I understand that a teneral is an insect that has recently molted, and is distinguished by being soft and pale. However, I only see the term regularly applied to a few taxa, usually Odonata. On iNat the “teneral” life stage is only an option for a few taxa as well.
However, don’t all or nearly all insects go through this stage? Is there something special about those taxa?
Hi,
If you go to this thread: https://forum.inaturalist.org/t/lets-talk-annotations/
and search the word “teneral” (make sure you search “in this topic” only),
you will find a vigorous discussion about this, including the definition of teneral.
I think it’s just that it’s rare for people to notice that stage in other insects, whether because they go through it faster or because they’re hidden somewhere people won’t find them as they harden.
Other related threads:
In myrmecology it’s called a callow. I take a particular liking to seeing callows so I call them out when I see them.
I don’t know for certain, but my guess is that for certain taxa, it’s a (largely) pointless distinction between teneral and adult. Determining exactly when it ceases to be a teneral and becomes an adult would needlessly complicate the annotation process without providing much in the way of useful information.
I believe this would be the case with butterflies. I guess you could identify newly emerged adults whose wings have yet to fully inflate as tenerals, but at what point does it stop being a teneral? What about a butterfly that hasn’t successfully inflated its wings? Can we distinguish them from true tenerals in the average iNat photo? Even if you resolved that difficulty, what would it really tell you? Considering how we use life stages for butterflies, if the teneral phase lasts a few hours at most, treating it as a separate life stage doesn’t really affect anything like flight season charts. Is there any point to all of this when there would only ever be a handful of tenerals reported? (I’ve seen very few and I review ~50,000 observations per year)
I think one should look at how life stage annotations are used to determine if this is a meaningful distinction for the taxon in question. You want adults identified as such so that you can document flight seasons (which can inform identifications). You want larvae separated from pupae so that you can, for example, look at host plants that may be part of the observations.
I once got into an argument with someone about whether a butterfly larva that was hanging upside down was a larva or a pupa. Their position was that it was neither - it was a pre-pupa. Even if it’s objectively true, is there any point to this level of hair-splitting? Will this really affect anything?
Note that the answer to these questions can change. Perhaps someone will come along and say “I am doing research on butterfly tenerals, why haven’t you been annotating them as such?”. That’s a risk. But we don’t have unlimited identification/annotation resources. We can’t document EVERYTHING. We have to allocate our resources as best we can based on what we currently think is useful. We may end up regretting our decisions down the road. Or perhaps we’ll just shrug and say “Yeah, we could have documented those, but there would only be a few dozen at most so quit complaining”.
I’m currently going through a large review of old observations for one genus, and re-identifying them as necessary based on updated taxonomy and criteria. While I’m at it, I’m adding the sex annotation so that when I’m done, I’ll have a large dataset of annotated observations that we can then assess to see if the taxonomy/phenology/criteria that I’ve applied “makes sense”. Partway through the review, I realized that since I’m having to look closely at the photos to sex them, I might as well (roughly) document the degree of wear as well. This might be important for explaining outliers when we chart the phenologies. So now I’m backtracking to add a “wear” field to all the observations I had recently ID’d and sexed. Should I document sex/wear for other species - at least for observations I’m IDing going forward? Ideally yes, but that will slow down the ID process. I already spend way too much time on IDs, so I have to pick my battles. Currently, I only annotate the sex for certain species where I think it might be useful. I only document the wear for extreme outliers that might otherwise appear way out-of-season.
I guess my point is that there’s no simple answer to a question like this. Nothing is without cost. You have to balance the cost of documenting something against the foreseen/potential benefit. I think that for some taxa, documenting tenerals is either not worth the bother, or doesn’t make sense for some other reason.
It is a term used frequently for beetles. It can explain why the beetle is not the colour you would expect. It is also useful for indicating the time of year the adult beetle emerges, which isn’t often observed compared to butterflies and dragonflies.
Was just explaining why the term isn’t normally used for some groups like butterflies. I get that it is useful for others.
Considering the observation that you only see the teneral phase applied to certain taxa, and your question if there is something special about those taxa which it is applied to: it seems indeed pretty random, impractical and even unfair why some life stage annotations have been accepted and implemented, like the teneral stage in odonata and the subimago stage of mayflies (when it just emerged from the nymphal skin and the wings are not transparent yet, typically lasting just for a few hours up to one day), while for example the very obvious immature life stage of birds (which may last many years) still has not.
Apparently, there is a need and preference to precise the very brief stages of some insect groups, but in birds it suddenly does not matter anymore if it is a juvenile or immature, and iNaturalist seems too reluctant to even consider its implementation, despite many remarks in the years-old topic about annotations. Juvenile and immature (and even hatchling/chick) are very distinct life stages in the vast majority of birds and serve different biological roles (chicks presenting a downy plumage, juveniles having attained the first real plumage after the downy stage, and immatures being anywhere from the second prebasic molt onwards but not yet fully adult, which can last up to a few years in larger birds), while one could argue that the teneral stage in odonata is not even a different life stage but just the first few hours or days of maturation as an emerging adult, and any teneral odonata would in that sense be correctly annotated as ‘adult’.
After years of using iNaturalist, I cannot wrap my head around why some obvious life stages like ‘immature’ for birds are still not implemented while green light has been given to some less logical life stage annotations like ‘teneral’ for odonata.
