What's That Bug? does not endorse extermination

Subject:  Giant Grub
Geographic location of the bug:  Vista, CA
Date: 07/21/2018
Time: 02:50 AM EDT
Your letter to the bugman:  This big guy was spotted this afternoon making its way around and around the inside edge of a #3 pot where a small Cherimoya sapling is growing. I estimate it to be about 4″ long and nearly 3/4″ in diameter.
How you want your letter signed:  John L.

Giant Sphinx Hornworm

Dear John,
We have a general identification for you that we are certain about and a possible species identification that we would love verification on from an expert.  This is definitely a Hornworm, the caterpillar of a Sphinx Moth or Hawkmoth in the family Sphingidae, and because of the texture on the caudal horn that resembles members of the genus
Ceratomia like the Waved Sphinx Hornworm or the Four Horned Sphinx, we suspect it is a member of that genus or a related genus in the subfamily Sphinginae, but alas, we couldn’t match it to a single caterpillar on Sphingidae of the Americas California page.  Knowing a food plant is often very helpful, so we searched Sphingidae and Cherimoya and we found this unidentified individual from Peru in our archives that we now believe might be a Giant Sphinx Moth Caterpillar thanks to images and information on the Cheadle Center for Biodiversity & Ecological Restoration site from the University of California, Santa Barbara in an article entitled Search for the Giant Sphinx Moth that includes this information:  “This meeting’s species of interest was the giant sphinx moth, Cocytius antaeus, which originates from Mexico and has never been recorded in California before its first appearance in Santa Barbara in 2015. Since then, Russell has documented 48 observations, and this number will likely increase as the weather warms and citizens (like you!) keep an eye out and report moth sightings to the Museum. … The giant sphinx moth prefers tropical climes. Prior to its appearance in Santa Barbara, it had only been found regularly in South America, Mexico, Texas and Florida, with a few records in Arizona. C. antaeus is unique in that its long proboscis makes it the only pollinator of the rare ghost orchid (Dendrophylax lindenii) of Florida, Cuba, and the Bahamas. The moth has also been associated with the cherimoya tree (Annona cherimola), which produces fruits also called “custard apples” and is grown throughout Southern California. Where this tree is cultivated, it has to be hand-pollinated to bear fruit. Russell’s hypothesis is that the giant sphinx moth’s appearance in the States is directly linked to the transport and cultivation of cherimoya trees.”  If our identification is correct, the Hornworm you found might have been attempting to feed off the cherimoya in the pot, or perhaps, it was searching for good soft dirt in which to pupate.  Many Sphingidae larvae pupate underground, and many green caterpillars turn pink just prior to pupation.  Do you perhaps work in a nursery or have you recently purchased the cherimoya from a nursery that imports stock from Mexico?  Once we had a tentative ID, we went back to Sphingidae of the Americas and noticed that except for being green, the images of the Giant Sphinx Hornworms look very much like your individual, including the presence of a pink stripe along the dorsal surface.  We are going to try to contact Bill Oehlke to get his opinion on our identification. 

Hi Daniel, thanks for the quick reply. I have several Cherimoya trees, two in the ground, one of which was purchased at a local nursery more than five years ago, the other given to me by a friend about four years ago. The three potted trees I started from seed (variety unknown) three years ago. The tree in the pot where this caterpillar was found is the strongest of the potted trees and became root-stock this year for a couple of grafts from the five-year-old nursery tree, which has never done well and is in failing health, but produced one fruit that was delicious.
It is a mystery to me how this guy got into the pot in the first place. There are only two leaves on this tree that look to have been chewed, on their edges no less, and they are both more than four inches outside the radius of the pot. Furthermore, there is only a California Pepper tree above the pot.
Daniel/Bostjan, I will try to watch pupation. Right after I initially posted I mixed up a few cups of my compost and recycling yard compost (50-50), put it in a plastic jar and dropped the caterpillar into the 2-inch deep mix. Within an hour it disappeared under the surface. I spritz with water occasionally to moisten the soil surface. After receiving your message this morning I cleared away enough of the soil mix just to see if the big guy was still alive – yep. I left the soil mix and caterpillar as you can see in the pic (better camera). If you think I should transfer the caterpillar and the soil mix into the Cheimoya pot where I found it, I will do that. Please advise and I will do my best.
As I was about to send this message I went to take a look and since the big guy was moving I shot some video. If you are interested go here: https://drive.google.com/open?id=1MfIU8Lu4t2GS45dQc-BuslsZZK9KIlxG.


Giant Sphinx Pupating

Hi John,
Thanks for sending your video of a Giant Sphinx pupating.  We have included a still from the video in the posting.  It sounds like you are treating this Sphinx caterpillar appropriately.  We would love images of the pupa and adult if you are able to provide them.

Update:  August 26, 2018
Hi Guys,
Here are links to pics:
Pupa – https://drive.google.com/open?id=1VmfiZ8OfdILBMZ_Q58jIGLGyeEUprQ8R

Adult – https://drive.google.com/open?id=1TortVzZlmgrWmashwSYC7tzV2nUV2sEl

Specimen got away before I could get a good shot of it fully developed.

Giant Sphinx: Newly formed pupa

Dear John,
Thanks so much for providing images of the metamorphosis of the Giant Sphinx,
Cocytius antaeus.  They are a wonderful addition to the image of the Hornworm you submitted last month.

Giant Sphinx

Pupated on 7-26-18 and hatched on 8-17-18 – just in case data was lost when uploaded.

Giant Sphinx

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What's That Bug? does not endorse extermination
Location: Vista, California

3 Responses to Giant Sphinx Hornworm Metamorphosis

  1. Bostjan Dvorak says:

    Yes, this is a Cocytius antaeus caterpillar on its pupating march! All the speculations and assumptions are correct. The foodplant corresponds… Amazing record, congratulations. It should be unusual to find this species’ caterpillar in such a dry climate area, but, as already commented, there may be reasons… It would be great to observe the pupation of this caterpillar; could You do that? — The caterpillar possibly needs a more humid soil, more of it, and some leaves and other dirt – to construck a crater-like, raised hollow, a kind of nest, inside of which it will calm down and shed…

    Good luck and best wishes from Berlin,

  2. Bostjan Dvorak says:

    Dear John, dear Daniel, Thank You so much for this rich information and wonderful documentation!! – For the first time I can see a pupating caterpillar of this species – in live, which is an important experience. An amazing behaviour, the video perfectly documents its movements. This is really a great site. We can discover so much about these fascinating moths here. Many Thanks! – I guess the caterpillar is now hidden and will stay in the construction to pupate… This may take two weeks, but can be finished in some days… After a month or two, You will admire the elegant, huge moth… Good luck and best wishes from Berlin, Bostjan

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