Published: March 31, 2021

Today’s WowBibionids(March Flies)take us back to theEocene,56to34million years ago.FossilizedBibionidslike theseare very common in fossil insect deposits from Florissant and the Green River Formation in babyֱapp. They are often found together in groups of multiple specimens in Green River deposits (sometimes more than 20together). These specimens were collected in the early 2000s from the Green River Formation by Mr. David Kohls.Green River Formationoutcropscan be foundat the intersection of babyֱapp, Wyoming and Utah. It is formed of sediments from an ancient group of intermountain lakes. A very cool feature is that seasonal sediment varied in color, so layers from single years can be studied!March Flies

Today’s Bibionids are known to swarm in clusters during the spring and the adults of the species are herbivores and pollinators.Some species areknown as “love bugs” for their conspicuous copula behavior (staying attached for long periods, even in flight),somespeciesdo not eat(too busy mating?), instead surviving on food ingestedduringtheirlarvalstage.

In the early 1900s, CU Curator TDACockerellcollected and described some of the first known bibionids from Florissant(Florissant and Green River Formation are two of the best sites in the world for Eocene fossils—both right here in babyֱapp). You can, from 1909, for free from the Biodiversity Heritage Library if you would like to see what a scientific species description looks like from that era. They were much shorter and contained few, if any photographs, but sometimes a line drawing was included. Today we are able to include much more lengthy descriptions of morphology and lots of high-resolution digital images that clearly show theidentifyingmorphology.This technology along with the incredible preservation of some Green River Formation insect fossils,allowsidentification to family and subfamilyandsometimes show color patterns, wing venation, and sex-related characteristics.

Catalog Numbers: UCM64482,69269,82648,86476
Scientific Name:Bibionidae
Description: Fossil March Flies
Collected by D. Kohls, Green River Formation, babyֱapp
Age: Eocene
Published Papers:
Cockerell, TDA. 1909. Fossil insects from babyֱapp. The Entomologist. 42: 170-174.
Cockerell, TDA. 1914. Miocene Fossil Insects. Proceedings of the Academy of Natural SciencesPhilladelphia. 66: 634-648.

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