Currently viewing the category: "blow flies"

Subject: Help! Totally stumped with this insect!
Location: Newfoundland, Canada
September 16, 2013 5:37 pm
Hi there! I’m writing from Newfoundland, Canada. Today, sept 16, 2013 I came across an insect I have never seen before. I’m usually good with bugs – but this one has me stumped!
While walking through an alder bed with goldenrod I first observed the insect flying around and then landing on goldenrod. It looked a d behaved wasp like, pumping up and down. I never seen anything like it. Then I found a group of them ! They were attracted to a group of flies that had landed on something small and deceased. The flies were landing and walking on the carcass and the insects in question were skulking around – and then I watched one sneak up and grab a fly! Then I realized they were all doing this.
I had considered Robber Fly – but the antenna look totally wrong, so does everything else! But the behaviour is very similar! It’s predatory. I’d estimate the insect to be almost an inch in length.
Sorry for the long letter but I hope the details will help! Thank you so very much!!!
Signature: Jenny in Newfoundland

Brown and Gold Rove Beetle eats Blow Fly

Gold and Brown Rove Beetle eats Blow Fly

Dear Jenny,
This is one of the most exciting letters we have received in a very long time, and we are featuring it because of your thrilling personal observations and the gorgeous photos you have taken as proof of your observations.  In our untrained minds, you have made a significant scientific observation.  This is a Gold and Brown Rove Beetle,
Ontholestes cingulatus, and it appears to be preying on a Blow Fly.  According to BugGuide, the Gold and Brown Rove Beetle can be identified because it is “Large for a rove beetle. Dark brown and hairy. Clumps of hair forms dark spots on much of body. Yellow hair forms “belt” under thorax, covers parts of last abdominal segments. Head wider than pronotum. Eyes large, prominently placed on sides of head. Found on carrion and fungi. Often turns yellow tip of abdomen upward when walking.”  BugGuide also states its habitat is:  “on carrion wherever found” and “Eggs are laid near carrion or fungi,” but this is a rare BugGuide Information Page that does not discuss what the adult Gold and Brown Rove Beetle eats.  The large eyes are mentioned, and large eyes placed on the sides of the head would make a good hunter.  We suspect that the reason the Gold and Brown Rove Beetles are attracted to the Carrion is to prey upon flies as well as to lay eggs.  The developing Fly Maggots would compete with the larval Gold and Brown Rove Beetles’ food source, so eating the flies before they can breed on the carrion probably helps more Rove Beetles to survive to the adult stage.  Thanks again for your exciting submission.  We are going to feature it on our scrolling header as well.

Brown and Gold Rove Beetle preys upon Blow Fly

Gold and Brown Rove Beetle preys upon Blow Fly

Oh that’s so fascinating! Thank you for getting back to me so quickly!
It was just the most incredible thing watching those beetles hunt the flies. It took me by surprise at first! So I grabbed my camera and decided to photograph them grabbing and eating the flies. They moved so swiftly. They actually snuck up on the fly and then just grabbed them! There were about 7 of them around the carcass, and each one had a fly in it’s legs! So interesting! Especially since I never seen one before! I could have watched them for hours. Thank you so much for identifying this insect for me! I couldn’t figure out what it was and was going crazy! I’m so happy!
Many thanks!


Subject: Creepy Fly Eating Bug??
Location: Backyard of home in Antelope Valley, CA
July 14, 2013 6:05 pm
This is the second day I have seen this bug and finally got a good picture! I live in the High Desert of Antelope Valley, CA. and have never seen it before. Did not realize it was eating a fly until I loaded the picture and wow…..CREEPY!
Signature: CheckingOutBugs

Robber Fly feeds upon Blow Fly

Robber Fly feeds upon Blow Fly

Dear CheckingOutBugs,
The predator is some species of Robber Fly and the appears to be a Blow Fly.

Subject: Fly with Really Large Eyes
Location: Northeast Florida
June 24, 2012 7:23 pm
Here’s another fly I saw the other day in my yard in northeast Florida. It wasn’t very big, about 10mm, but it had enormous eyes that almost took up its entire head. With its huge red eyes and bright blue-green body I thought it was colorful and interesting. I went looking for it on BugGuide and found that it’s a Chrysomya megacephala, also known as a Hairy Maggot Blowfly–not a very appealing name! I couldn’t find any flies like this one on What’s That Bug so I’m sending you a photo.
Signature: Karen in FL

Hairy Maggot Blow Fly

Hi Karen,
This is the second time this week you have provided us with a wonderful new fly species photo for our site as well as doing the necessary research to determine the species.  BugGuide does not provide any information on the species page for
Chrysomya megacephala, but if our knowledge of ancient languages is not too rusty, we believe megacephala refers to the large head in Greek and supports that.  On the genus page on BugGuide, we learned that “Adults are robust flies metallic green in color with a distinct blue hue when viewed under bright sunlit conditions. The posterior margin of the abdominal tergites are a brilliant blue” and as an introduced species, “It is now established in Southern California, Arizona, Texas, Louisiana, and Florida. It is also found throughout Central America, Japan, India, and the remainder of the old world.”  Backing off to the family page on BugGuide for Blow Flies, the reader learns that they are “scavengers (larvae in carrion, excrement, etc.) or parasites” and that they are “very common in a wide variety of habitats, including heavily urbanized areas.”  Normally we do not link to Wikipedia, but that resource does have an extensive page on this species where it is called the even less appealing Oriental Latrine Fly.  Wikipedia also states:  “C. megacephala is considered one of the most important species of flies to forensic science. This is because it is one of the first species to show up on a corpse.”  

