Subject: Unknown fling ?
Location: Winona area of Arkansas
June 8, 2015 8:03 am
We came across this feeding on butterfly weed and cannot identify. Can you help us.
Signature: Lon and Annie
Dear Lon and Annie,
This is a very exciting posting for us. Though it appears green, this is is known as a Purple Small Headed Fly, Lasia purpurata, and it is only the third submission we have received of this species since we went online in the late 1990s, and the last submission was nine years ago. All three submissions of Purple Small Headed Flies are nectaring on the same blossoms and all are from Arkansas. Of the 2006 sighting by Julie Lansdale, Dr. Jeffrey K. Barnes, Curator of The Arthropod Museum in the Department of Entomology of the University of Arkansas in Fayetteville wrote: “What an exciting find! This is Lasia purpurata, a fly in the family Acroceridae. The larvae of this species are parasites of tarantulas. Adults, as you have observed, are nectar feeders. This is not a commonly observed insect.” There is also an image posted to the University of Arkansas website where it states: “In 1933, Harvard University entomologist Joseph Bequaert described Lasia purpurata from a large, pilose, metallic blue fly with strong purple reflections that was collected in Oklahoma. Adults are often found feeding on nectar with their long proboscides inserted in flowers of butterfly weed, Asclepias tuberosa. This species is now known to occur also in Arkansas and Texas. While little is known of the biology of this particular species, we do have some understanding of general family biology. Larvae of all biologically known species are internal parasitoids of spiders. Large numbers of eggs are deposited in the vicinity of host spiders. Most species have planidium-like first instar larvae, that is to say they are strongly sclerotized and have spine-like locomotory processes. These young larvae are capable of crawling and jumping in search of spider hosts. Upon finding hosts they burrow though the integument and migrate to the spiders’ book lungs, where they can breathe outside air as they remain in diapause for several months to several years. Larvae of the subfamily Panopinae, to which Lasia belongs, have long second stadia and 4-5 day third stadia. In 1958, William Baerg, retired head of the Department of Entomology at the University of Arkansas and world renowned tarantula expert, reported that acrocerid flies, probably Lasia purpurata, sometimes attack Arkansas tarantulas. Female tarantulas produced 4-6 of these dipterous parasites. The parasites emerged from the tarantulas’ book lungs as larvae, and the tarantulas soon died. At Pea Ridge, most tarantulas appeared to be infested. The parasites emerged from mid April to mid May.”
Thank you for this information. we were stumped. My Granddaughter, Annie, age 12, and I, age 74, are very excited that this is only the third submission you have received for the Purple Small Headed Fly. Please keep up the good work that you do. This is the best use of the social media we are surrounded with today.
God bless you.
That is very kind of you to say Lon. Back in the late 1990s when we were approached to write a column for the now defunct American Homebody, we defended our decision to write a column on insect identification because we maintained that “Everybody wants to know ‘What’s That Bug?'” but we never dreamed how accurate that statement would actually prove to be. We really do have a strong network of regular readers and contributors. We are very envious at your sighting of the Purple Small Headed Fly because they are apparently quite rare.