Moth and privet...

So, I was just flipping through my new favorite field guide, Moths of Southeastern North America by Seabrooke Leckie (@seabrookeleckie ) and David Beadle, and I stumbled upon the genus Palpita — these are really pretty moths, and I’ve only seen a few.

Well, I noticed a particularly interesting comment on the host plant for the species Palpita atrisquamalis (“Gracile Palpita”) on page 224... “HOSTS: Can be a pest on ornamental privet.” I’ve searched around a little bit, but I can’t seem to find a source for this specific species... Another species of Palpita has been documented in China as wonderful pest of Ligustrum quihoui: http://en.cnki.com.cn/Article_en/CJFDTOTAL-KCZS200501021.htm

Hmmm... I wonder if these caterpillars eat all species of privets? We have a major issue with privet in Texas as an invasive species (4 species), and I wonder if this moth can be raised on the various species we have... And, if they can be raised on our invasive privets, I wonder if they could be used as a mechanism of control (if not complete control, perhaps they can be used as assistance control).

It does beg the question: privet it amazingly abundant here, so why isn’t the moth? If there are plentiful resources, wouldn’t there be an overabundance of this species of moth? I’m not sure... Perhaps it doesn’t use the privets we have if offered other species to eat... Or, there may be so many predator pressures that keep this species in check...

So, who wants to do some experiments with me? :)

First of all, we need some adults... Now, I only seen a single one, so I’m really going to start keeping an eye open for more. Quite a few folks here on iNat have observed them. And I know that even a few folks have quite a bit of experience raising caterpillars of various species...

Here are some websites that show the adults:
http://mothphotographersgroup.msstate.edu/species.php?hodges=5220
https://bugguide.net/node/view/90182/bgimage
http://www.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=450516

If you do see one, try to collect it alive, put it in a container with some meshing (for air) and toss in some privet with it. If you’re able to get various species of privet, cool. If you can just find one species of privet, try just that one. See if the adult (well, only females, although I’m not sure how to tell the sexes apart) lays her eggs on the privet. You don’t have to raise the caterpillars unless you want to — if you’re able to hold on to the eggs, I can perhaps come by and pick them up...

If nothing else, we can at least add a caterpillar image onto bugguide for this specific species! :) Maybe we can try this with the other species of Palpita too…

I’m just kinda thinking out loud on this journal post. Please chime in with some other ideas and suggestions — and let me know if you want to experiment with this! :) This is an iNat-driven project, so let’s do it together (again, only if you want to!).

Posted by sambiology sambiology, May 21, 2018 16:02

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I'll keep my eye out. I looked up the one I found and seems I found it at my house. Umm, don't shoot me, I didn't put it in, but I do have a privet in my front yard. You'd think I'd see these moths more often. Maybe they don't like my type of privet.

Posted by tfandre about 2 years ago (Flag)
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Funny enough, I saw a Gracile Palpita in Del Rio (one of my favorite moths from the trip!). I've seen that one and two other species at my house. Seems the blacklight gets them pretty easily. I'm sure there's privet somewhere in my neighborhood. I had one start to pop up in my back yard that I cut down, but if it's like any of the other invasives in my yard, it's probably sending some shoots up.

A challenge! I like! We'll see if I can get lucky :D

The HOSTS database lists a couple other host plants, but it really does look like Privet is its favorite. http://www.nhm.ac.uk/our-science/data/hostplants/search/list.dsml?searchPageURL=index.dsml&Familyqtype=starts+with&Family=&PFamilyqtype=starts+with&PFamily=&Genusqtype=starts+with&Genus=palpita&PGenusqtype=starts+with&PGenus=&Speciesqtype=starts+with&Species=&PSpeciesqtype=starts+with&PSpecies=&Country=USA&sort=Family

Posted by nanofishology about 2 years ago (Flag)
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I'll definitely keep a lookout! I wouldn't mind raising some if I find them. I just need some tips on keeping them alive... :)

Posted by wildcarrot about 2 years ago (Flag)
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I see Gracile Palpita at my home porchlight and privet's are certain common in the area; a big "Wax-leaf Ligustrum" is just across the fence in my neighbors yard. But your right that the abundance of this species doesn't seem to match the abundance of that invasive set of plants. Otherwise the species would be one of the most common at my porchlight, which it is not. I see Four-spotted Palpita much more frequently, and the closely related Diaphania costata is probably the most numerous of this set. (Are they all Ligustrum feeders??)

