Fruit Fly: Euarestoides acutangulus

Subject: WTB?!
Location: Denver area (larva); east of Phoenix (Thrips & E. acutangulus)
December 12, 2016 10:37 pm
I’m trying to positively identify three insects so their Genus species can be part of the file name which will have the Genus species of the flowering plant, too. (You’ll see.)
I’ll include all three images and note that I’m pretty sure I’ve tracked down the fruit fly name, Euarestoides acutangulus, though if you think otherwise, I’m all ears. Or, at least, eyes.
The (I think sawfly) larva is on a pincushion cactus blossom and might be two inches long? This is mid-May along the southern edge of the Denver area (Highland Ranch).
The Thrips is on a Mexican gold poppy, while the fruit fly is on a desert chicory. Both were shot in mid-March, east of Phoenix at about 2,100 feet elevation.
I appreciate your even taking the time to consider these.
Signature: Mark Bennett

Fruit Fly
Fruit Fly

Dear Mark,
We are more than happy to attempt your identifications, but we do have several requests.  First, please confine any future submissions to a single species, with the only exceptions being closely related species observed at the same time, like two swallowtail butterflies visiting the same blossoms, or if there is a predator/prey relationship documented.  Multiple species not all observed at the same time or place does create problems for us in the archive process.  Also please include higher resolution images that are not cropped too tightly.  We are currently attempting to standardize the images on our site to 800 pixels wide by 550 pixels high at 72 dpi.  All your submitted images are considerably smaller and they are odd shaped crops.  We agree that your Fruit Fly is
Euarestoides acutangulus based on the wing patterns evident in several BugGuide images, but BugGuide has no information on the species, which is reported in Arizona.  It is also pictured on iNaturalist.  According to ResearchGate:  “Information on the life cycle of Euarestoides acutangulus (Thomson), including observations on feeding and reproductive behavior, is presented. The fly is bivoltine in central coastal California, with overwintering occurring as diapausing pupae. Eggs were laid in the staminate florets of the host plant, Ambrosia chamissonis (Lessing) Greene (Compositae), and hatched in 4 days. Larvae fed upon the anthers of unopened florets. The amount of damage caused to a staminate head depended upon the number of larvae reaching maturity and the number of florets within the head. Larvae generally completed development in 23 days. Pupation occurred among the destroyed florets. The pupal period of non-diapausing pupae required 12 days.”  The host plant, according to CalFlora, is ” a dicot, is a perennial herb that is native to California and is also found outside of California, but is confined to western North America.” 

Hello Daniel,
Here are the three images in their uncropped state. Note, these uncropped images are artwork to me, not science. As such, they are entered in competition at a gallery and could, with luck and the favor of the judges, be selected for display. And, with more luck and perseverance, become salable prints. THUS, please observe my copyright restrictions — you may use the images on your web site and archive, for educational purposes, but they can not be reproduced or shared or in any method used for commercial purposes by you, What’s That Bug?, or any other entity without my express permission. If these terms are acceptable, and accepted, then we’re good. If not, then please delete the attached file(s).
Thanks. I do hope these help the organization.
Mark Bennett Photography

Rafinesequia neomexicana blossom Euarestoides acutangulus fruit fly desert-chicory 20130316 10cc
Rafinesequia neomexicana blossom
Euarestoides acutangulus fruit fly
desert-chicory 20130316 10cc

Dear Mark,
Thanks for providing the higher resolution files.  Just so you know, the maximum size file we post is 800 pixels by 550 pixels at 72 dpi, so they will not be suitable for reproduction purposes should anyone download images from our site.  We do respect your wishes.  We occasionally allow images from our site to be used for non-profit, educational purposes, but we always request that the person requesting the use place a comment on the posting.  Since we are including a link to your site with the posting, people can contact you directly.  We will be cropping your high resolution images and moving your copyright information so it is embedded in the image.  Thanks again.

Leave a Comment