Among the more conspicuous insects of springtime, at least in the western U.S., are true bugs known as “bordered plant bugs” in the family Largidae. The most obvious of these are in the genus Largus, but they are readily dismissed as simply another kind of “stink bug.” They can also be confused with certain leaf-footed bugs in the family Coreidae, or even “cotton strainers” in the family Pyrrhocoridae. In fact, at one point, largids were classified in the Pyrrhocoridae.
Adult Largus are fairly sizable, at 13-17 millimeters for L. succinctus for example. Most of the twelve North American species are black, with orange trim, and varying degrees of orange speckling.
The nymphs, on the other hand, are a lovely metallic blue, with a central bright red spot on their back (though first instar nymphs are wholly blue-black, or red in the case of L. californicus.
The adult bugs overwinter, females laying eggs in clusters on the ground, an average of 130 per cluster for L. californicus (Booth, 1990). Booth’s study in coastal southern California showed that eggs hatch in about 14 days. Nymphs progress through five instars, an instar being the interval between molts. Approximately 100 days are spent in the nymphal stages. Adults, which are flightless, live from two to seven months. There are two generations of L. californicus annually.
Nymphs often congregate in groups of 100 individuals or more, probably for the purpose of amplifying their “warning colors” of blue and red. Indeed, apparently some lizards find largids distasteful. I have personally observed large congregations of Largus nymphs and adults in Arizona and Vancouver, Washington. They are quite a spectacular sight. Reports of other species suggest eggs are laid on host plants, with other differences in the timing of the life cycle outlined by Booth (Deans, et al., 2011).
While the bugs are generalist feeders on a variety of plants, they occasionally eat fecal material and carrion, too. Indeed, many herbivorous Heteroptera appear to be opportunistic scavengers in my own observations.
There is rampant disagreement as to exactly how many species of Largus there are in North America, since many “species” have, in the past, been described based on color pattern and geographic distribution. These insects are of little economic importance, so correspondingly little research has been conducted on them.
The greatest diversity in the genus is in the southwest U.S., but species are collectively found across most of the U.S. L. succinctus is apparently the sole eastern species, north of Florida anyway. It ranges from New York to Florida, west to Minnesota, Oklahoma, Colorado, and perhaps Arizona.
Sources: Booth, Carey L. 1990. “Biology of Largus californicus (Hemiptera: Largidae),” The Southwestern Naturalist 35(1): 15-22.
Deans, Andy, et al. 2011. “Insect of the Week – number 74,” Insect Museum blog of North Carolina State University.
Henry, Thomas J. and Richard C. Froeschner, Eds. 1988. Catalog of the Heteroptera, or True Bugs, of Canada and the Continental United States. New York: E.J. Brill. 958 pp.
Slater, J.A., and R.M. Baranowski. 1978. How to Know the True Bugs. Dubuque, Iowa: Wm. C. Brown Company Publishers. 256 pp.
We have these in California as well. I only noticed them 3 years ago.ReplyDelete
I saw one yesterday in San Luis Obispo, CAReplyDelete
Do the the tiny red Largus hatchlings damage plants?ReplyDelete
Large numbers of them can probably weaken a plant, but I am not aware of these insects being regular, significant pests.Delete
Found a Largus nymph in west coast Florida.Delete
Are they harmful to petsDelete
These guys are absolutely incapable of causing any harm to pets or humans, and you would have to have a drastically huge number to notice any damage at all to vegetation.Delete
Here in Northern California, the nymphs feed on our few raspberries and the adults congregate and feed on our small pumpkins, sucking them dry from underneath. Really frustrating...ReplyDelete
I do wonder if the pumpkin-ators are another kind of bug, like a squash bug.Delete
When they show up on the pumpkins, to help identify them, I'll have to take a flick before I squash them! They don't show up every year, so we'll see, but the nymphs are sucking the juice from the raspberries already.Delete
Almost surely a different species of bug, such as Pentatomidae species. Largus bugs cannot suck a fruit dry.Delete
Yes, they seem to be intelligent because they know when I'm looking at them (like roaches!). It's hard to believe they are harmless...something is putting holes in my plants...although they appeared with the white flies, so let's hope they eat them.ReplyDelete
They are NOT "harmless". Why do people continue to say that? These little bastards will destroy any berry crop you have. They totally ruined my mulberry crop this year. Every single berry was sucked dry.ReplyDelete
What is the best spray to KILL them??