I also documented Gracile Palpita in Del Rio (to be uploaded soon) but I don't recall seeing any Ligustrm in/near our mothing locations. Surely it was present in nearby residential areas along US 90, for instance.

Posted by gcwarbler about 2 years ago (Flag)
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Palpita's are a dime a dozen here. Several different species are prolific at the porch lights, and I see them in the tall grass frequently. I have poor luck raising cats. Right now I have two large clusters of ugly nest caterpillars in terrariums and a bunch of braconid wasps are emerging instead. Thats my luck raising cats.....

Posted by royaltyler about 2 years ago (Flag)
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I will certainly keep watch and collect. I see the Four-spotted frequently and one other on one occasion. Love to learn how to rear them.

Posted by mikef451 about 2 years ago (Flag)
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So, a few years back, I was at a park in Fort Worth and noticed some lovely defoliation on privet (Ligustrum quihoui):
https://www.inaturalist.org/observations/1831452
https://www.inaturalist.org/observations/3840268

I looked for some caterpillars briefly, but I didn't spot any. In hindsight, I should have spent a lot more time looking... I'll check again this year in August.

I've never raised caterpillars before, so I have no experience. But it does sound like @nanofishology , @kimberlietx , and @royaltyler do have some experience. Here's a site on raising butterflies (which are really just day-flying moths!): http://www.raisingbutterflies.org/getting_started/

Overall, this is just a little experiment, so we'll see how it goes! :) Again, if you catch an adult, toss it in a container with some privet and see if it even lays eggs on the plant... I wonder how selective the various species are, especially if they aren't given much of a choice!

Posted by sambiology about 2 years ago (Flag)
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@sambiology, did you look for leafcutter ants around those defoliated ligustrums? We’ve seen them kill a few glossy privets, although even humongous colonies aren’t up to the task of taking out more than a handful of moderately sized ones (not quite 4 inches dbh, about 15 to 20 feet tall, and with a moderate spread to the canopy). I don’t recall seeing them on small-leafed privets, but I’m also not certain that I’ve seen any small-leafed privets near the two colonies I know of. That could mean that they have a high preference for Chinese privet, quihoui privet, or both. (Those are the only two small-leafed privets I’ve found in Austin.)

If the moths could be encouraged to remove the small-leafed privet, that would suit me just fine. They aren’t as invasive as glossy privet in my area, and with their many small trunks they are a pain to control.

Posted by baldeagle about 2 years ago (Flag)
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Just thinking out loud also, I think adult perennial plants are quite tolerant of being munched on. So I'm not sure that privets would be controlled in any meaningful way by caterpillars. I think you'd need something that ate the seeds.

Posted by pfau_tarleton about 2 years ago (Flag)
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@sambiology If a moth needs to lay eggs, she will do it on ANYTHING she can rub her butt on. In captivity, they have covered the interior of their container in eggs (I had polyphemus eggs EVERYWHERE). When I have kicked them out, and placed them on some random non-host plant, the females have gone insane laying their eggs on EVERYTHING.

Examples:
https://www.inaturalist.org/observations/7734737
https://www.inaturalist.org/observations/8993104

I have pictures of one who laid eggs ON TOP OF another clutch of a different species moth's eggs. Ridiculous.
I guess when ya gotta go, ya gotta go :)

Posted by nanofishology about 2 years ago (Flag)
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@pfau_tarleton, the abstract of the Chinese reference @sambiology cited laments that Palpita annulata can kill Ligustrum quihoui. Even if it’s only a 5 percent kill rate, so long as this moth doesn’t have any other larval hosts, I’d take it! And any plants that survive an onslaught of larvae would be weaker, so they would produce fewer seeds, right?

Posted by baldeagle about 2 years ago (Flag)
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There’s only one observation of Palpita annulata in iNaturalist, and it’s in Queensland, Australia. I think we need a grant to mount an expedition to see if we can find a breeding population there. As part of the project, we should make sure they aren’t found near the Great Barrier Reef.

You never know!

