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Do Spiders regrow Legs? & what are these flies?
June 5, 2010
Recently had a small lynx spider on a plant in my yard (spring) missing several legs, I also noticed a golden spider missing legs in a web in winter last year. I’m curious do spiders regrow limbs lost? And also the same golden spider species seems to have flies on it or on its prey in the web, I have never seen this before and the flies seem to not care they were on a spider, and in its web..
Any idea what the flies are doing and what kind of flies they are..
Thanks, Dee
Polk County, Florida, USA

Freeloader Flies share meal with Golden Silk Spider

Hi Again Dee,
The flies with your Golden Silk Spider are Freeloader Flies in the family Milichiidae.  According to Dr. Irina Brake  who coined the English name Freeloader Flies
on her Milichiidae online website, some members of the family “are kleptoparasitic, feeding on the prey of spiders or predaceous insects.“  On the Biology of Milichiidae page, Dr. Brake indicates:  “Another very interesting feature of Milichiidae behavior is kleptoparasitism or commensalism. Species of several genera suck at the prey of spiders or predatory insects such as Reduviidae, Asilidae, Mantidae, or Odonata. Mostly they are attracted to predators feeding on stink bugs (Pentatomidae) or squash bugs (Coreidae) (Frost 1913, Robinson & Robinson 1977, Sivinski & Stowe 1980, Landau & Gaylor 1987). In almost all cases it is only the females that are kleptoparasitic. In some cases a close association between milichiid and predator has been postulated, because it was observed that the fly “rides” on the predator for some time, staying with the one predator rather than changing between different predators (Biró 1899, Robinson & Robinson 1977).“  Regarding the leg regeneration question, we have seen images of a Fishing Spider with several smaller legs, and the hypothesis is that if a spider loses its legs while very young, stunted legs may regenerate.  Alas, older spiders will not regenerate their legs.

Golden Silk Spider: double amputee

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aussietrev foodchain
February 19, 2010
Hi guys,
Thanks for clearing up that velvet ant gender. This Lynx spider has caught herself a pod boring bug but is having to share it with minute flies that feed on the victims of spiders. I guess they must be immune to the effects of venom or feed before it has made its way through the body of the bug.
aussietrev
Queensland. Australia

Common Lynx Spider and Freeloader Flies eat Pod Sucking Bug

Hi Trevor,
This is such an intricate Food Chain image and we are impressed with the excellent focus and detail on the individuals.  The Common Lynx Spider is well represented on the Brisbane Insect website, but the prey you have indicated, the Pod Sucking Bug, is not recognizable in your photo.  We did locate images of the Pod Sucking Bug, Riptortus serripes, on the Brisbane Insect website.  You sent us another example of Kleptoparasitism with Freeloader Flies last year, and we did extensive research at that time on the phenomenon.  These Freeloader Flies are in the family Milichiidae, and the Biology of Milichiidae page has this information:  “Another very interesting feature of Milichiidae behavior is kleptoparasitism or commensalism. Species of several genera suck at the prey of spiders or predatory insects such as Reduviidae, Asilidae, Mantidae, or Odonata. Mostly they are attracted to predators feeding on stink bugs (Pentatomidae) or squash bugs (Coreidae) (Frost 1913, Robinson & Robinson 1977, Sivinski & Stowe 1980, Landau & Gaylor 1987). In almost all cases it is only the females that are kleptoparasitic. In some cases a close association between milichiid and predator has been postulated, because it was observed that the fly “rides” on the predator for some time, staying with the one predator rather than changing between different predators (Biró 1899, Robinson & Robinson 1977).
“  Irina Brake is the expert on this fascinating family.
Interestingly, in the past two days, we have received numerous beetle corrections from a Dr. Trevor J Hawkeswood of Australia, and we lamented that we have not had any recent submissions from you.

Common Lynx Spider and Freeloader Flies feed on Pod Sucking Bug in Australia

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Kleptoparasitic flies
Thu, Mar 19, 2009 at 2:37 AM
Hi guys,
I got this photo of tiny flies trying to get to the ant captured by this jumping spider. Apparently they are Milichiidae (Diptera, Schizophora) some of which are kleptoparasitic of spiders, some specialising in ant snacks such as this one. The spider is a female Salticid, Zenodorus orbiculatus known locally as ant hunters. She is about 7mm long so you can see how tiny those flies are.
aussietrev
Queensland, Australia

Freeloader Flies share Ant Hunter's prey

Freeloader Flies share Ant Hunter's prey

Hi Trevor,
Though you have a long history of providing our site with awesome images of Australian fauna, this image is, in our opinion, one of the most fascinating. The fact that you captured this nuanced example of Kleptoparasitism is phenomenal. One animal stealing food or prey from another is common in the animal kingdom, and it is easily observed in our own brand new aquarium, but to photograph these minuscule creatures evolutionarily adapted to this activity is nothing short of fantastic. These Freeloader Flies, as they are called on one website, in the family Milichiidae, are described by Irina Brake on the Introduction to Milichiidae website: “Thu, 2009-02-12 13:48 — Irina Brake
The Milichiidae (Diptera, Schizophora) are small, mostly black acalyptrate flies. The family contains about 240 described species in 19 genera and is worldwide in distribution.
The behavior of several species of Milichiidae is very specialized. For example, in some species the adults are myrmecophilous (= ant-loving), whilst in some others they are kleptoparasitic, feeding on the prey of spiders or predaceous insects.
The habitats of Milichiidae are diverse. Adults can be collected in open landscapes, such as steppes or meadows, in wadis, at the edges of forests, inside forests, in the forest canopy, in stables or houses, or even in caves. However, they do not seem to be attracted to coastal habitats or to other places near water.
The Milichiidae are divided into three subfamilies, Madizinae, Milichiinae, and Phyllomyzinae.
Common names
Common names are only rarely cited for Milichiidae and seem to be more of an invention of the author than a commonly used name. The English term “filth flies”, for example, which is sometimes used for Milichiidae, was introduced by Sabrosky (1959) in the title of a paper about the genus Meoneura , which now belongs to the family Carnidae. Sabrosky probably used the general expression “filth fly” to describe the biology rather than intending the term to be a common name for the family Milichiidae. The term “filth flies” is generally used for several different taxa associated with ‘filth’.
Since people keep stumbling over the name ‘Milichiidae, I herewith introduce a new english common name: “freeloader flies”. The name refers to the biology of Milichiidae. Definitions for ‘freeloader’ are: ‘ someone who takes advantage of the generosity of others’ ( wordnet.princeton.edu/perl/webwn ) or ‘ one who depends on another for support without reciprocating’ ( http://www.answers.com ). ”
BugGuide also has information on the family Milichiidae. The Geocities website has some nice images of the Ant Eater Spider or Ant Hunter Spider, Zenodorus orbiculatus.

Correction: Mon Mar 23, 2009  7:08:13 AM America/Los_Angeles
Dear Daniel,
thanks for alerting me to your photo and citing my webpage. However, I
discussed it with a collegue of mine and we both think that your flies
are Chloropidae, not Milichiidae. Michael von Tschirnhaus is a
Chloropidae specialist and has more experience with actually watching
the live flies than I have. He wrote to me that from the habitus the
flies are certainly Chloropidae. There are several species who are
kleptoparasitic on spiders. He doesn’t know all Australian genera, so he
can’t tell you which genus it is. Many species of different genera
develop in spider cocons and stay with the spider for a longer period of
time. They can wait endless in the spider net.
Best wishes,
Irina

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