Monday, May 2, 2011

orange tortrix ~ 05/02/11 ~ at home


orange tortrix moth
Argyrotaenia franciscana (aka Tortrix citrana)

Late last fall, maybe October or November, I noticed my geranium had a few rolled leaf edges. I pulled one open and found silk acting like glue to keep part of the leaf curled around a tiny brown pupa. Out of curiosity to know which moth it was, I collected 3 of these leaves, stuck them in a jar with a pantyhose top, and then promptly forgot about them during the holidays.

By mid-February, we had a particularly windy storm that knocked my potted geranium plant over, which broke off a stem. I put the stem in water to root and placed it near the window behind my computer. The next morning, I found little black specks sprinkled over my desk and keyboard. I cleaned it up figuring I must have caught some of Andy's coffee grounds in my sleeve as I dumped the breakfast compost collection. Later, as I was working on the computer, a black speck landed on the desk and then another. I looked up to see if something was on the ceiling and then stood up to look behind the computer. I discovered a couple black specks stuck near a tiny hole in the geranium stem. Apparently, I had a poop-shooting, geranium-eating caterpillar. I swear the poop shot at least 18" from the windowsill to my desk and keyboard. I wonder if the caterpillar had weakened the stem enough that that was the reason why it was the only stem to break.

In any case, I promptly placed the geranium container with caterpillar outside, despite the wind. Over the next week or so, I watched the little, green caterpillar peek out every now and again from its hole, still shooting poop. That part of the stem died and fell off, exposing the brown pupa within the hollowed out stem. I placed the stem piece into the jar with the other rolled leaves, whereupon I discovered the 3 other pupae had already eclosed and died. Oops. Well, I should confess, I'm not too fussed about the death of these moths. I let this last pupa emerge and die as well. Since then, every time I find a spider wandering around, I move it to my geranium with hopes it'll find a meal or two or more. Now, if only I can figure out a non-chemical way to get rid of the mealy bugs and the ants that tend them. Geraniums must be tasty.

Shown in the 2nd pic above are the orange tortrix moth carcasses and pupal casings. They're commonly named because they like to eat orange trees, not because the adults are an orangish color. There's significant wing pattern variation within A. franciscana; however, given the different methods of pupation (leaf rolling and within a stem) that I observed, I wonder if the individual shown on the left may be A. isolatissima, the one that shot poop.

Indeed numerous Tortricidae moths (many of them leafrollers), both caterpillars and adults look similar, including the now infamous to our area of California Epiphyas postvittana (light brown apple moth, aka LBAM). Back in 2007-2008 (and probably still), there was quite the hubbub with quarantines, court injunctions, protests, and numerous claims of ill health due to "emergency" aerial spraying to "eradicate" LBAM using pheromones and undisclosed other chemical carriers in Monterey and Santa Cruz counties, as well as other counties. All this came about as a result of Jerry Powell, co-author of Moths of Western North America, chancing upon this never-before-found-here-in-the-U.S. moth in one of his usual Berkeley backyard trappings in the summer of 2006. Some university experts suggested LBAM may have been in our area for years and simply never properly identified before. Yet, it suddenly became an emergency to spray over urban areas adjacent to a national marine sanctuary with a newly untested and extremely expensive product without an EIR approval as required by law. For more information on this controversy, click to read Wikipedia, SFGate.com, and Monterey County Weekly. (It's unfortunate that older news articles are not easily accessible on the web, because I can't find the best informed sites I had bookmarked back in 2008.) I do remember 2 rounds of spraying in the fall of 2008. The planes flew back and forth over Pacific Grove and Monterey for hours in the evenings. We could smell it and our noses were a bit runny through to the next day.

Speaking of pheromones and getting back to the main topic of this post... the first picture above is the underside of one of my dead orange tortrix moths (looks just like one of those drab dead moths found in your windowsills, eh?). After close examination of the picture, I found the fluffy butt that looked like something got shot out of it to be intriguing. My first thought was hair-pencils (long, hair-like projections, aka setae, on male Lepidoptera that function in releasing pheromones), but these look like scales, just like the scales on the wings of Lepidoptera. So, I've decided the exploded butt fluff must be a scent scale patch. People who are familiar with monarch butterflies know males have scent scale patches that look like black dots on the hind wings. I hadn't considered before now that scent scales could occur in other places than wings. Learn something new every day. If anyone has more information, I'd love to hear from you.

ps - I owe much gratitude to Chris Grinter of The Skeptical Moth, an entomologist at the California Academy of Sciences, for identifying several moths for me from e-mailed photos. While I've been sick and on meds, I could easily take pictures with my point-and-shoot, but it's been a challenge staying awake at the computer long enough to look up IDs, let alone write a comprehensible blog post. So, thank you very much, Chris!

5 comments:

Allison said...

tiny bugs all lined up in a row. Amazing, but it makes me kind of sad! :)

Nature ID (Katie) said...

It is kind of sad. For me, it is interesting to know what was eating my geranium.

Kat said...

Yes I've come across this for two years running, when I bring a geranium in from outside.

Could the black specks be eggs or are they definitely poo, do you think?

Katie (Nature ID) said...

Hi, Kat. Yes, little loose black specks, like coffee grounds, are very likely caterpillar poop. I guess they could be eggs if they're attached to the leaf in some way. Send me a picture if you want to be sure.

Kat said...

Yes like black coffee grounds, but they needed to be rubbed - pouring water alone did not push them off the leaves, unless the leaves themselves were encouraging them to stick. Can't send a photo as have, hopefully, removed all of them! (And put 2 green caterpillars at the bottom of the garden!)

Last year I underestimated how damaging they'd be and lost 2 plants to them

Will be interesting to see if more appear now !

Will send a photo if I rescue more geraniums from the oncoming winter, as they'll be bound to have caterpillars too.