Posted by baldeagle about 2 years ago (Flag)
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is that the only species of palpita you are interested in? I've seen two other species:
Four-spotted Palpita - Hodges#5218 Palpita quadristigmalis on tropical milkweed in my yard and
White Palpita Moth Hodges#5216 (Diaphania costata) on buttonbush flowers at White Rock lake.

Posted by kalamurphyking about 2 years ago (Flag)
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I see that the article says the plants wither and die, but you can cut a privet off at ground level and it'll come right back. I've never seen caterpillars kill a perennial shrub or tree, even if the caterpillars totally defoliate the plant. Here's how hard it is to kill a privet:
http://homeguides.sfgate.com/information-kill-privet-hedge-84794.html

Posted by pfau_tarleton about 2 years ago (Flag)
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I think that this may be an interesting experiment to see if the caterpillars actually do eat our invasive privets. It may not be much of a mechanism of control, but if the plants are defoliated, perhaps it will allow the sunlight to penetrate to the ground to help out other plant species... And maybe it could be effective for seedlings... Perhaps! I think it'd be just a fun little experiment to see what happens when we try to raise caterpillars on privet... If there's any success, then we can perhaps move to some more experimentation -- how long and how many does it take to defoliate a privet, how many generations can be reared on privet, etc...

Who knows? It could just be another tool in the tool box! :)

Posted by sambiology about 2 years ago (Flag)
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I'm getting a little uneasy with the narrowness and naiveté of this discussion. If someone wants to see if some local Gracile Palpita's will eat privet, fine. But I hope no one is thinking seriously--at this stage of research--of bringing in some foreign Palpita in an attempt to get rid of privet. The historical ecology of this continent (and all others) is replete with the disasters (and a few success stories) which such efforts can bring on. For instance, what else do Gracile Palpita's feed on? Something native? What else would the foreign Palpita's forage on here? Would they exhibit host plant switching to something we don't want to see eliminated? There are big scary questions that haven't been answered.

Posted by gcwarbler about 2 years ago (Flag)
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Almost all the Palpita species in North America typically use Oleaceae family genera, and there are certainly a fair number of genera besides Ligustrum in that family in Texas. Since Palpita are native, perhaps they use Ligustrum if other host plants aren't available...in suburbs, and nurseries that churn out 1000s of Ligustrum.

In my area, near the coast, the introduction of "exotic" moths to control invasive Water Hyacinth and Alligatorweed has shown negligible results. At a plant's certain biomass there simply aren't enough moths. My take is that we'd be better off looking for borers, or insects that carry disease - like the Emerald Ash Borer, Elm Bark Beetle, or the Asian Citrus Psyllid (the latter with a 100% citrus kill rate) - or a virulent fungus like the Chestnut Blight, for control of invasive plants.

Posted by krancmm about 2 years ago (Flag)
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Chuck, I agree 100%. I think the "catch a moth and see if it will lay eggs" aspect is fun, and recognize the "maybe we can get rid of privet with them!" as more of a joke on the wishful thinking end of things. I had a giant leopard moth caterpillar consume the entirety of an invasive mulberry sapling and was rooting for him, but I know better than to think they could make an appreciable impact on the population of the stupid things.

Posted by nanofishology about 2 years ago (Flag)
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Good points, all.

I guess I'm kind of just curious as to what defoliated those privets

( https://www.inaturalist.org/observations/1831452
https://www.inaturalist.org/observations/3840268 )

I definitely am curious as to see which Oleaceae that these Palpita prefer (Forestiera, maybe?), and I'm also curious as to seeing what the caterpillars look like -- bugguide lacks a photo of the caterpillar: https://bugguide.net/node/view/90182/bgimage

As to the utility of these native moths to actually control Ligustrum, yeah, it's not too likely... I regularly just tell folks that we have to use the tool of chemistry to combat privet (nuke it!).

Just a fun little experiment to feed some curiosity.

Posted by sambiology about 2 years ago (Flag)
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Sam,
You say, "First of all, we need some adults." My driver license says I qualify, but around iNatters I feel like a kid (admittedly, a kid in a candy store). I'm up for doing what I can. That said, I have to also agree with Chuck and Alysa. One of the first things I learned about nature is be careful what you wish for.

