

When Europeans began immigrating to the New World, they brought over crops and animals they knew how to grow and raise. Having been used for centuries as pollinators and for honey, honey bees were transported to the New World early on and have been the reliable crop pollinator workhorse since those early days. Honey bees escaped into the wild and are so abundant that they are the most common pollinator one sees on wild flowers. However, there are many others and I hoped to discover the diversity that could be seen at Pahranagat.

From April into October, I conducted three surveys on four different survey lines and documented 42 different pollinating insects. The most abundant and diverse pollinator I found were bees and wasps, followed by butterflies, flies, and beetles.

The surveys opened up a whole new world for me, discovering and photographing wasps, bees, flies that look like bees, and more. As I continue this work into a second season, I hope to engage students in the Youth Conservation Corps in running surveys. I would also like to continue photographing the diversity of pollinators, to create interpretive exhibits, and to present one or more fall programs in the local community about our discoveries.

Here are a few of the pollinating insects seen in 2012:

Digger bees were one of the most common and industrious pollinators seen. Thistle flowers were common targets of these 3/8 inch long bees. Adults jam their faces into flowers and extend their tongues to drink high energy nectar for themselves. They collect pollen in wide hairy “baskets” on their hind legs to provide food for their larva (and pollinate other flowers as the bees fly to different plants) which are kept in underground burrows.

Sweat bees are small at just a quarter-inch long, but their bright metallic green thoraxes make them among the most strikingly colored of the pollinators. One is commonly seen getting nectar from goldenrod flowers. These bees nest in soil or rotting wood in small social groups with the daughters helping their mothers raise young bees through the nesting season.

Many flies that look like bees gain protection from predators (like birds) that don’t want to get stung. Like bees, the adult flies feed on nectar and pollen gets caught in their hairs and is transferred to other flowers. Heliotrope flowers are one of a variety of landing sites. Ironically, the fly larvae are parasitic on the larvae of ground nesting bees, wasps, and beetles. To get their eggs onto these other larva, the female fly finds the access holes of their host insects and flips her eggs inside where the fly larva hatches, crawls to the bee larva, and settles in for a long winter feed.

Everyone loves butterflies for their bright colors, and they are also pollinators on many kinds of flowers. While the adults drink nectar, butterflies lay their eggs on plants which their caterpillar larvae eat for their food.

Less well recognized as pollinators, a few kinds of beetles eat pollen and nectar as their adult food, and their legs and bodies get dusted with pollen which they carry to other flowers. One type is the inch-long adult blister beetle (they eject an irritating fluid that causes blisters) which may be seen feeding on a sunflower. Their eggs are laid on plants, hatch into tiny larvae that crawl up into a flower to wait for bees to land. The larva scrambles aboard the bee and drops off when the bee goes into its ground burrow where the beetle larva proceeds to eat the pollen stored for the larval bees and then eats the larvae bees.

Bruce Lund is a member of the Friends of Desert National Wildlife Refuge Complex group in southern Nevada.

Contact Info: Harry Konwin, 702-515-5494, harry_konwin@fws.gov