I can confirm these are in Cottonwood, AZ, in my backyard!ReplyDelete
this year only I have lots of the small blue metallic beetle with red dot on the back. Are they bad for my plants?ReplyDelete
They are *not* beetles, they are still true bugs, just the nymph (immature, juvenile stage). Beetles and bugs are two different insects entirely...No, they should not be bad for plants, but if you get large numbers you might just pick them off or use a jet of water to get them off and into a bucket of water.Delete
Forgot to say I am in Chico CaliforniaReplyDelete
This is the first year I have seen the little blk metallic a/red dot, but they are everywhere!!! Along wth the adults , which are "butt-to-butt" everywhere too! Tonight, as I was watering, I noticed the nymphs & adults were all on a strawberry in one of my berry beds. Should I be concerned? I'm in Coarsegold, CAReplyDelete
Up to you whether they are problematic or not. In large numbers they can probably impact a plant negatively, but we underestimate the ability of plants to rebound after assaults like that.Delete
Shasta, cal. These pests,in 6 weeks, have taken over a huge yard. They are on the outside of house...on the ground..everywhere. 1 mo. ago, after a tree was felled, on the stump were masses of the tiny ones,in piles be all around an inner ring below the bark. They were eating it. Have sense verified that they don't just eat fruit, and leaves; they eat woody part too. Destroying a 20 year old,slow growing,japanese bush. Eating all of the spireas also, and part of a plum tree. The comment that they are not harmful is nonsense. Until 6 weeks ago, I had never seen one here.ReplyDelete
The fact you had never even seen a single specimen until this year speaks to the fact they are NOT pests. Your number came up this year. That is all. Relax. Your "Japanese" bush is what is out of place. Please try landscaping with native plants.Delete
Shasta county CA: They are eating all the tomatoes, strawberries and raspberries. Stopped even bothering to water. Nothing seems to deter them. Not Sevin, or exterior house perimeter barrier bug spray.Delete
Are these new bugs?
Are these native to CA.
What makes you think they wont stick around for next year?
What makes them move on.
Are you sure they will move on?
Is there anything that does keep them off of produce plants.
Thank you for your post. I didnt find any other sites come up for this bug. Of course, I was search for a blue beetle.
Anything that eats an entire seasons crops is a pest. They are even getting into the house. What next? My fruit bowl? If they don't move on I am getting a howitzer. And honestly it doesn't seem right to just ignore them this year so that millions more next year can move on to the next town. These may not have the numbers to be a pest in the past or perhaps they stayed in the woods to eat. We had a fire here 3 years ago. 100,000's of thousands of wooded acres destroyed. National guard stopped it entering my "city". Is that part of whats happening? If so, we still have 100's of thousands of wooded acres.
These are most definitely native insects, IF we are talking about the same insect. Without seeing specimens I cannot be certain. Please consult your county's Cooperative Extension Service, and/or your state agriculture department to help you cope. I appreciate tolerance and acceptance here on my blog, not complaints nor accounts of how you have already tried to exterminate something. Thank you for understanding.Delete
These nasty nymphs are destroying my Strawberry plants here in Western Washington. How do I get rid of them? They are small black with a single red dot. They do move fast.ReplyDelete
I'm sorry you are having issues, but you must not follow this blog regularly, as I NEVER suggest ways to "get rid of" any species. They all have their place. Thank you for understanding and respecting that view.Delete
I've lived in rural Shasta county, with a large garden, berries and fruit trees, since 2008. I first started seeing these bugs about 4 years ago. Every year there are more. They are very alert and will hide once you start disturbing them. They will eat anything they can and destroy your fruit crops. They are a very big pest of all berries, tomatoes, corn (eat the silks) and stone fruits. Fortunately one of their defense mechanisms is to fall when disturbed, so I can collect several hundred in a bucket in short order. I have yet to try soapy spray, which I've heard will kill them. They have also found our date tree and are all over it. They are not to be taken lightly. I suspect that we are missing whatever eats them... It seems like pests in the garden are generally cyclical, and you never know quite what to expect. But these have been constant for 4 years.ReplyDelete
I truly appreciate you sharing your experience. I try never to "censor" anyone who has this kind of story to convey. I wonder if climate change is aggravating this kind of phenomenon....Delete
Michael in Southeast Louisiana. I think I have the same bug.ReplyDelete
Dark brown almost black, lateral orange stripe across the shoulder. It surprised me while I was tending to my tomatoes.
It did not have a solid orange edge, on both sides down to its "tail", it was more like orange dashes. I would shoo it off. Then about an hour later, I found it back in the same spot on my tomato plant. I shooed it away again, and then it returned later, to the same spot. I tried to catch it, but it did not survive the ordeal. I do have pictures. I also found a leaf on the next plant over that had eggs on the bottom. I do not know if it was a "momma" bug staying close by.
We seem to have these bugs and they seem to be chewing right through our artichoke plant stalks here in the Central Coast of California. Black, red spot on the back. Any advice to control damage on our artichokes? That's the only place we've seen any real damage so far. Thanks!ReplyDelete
Adults are not flightless. I just saw one fly myself (and hasten to add that, being familiar with native large heteropterans, did not misidentify it as some superficially similar genus).ReplyDelete
I'm in Tehama county California I noticed these little buggers last year decimated all my crops they suck them dry. This year Aug 2022 I have a grove of Eucalyptus and there must be nearly 2 million in that area I'm afraid they will destroy my crops yet again. These are very smart bugs.ReplyDelete
I just noticed these nymphs while doing some yard work. I also saw the adult version. I had never seen the nymphs before until yesterday. Is there a common name for them, not just Largus? I live in Coarsegold(Madera County). Thank you.ReplyDelete
Mere gharpe bohot sare hainReplyDelete
Gold Canyon Arizona , near the Superstition Mountains - first time I've seen one of these out here was the other day. A bug identification site indicated the one I saw was an Eastern bordered plant bug. It was a very nice insect, seemed to be sentient, was very aware of me but hid instead of running away, and came back out when I backed away. Handsome critter!ReplyDelete