Posted by cameralenswrangler about 2 years ago (Flag)
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I will be keeping a lookout!

Posted by bosqueaaron about 2 years ago (Flag)
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Of the gracile palpitas in iNat that were photographed on living plants, we have:

Something fuzzy, not Ligustrum: https://www.inaturalist.org/observations/10838201
Fabaceae? https://www.inaturalist.org/observations/7881959
something that's not Ligustrum: https://www.inaturalist.org/observations/5413285
mistflower: https://www.inaturalist.org/observations/4372352
Many of the photographs were taken in areas where there are few to no Ligustrums, so I think they must be eating other stuff too. But since they are already in the state, it would be great if they do happen to love Ligustrum.

Posted by alisonnorthup about 2 years ago (Flag)
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Chuck (@gcwarbler), I was thinking more along the lines of bioengineering a privet-eating Mothra to rescue us from our plight—something that would do to privet what hornworms do to tomatoes. And, yes, I am saying all of this with tongue

As you can affirm, I know very well what it takes to kill a ligustrum: remove a hand’s width of bark, phloem, and cambium, all the way down to sapwood, all the way around each trunk, and scrape down to dry-ish wood (if it turns brown before you finish the next tree, you didn’t scrape enough), and then give it a year. Check back now and then to be sure you didn’t miss any tissue in the gap and to remove any vigorous suckers, but it will kill itself soon enough. We’re killing hundreds each year, and the native vegetation is slowly recovering.

@alisonnorthup is working with me to have volunteers test several different ways I’ve learnedcto girdle—some I’ve been taught and others I’ve developed on my own. In about a year, perhaps less, we should have results to report.

Then we’ll test different approaches to girdling chinaberries and Chinese pistache. Perhaps because of features they share as members of the mahogany family, they resprout vigorously from below the girdled gap. We’ll see if we can figure out a technique that is appropriate for volunteer projects and close to 100 percent effective.

Posted by baldeagle about 2 years ago (Flag)
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We see more Four-spotted Palpita, Palpita quadristigmalis, here (NW Austin) which is also reported to use privets. Kinda makes me wonder if these Palpitas are truly native to North America or if they were brought over on the plants long ago. In any case, they would need to be pretty prolific breeders to put a dent in the massive invasive plant population.

Posted by earthgrazer about 2 years ago (Flag)
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@sambiology In your first observation link, it's hard to really see details of the damage, but it doesn't look like insects caused it. Lots of other tree diseases can cause wilting and defoliation.

Posted by nanofishology about 2 years ago (Flag)
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I've raised Spilomelinae moths from caterpillars a few times (Psara spp.) and they are pretty easy. The ones I had were eating pokeweed.
https://www.inaturalist.org/observations?q=JP-0817&search_on=tags
https://www.inaturalist.org/observations?q=JP-0717&search_on=tags

Posted by nanofishology about 2 years ago (Flag)
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In March of last year I had several P. atrisquamalis adults show up between a kitchen window glass and the screen. I assumed the cats had climbed in there and pupated, and now the adults were stuck. I freed them, of course. But it IS interesting to note, the plants right outside that window are all privet. Didn't notice any this year, but I'm blacklighting closer to that location now so I'll keep my eyes out. I'm always interested in documenting the life cycle of a lep species.

Posted by kimberlietx about 2 years ago (Flag)
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Sam, this is exciting news. What a great opportunity for citizen scientists. I'm on the hunt for caterpillars

Posted by hombrefrutas about 2 years ago (Flag)
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@nanofishology, did you see the webs in @sambiology’s first picture? It does look like that was caterpillars at work—but unfortunately they don’t seem to affect the production of berries at all. 😕

And I trust y’all know that my statement above somehow lost the “in cheek” near the beginning. 😬

@earthgrazer wondered if perhaps these moths are themselves invaders and came over here with the privets. The abstract @sambiology cites from a Chinese publication makes it clear that they are a new pest over there. If they are killing quihoui privet in China, perhaps it’s because they lack the natural predators they have in their native range, wherever that happens to be. Maybe they aren’t so prolific—they’re just out of balance over there. Darnit. (Kidding, Chuck!)

Posted by baldeagle about 2 years ago (Flag)

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