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In July of 2005 I received an
email from a Biologist at the Balcones Canyonland's NWR in Texas. A local
gardener had some 'giant flies' emerging on her property. She described them
as being 'fairly common' as they emerged from her compost heap. She apparently even
had the pupal cases of some of them. She turned some over to the biologist,
Chuck Sexton, who proceeded to key them to
Mallophora after recognizing
that they weren't just any flies, they were robber flies. This is no small
feat, keying in the big eastern genera key without some fly experience. Maybe
he had some. But this is indeed
Mallophora
leschenaulti, one of the largest
Asilids
in the US. This is a scan and not a photo but I brightened it up for improved
viewing (thanks to
Gayle Strickland
for further photoshop enhancements).
Interestingly, here is what
Bromley had to say in his Robber Flies of Texas paper from 1934 about what was
then known as
Mallophora belzebul:
This huge species is represented
in Texas in the U. S. National Museum by
three specimens: Uvalde, 1917, (D. C. Parman); Concan, 1910, (F. C. Pratt);
and Sonora, 1924, (O. G. Babcock) (J. M. Aldrich). Under date of March 26,
1927, Mr. D. C. Parman wrote me that specimens collected on July 17, 1917,
were taken by a ranchman:
"For the last week large numbers of the flies have
been emerging in a goat pen. They have never been seen except early in the
mornings and have never been observed to fly (supposedly they have just
emerged as there were several pupae cases in the lot brought in). The
ranchman stated that ground was covered in the goat pens as large as a room
15x20 ft. He is an old settler here and he and his neighbors have never seen
the fly before...The
specimens were all taken near Montel. It was
interesting in that several other species commonly found in Mexico and S.
America were found here in 1917. It was thought that they were brought in by
a tropical storm in August, 1916." The specimens were identified by Mr.
Frederick Knab at the National museum. Chisos Mts., Brewster Co., July 19
(Duncan) (F. R. Cole).
And from
Nancy Radding, a master
naturalist in the Austin area this info:
she actually lives in the south
part
of Austin, Texas, in a residential neighborhood in town. She said these
flies are common in a large compost pile in her yard. The compost is
primarily made up of leaves of pecan trees with a small proportion of
household vegetable scraps. The leaf pile is usually about 8 ft x 12 ft
and, in the fall, starts off a few feet thick before it "cooks down" by the
following summer.
She first recalls seeing the Bee-killers emerging in 2003. She wasn't home
in the summer in 2004 to notice them. This year, the emergence started
about June 23-25 and continues to this week so far.
The emergence only
lasts a few weeks. Dozens of the flies have emerged from the compost,
sometimes 9 to 12 at a time. Most emerge in the morning hours but they may
emerge any time during the day. Typically, the pupae "wiggle" up and out
of the leaf pile and rest on top for a time, presumably drying out and
gaining thermal energy. The adult flies emerge and rest quietly by the
pupal case for awhile before flying off. At those times, they are easily
handled.
Interesting that some of
these may have been storm borne from south of the border. Impressive insects.
It is more likely that the imported pig manure or compost in the first site
was the method of import. I vote for Belzebul's Bee-eater as the common name.
And now in 2013 we have bugguide records from Houston to San Antonio to
Austin and one up just south of Dallas. It is possible that further
movement of compost could result in emergence elsewhere.
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