Counting the Bristlesides, Sedgesitters, Leafwalkers

It’s National Pollinator Week! Scientists have been busy looking to see what pollinators live in State Parks. Here’s a first look at some of the early results.

NHP@Bumblefly
This is actually a fly! The bare-cheeked bumblefly is a very rare Syrphid in NY that mimics bumblebees and lives in old forests.  Photo courtesy of NYNHP.

In 2017 a cadre of NY Natural Heritage Program (NYNHP) biologists working under a long-standing agreement with State Parks began testing out sampling methods for a multi-year statewide Native Pollinator Survey (ESNPS) under the auspices of the Governor’s NYS Pollinator Protection Plan jointly administered by Department of Environmental Conservation and Department of Agriculture and Markets.

NHP_EasternCalligrapher
The eastern calligrapher (Toxomerus geminatus) is a very common species in State Parks all over the state.  Photo by Lindsay Dombroskie, accessed from iNaturalist.

The goal of the ESNPS is to determine the rarity of a wide array of native insect pollinators in non-agricultural habitats. NYNHP Zoologists honed in on the most important and vulnerable pollinating groups in the state, representing a wide variety of native insect pollinators such as bumble bees, mining bees, bee flies, longhorn beetles and flower moths.

NHP_Spider
Captured by a spider, a fate that befalls some flower-visiting flies.  Photo courtesy of NYNHP.

Between June 8 – October 3, 2017 on fair weather days, two biologists used sets of small painted bowls containing soapy water to trap pollinators (the insects mistake the color for a flower) in four different habitat types within each Park (see photo). The biologists also used insect nets to hand- capture pollinators (see photo), spending the better part of one day obtaining a snapshot of the Park’s pollinator community. The collections are the only way to document and identify most of the species.

 

Over the past winter the biologists then separated out the flies (Dipterans) from the bees and pinned these specimens so that they could be identified by fly specialists at SUNY Cobleskill (see photo). They focused on flies in one notable family, the Syrphidae – or Syrphids, known as the hover flies or flower flies.  Most of the remaining captured pollinators like the bees will be identified by experts at Cornell University as the project continues.

 

Preliminary results are in for the hover flies or flower flies that SUNY Cobleskill experts helped to identify. There are many different species or types of these flies and not anything like the plain black housefly. Some go by interesting names like Bristlesides, Sedgesitters and Leafwalkers. Many hover flies are mimics of stinging Hymenoptera (see photo) and known to be second only to bees in their pollinating prowess. This is because the adult flies feed on pollen and nectar to power their energy- intensive flight. In doing so, they help to pollinate a wide range of trees, shrubs and wildflowers in every conceivable habitat. At the same time, their larvae (the young stage) are predators of harmful insects such as aphids and adelgids. Many play an important role in aiding decomposition in aquatic and forest environments; in effect breaking down leaves, logs and other debris which then releases nutrients and builds soil.  In other words, Hover flies are very important to the health of our native ecosystems.

NHP@Goosepond
Look closely for the hover fly on a leaf at Goosepond Mountain State Park on September 28, 2017.  Photo courtesy of NYNHP.

A brand new hover fly field guide focusing specifically on northeastern North America will be published later in 2018 by a team of Canadian researchers. This will allow anybody with an interest to pursue these fascinating and colorful insects who will challenge your notions of what a fly is!

A few fun facts we learned about hover flies in State Parks:

  • Total number of Parks sampled: 22 (in all Regions)
  • Total number of different Syrphid (fly) pollinators: 50 species
  • State Parks with the highest diversity of hover flies (at least 7 different species plus more than 15 individual flies): Minnewaska, Thacher, Sunken Meadow, Letchworth, Taconic, and Allegany
  • Number of new species never before seen in the State, or were thought to be no longer in NYS: 5
  • Two out of every three individuals captured (67%) was a calligrapher (Toxomerus), small black and yellow flies whose larvae eat aphids (see photo)
  • Number of Parks with a species that mimic hornets (the rare eastern hornet fly (Spilomyia longicornis)): 3: Allegany, Knox Farm, Sunken Meadow
  • Number of Syrphid species whose larvae eat adelgids (adelgids are a small insect that can cause severe tree damage): 2 (in the genus Heringia) at Gilbert Lake, Grafton, Moreau Lake
  • Number of non-native, introduced species detected: 2. The common compost fly (Syritta pipiens), and common drone fly (Eristalis tenax)
  • Over half of the State Parks had at least one Syrphid species that lives predominantly in older forests.

Authored by Jeff Corser, Zoologist with NY Natural Heritage Program (NYNHP).

NY Natural Heritage Program is affiliated with SUNY College of Environmental Science and Forestry (SUNY ESF) and works in close partnership with NYS Parks and NYS DEC. The Empire State Native Pollinator Project is only one of many kinds of surveys and studies that the program conducts to provide guidance and tools for conservation of native biodiversity across New York State.

All photos by NYNHP for use by permission only

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