Hi Daniel,
I’m glad the fly photos are helpful! I learned about BugGuide from you and What’s That Bug?, and now I always try to identify the bugs I photograph by looking here and at BugGuide. Usually I can figure it out to my satisfaction. This was such a colorful fly and turned out to have such an unpleasant name! I’ve been seeing some very pretty Long-Legged Flies and I’ll try to send you some photos of those.

Monster Beetle
Location: Western Pennsylvania
July 25, 2011 1:32 pm
I found this poor drownd beetle floatig in my swimming pool yesterday and I really want to know what it is because I have never seen anything like it before. It is huge, as you can see compared to the size of the fly. I have tried searching the internet, but couldnt find very much. Please note that I did not kill this bug. I was, in fact, trying to save its little life but it was dead when I found it.
Sorry 🙁
Signature: LadyStardust

Male Broad Necked Root Borer

Dear LadyStardust,
We cannot get the picture out of our minds of you attempting CPR on this unfortunate male Broad Necked Root Borer, our Bug of the Month for July.  The antennae of the male are much more developed than those of the female.  The backyard swimming pool is one of the most deadly traps for insects and other arthropods, and you need not fear this posting getting tagged as Unnecessary Carnage.  We understand that it was accidental drowning.  It appears as though the Fly might be a Blow Fly in the genus
Lucilia, which included the Green Bottle Fly (see BugGuide).  Blow Flies are Stage One Colonizers of decomposing corpses in the increasingly popular field of forensic entomology thanks to all of the CSI style television shows (though Crossing Jordan may have set the stage for the field with “Bug” Ravi Kapoor) and high profile murder trials like that of Casey Anthony.

Fashionable fly
Location: Northeastern Louisiana
July 23, 2011 5:34 pm
Dear Bugman,
I found this cute fly in my pool skimmer in the summer of 2010. It was so cute. It’s hairy and is black with beautiful turquoise stripes on the tail section. This is the only image I have. I tried to find out what kind of fly it was searching and searching photo files, but never found it. Hope you can help.
Signature: BugBunny

Hairy Maggot Blow Fly, maybe

Hi again BugBunny,
Generally, Flies with this type of hair pattern are Tachinid Flies, and we began our search there, but we were quickly sidetracked to the Hairy Maggot Blow Fly,
Chrysomya rufifacies, on BugGuide.  We wish your photo included a view of the head as that might provided a more conclusive identification.  While we believe the identification is correct, we cannot be certain.

Large Black Flies
March 26, 2010
For the second time in about five years, we have large black flies in our house. They are not coming in from the outside and they seem to spend most of their time on our windows. In two days, I have swatted at least 50-60, so you can imagine how gross this problem is. We do have cracks where the windows meet walls-our house is on a slab, but it shifts considerably. We have not noticed any foul odors, except under the kitchen sink, but there is not a leak or sign of anything that may have died under there. We do keep rat poison in the attic, but my husband checked and found no sign of anything that died up there. I’m concerned about the health risk and have no idea, other than swatting, how to get rid of them or where they come from. Please, I hope you can help. I’d li ke to know if they bite, spread disease and how long they live, besides how to get rid of them. (I saw Amityville Horror and already told my husband that if the walls begin to bleed, I’m outta here! LOL!)Thanks-Linda
Linda Mendez
Houston Texas

Cluster Flies

Hi Linda,
It is difficult to make out any details in your images, but your description is consistent with an outbreak of Blow Flies.  Many of the Blow Flies pictured on BugGuide have metallic coloration in shades of green and blue, but others are black like your specimens.  It is possible that the poison dispatched a rat and a female Blow Fly was attracted to the rotting flesh where she laid her eggs.  We will check with Eric Eaton to see if he concurs.  If blood begins to seep from the walls, please let us know.

Cluster Fly

Eric Eaton Agrees
Yes, I would bet on blow flies, probably “cluster flies” in the genus Pollenia.  Cluster flies are well known for harboring between walls during the colder months, then emerging in vast numbers as described in the letter.  Still, I’d have to examine actual specimens before I could be certain.

Wow, thanks so much for the speedy reply-I’ll go to your website for answers on health and getting rid of them. Some of these do have the coloration you mentioned. I appreciate your help-Linda