Currently viewing the category: "Inchworms"
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Location: Fairfield, California
March 28, 2011 7:09 pm
Every spring and summer I find these in our garden and would love to know what type of insect it is. Most recent find was on 3-26-11 on a Japanese maple, but I have found them on Lantana and also just hanging out on on the fence. I never see any feeding damage on the plants the looper is on. Thanks!
Signature: Sharon


Dear Sharon,
At the moment, we are only going to be able to provide you with a very general Family identification, which you may already know.  This is an Inchworm or Spanworm or Measuringworm in the family Geometridae, and browsing through BugGuide will reveal many similar looking caterpillars.  Inchworms are also sometimes called Loopers, though not all Loopers are in the family Geometridae.  The Inchworm gets its common name because of its manner of locomotion, which your photo beautifully illustrates.  Most caterpillars have five pairs of prolegs, but Inchworms have only two pairs, which results in the caterpillar walking forward with the fore part of the body in a typical manner, and then looping the rear portion of the body to catch up, causing the larva to appear as though it is measuring distance as it moves.  Your second photo demonstrates the marvelous camouflage ability these caterpillars have for mimicking small twigs.  We are not certain what species of Inchworm you have submitted, but we suspect the species found on the Lantana might be different from the individual you found on the maple.  Many Inchworms look very similar and they are difficult to distinguish from other members of the family.  Since it is the end of March, it is time for us to select a Bug of the Month for April, and we love your photos so much, we have decided to give your Inchworm that honor.  With the dormant trees beginning to produce tender leaves in many parts of the country, young caterpillars will start appearing as well to feed on those leaves.  The vast majority of our caterpillar submissions occur in the fall when large fully developed Caterpillars leave their host plants to find places to pupate, but sharp eyed observers will be able to find Caterpillars in the spring as well.

Inchworm camouflaged as twig

Hi Daniel!
I am absolutely thrilled (can’t stop smiling) that you have chosen my submission as worthy for BOM! I am a “wannabe” entomologist, to the point that I lead the introduction to entomology for my county’s Master Gardener training class. I am a certified Master Gardener and photography is another of my hobbies. I hope to culture this inchworm through to its adult stage (to help in the identification). I have tried before, but my captive conditions do not seem suitable for success. Perhaps a larger terrarium with native soil will help.
And thank you for the lesson on inchworm definition (vs. caterpillar), I will share this information with my Master Gardener peers and trainees! Thank you, again!
Sharon Leos

What's That Bug? does not endorse extermination

Very abundant inch worm in Kasane, Botswana
Location: Kasane, Botswana
January 14, 2011 4:58 pm
I have seen this inch worm several times around my home in Kasane, Botswana. Right now it is the rainy season and is the only time I have seen this worm. It is very colorful and has almost feather like spikes. I did handle it and it was not poisonous. Do you know what this bug is or what it will become. It is very beautiful.
Signature: Laura Marchitto Massie

Unknown Caterpillar

Dear Laura,
We are not entirely convinced that this is an Inchworm, a name along with Spanworm given to the caterpillars of moths in the family Geometridae because of the way that they crawl.  According to Bugguide:  “larvae generally have only two pairs of prolegs (at the hind end) rather than the usual five pairs in most lepidoptera; the lack of prolegs in the middle of the body necessitates the peculiar method of locomtion, drawing the hind end up to the thoracic legs to form a loop, and then extending the body forward.
”  The caterpillar in your photo has three pairs of prolegs, which is fewer than the five possessed by most caterpillars, hence its method of locomotion.  BugGuide only indicates that “larvae generally have only two pairs of prolegs” which might mean that some individuals have three pairs.  Your caterpillar also reminds us of that of the North American Funerary Dagger Moth which is depicted on BugGuide.  We will attempt to get you a species identification, and until we determine otherwise, we will archive your letter with the Inchworms.  Perhaps we can enlist assistance from our readership towards a conclusive identification of this interesting caterpillar.

Unknown Caterpillar

What's That Bug? does not endorse extermination

the hungry catapllers
Location:  satellite beach, fl
August 8, 2010 8:42 am
i found these hungry catapillers. eating away at what left of bushes in my front yard. All I know they black and green with legs in front and back.

Snowbush Spanworms

Hi Neal,
Though we were not familiar with this caterpillar, we quickly identified them as Snowbush Spanworms,
Melanchroia chephise, the caterpillar of the White-Tipped Black, because the caterpillars appeared to have but two sets of prolegs at the hind end, indicating the family Geometridae.  BugGuide provides this information:  “larvae feed on plants in the spurge family (Euphorbiaceae) such as Breynia and Phyllanthus species.”  We are having a difficult time believing these caterpillars have defoliated your shrubs as depicted in your photographs.  We suspect a rampant chain saw was the real culprit.

Snowbush Spanworm

What's That Bug? does not endorse extermination

May 2, 2010
My niece found these in her garden and I would like to know what kind of caterpillars they are and if they are harmful.
Miami, Florida

Handfull of (possibly) Azalea Caterpillars

Hi Amy,
These look like they might be Azalea Caterpillars, Datana major, but it is impossible to tell from this photo which obscures many details.  It would also be helpful to know what plant they were found eating upon.  According to BugGuide, “larvae present July to October
” and “larvae feed mainly on leaves of azalea (Rhododendron spp.) but have also been recorded on apple, blueberry, Red Oak, and Bog Rosemary (Andromeda polifoloa).”  Would it be possible to get a more detailed image and/or information on the plant they were eating?

Correction:  March 18, 2012
Snowbush Spanworms
Thanks to a comment we just received from Nikki that correctly identified these as Snowbush Spanworms, we are able to link to the BugGuide information page on the species that states:  “larvae feed on plants in the spurge family (Euphorbiaceae) such as Breynia and Phyllanthus species.”

What's That Bug? does not endorse extermination

Horned Spanworm
April 18, 2010
Thanks for all the help you’ve given me! But here’s one I found myself that I’d like to share: a horned spanworm (OK, I’m pretty sure that’s what it is). I found it lurking on a maple seedling, and from what I’ve read, was probably responsible for the chew marks on several of the maple leaves (primary habitat is deciduous and coniferous trees). It is interesting to note that between the first picture and the latter pictures, the ‘tentacles’ continued extending (must be camera shy). I found the textured orange patch on his upper back very interesting; I saw it on few of the other photos I viewed. Also, it was very reluctant to uncurl.
Karen H.
Belleview, FL

Horned Spanworm

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What's That Bug? does not endorse extermination

Very, very tiny black caterpillar with white spots
February 8, 2010
‘Ello Bugman!
Today I found a very, very tiny black caterpillar. He’s approx 3mm long and has tiny white spots which first I thought were stripes across his body.
I live in Australia in NSW and it is currently Summer (although has been wet and rainy for a week now).
I don’t know what the plant is. It self-seeded from somewhere and I don’t mind if he eats it all up.
It would be interesting however, to find out what he is, how big he will get and what he is to become.
Penrith (Western Sydney, NSW Australia)

unknown Inchworm from Australia

Hi Bronwyn,
We can say for certain that this is a Spanworm or Inchworm caterpillar in the family Geometridae, but we would need additional time to determine the species.  Since it is so small, it is an early instar, and it may undergo five additional molts before pupating.  Each molt or instar may have different markings and coloration.  Generally, most caterpillar photos are of the final instar, and it can be quite difficult to properly identify the earlier instars.  Knowing the food plant often helps, but alas, we do not recognize your plant.  As the caterpillar grows, molts and changes, you may send additional images in the hope that would assist in identification.

Host Plant

What's That Bug? does not endorse extermination