All insects have that teneral stage, regardless of what it is. Only a few basal ones may not have it.
Think about it as an adult with an exuvia. Teneral isn’t a life stage; it is just the hardening of the adult exoskeleton.
I had some comments here, on a flag asking for a general life stage: https://www.inaturalist.org/flags/841082
I hope this is useful.
However yes iNat needs to allow multiple life stage like evidence of presence. Treehoppers and shield bugs often have colonies with both adults and nymphs in one place. How can someone annotate that? (Note: I’m not an annotator though so idk whether they got workarounds.)
Cicada exuviae are also common on iNat, what do they annotate it as? Alive/dead? is exuvia evidence of presence? idk.
iNat usually starts with the idea that an observation is for one individual only, so if you have a photo of a colony with both adults and nymphs present, your observation would still count for only one individual in that colony, which is why only one life stage annotation is permitted, as one individual cannot be nymph and adult at the same time.
nymph - exuvia + adult - teneral. This is the case here.
And then am I supposed to count every one? I really would not say so!
Agree with you @aaravmishra: the exuvia is just the leftover exoskeleton of the nymph and not really a different life stage, and the teneral phase is the start of the adult stage, and so technically not a different life stage either. Of course you are not expected to upload 50 different observations if, for example, you encounter a group of 50 woodlice beneath a fallen branch, but the idea of one single iNaturalist observation is that it is destined to one individual, and so only one life stage annotation is permitted, which is a logical and defensible choice.
I think the staff should allow a new annotation that is singular/gregarious/parental care (when a bug protects its eggs giving two life stages). Gregariousness and parental care in insects is a topic of research and it could be useful.
Parental care could be indicated as such in the observation field section, not necessarily as a life stage annotation, just like the teneral stage for dragonflies could be annotated as ‘adult’ and further specified as ‘teneral’ in an observation field. An immature bird, on the other hand, is actually in a different life stage than juveniles and adults when it has started to replace its juvenile flight feathers in the second prebasic molt but is not yet fully capable of breeding like adults, and in a fair amount of species, it even has a different plumage aspect than juveniles or adults of the same species.
I know this doesn’t fix the perceived injustice part, but as a way to get on with getting useful work done, why not use an observation field? Fields don’t have the same functionality that an annotation has, but for most intents and purposes, they get the job done.
One advantage that a field has over an annotation is that you can’t correct an annotation that someone else set. Other users can only downvote the incorrect annotation. With a field, anybody can change the value. That means if it is set incorrectly, it can be overridden (of course, that cuts both ways, but I’ve rarely see anyone alter a field value that I have set).
You’re probably already aware of it, but there are already 2 different versions of “Bird Life Stage” fields defined. If neither one offers a range of possible values that suit your needs, you can create another version.
One downside to fields is that some observers set their preferences to block others from adding fields to their observations.
Again - there’s a field for that. If you don’t like one of the various ones that already exist, you can create a new one that meets your needs. For your example, you could add the following fields (which already exist in iNaturalist):
Insect life stage: Adult = Yes
Insect life stage: Nymph = Yes
That’s two fields. A bit tedious if you have to type them in, but you can always use the Metadata tool to create shortcuts that add these fields with a single key stroke. Another (somewhat cruder) way is to add some kind of freeform field and type in “observation contains two life stages - adult and nymph”.
These options work for me because I am usually both the source and sink for the fields in question. These are essentially conventions I’ve made with myself. I (mostly) don’t have to worry about somebody doing it wrong. I try to make them as straightforward and intuitive as possible so that other people can use them in the same way, but at the end of the day I’m entering the information when I review the observation so that it’s there for me to harvest at the end of the season. If you’re not the intended “audience” for the information, it’s hard to know what the best way is to enter it. One approach is to ask owners of projects that are somehow related to the taxon in question (“How do you guys want me to annotate something like this?”), or just look for how other observers have handled similar situations.
Since you say you have no intention of doing annotations, I’m not sure why you’re agonizing over it. Many projects have set up their own guidelines for how they want various things annotated. Unfortunately, they rarely seem to make any effort to re-use existing fields. Everyone creates their own and mutually incompatible annotation/field conventions. That’s one advantage of annotations - there’s an element of enforced conformity. With fields, everyone can do whatever they want and it shows.
Pro-tip: It is often helpful to use a field that mirrors an annotation. In cases where someone has set the annotation incorrectly, you can apply the corresponding field with the correct value (vs trying to get the user to change their incorrect value). It also allows you to apply whatever options you feel are missing from the annotation. For example, the “sex” annotation only allows Male, Female and Unknown. But the “sex” observation field allows an additional value - mixed, which is useful for observations that contain both sexes. I use the sex field for these cases, and for cases where the sex annotation is set incorrectly. My software that harvests observation data gives precedence to whatever value is in the sex field over the sex annotation. In case where I’ve added the field because the corresponding annotation is wrong, it could theoretically serve as a prompt to whoever set the annotation incorrectly. I don’t know if this has ever actually happened. I suppose I could check to see if there are any cases where I’ve added the field and the annotation has the same value - that would be a clue that at some point, the annotation must have been corrected, but I’ve never bothered checking.
This topic is primarily about the teneral stage (of dragonflies and other insects) and not about birds, so sorry to the creator of the topic for digressing towards birds too much, but as a comeback to your remark and also coming back to the teneral stage: no, observation fields do not get the job done for most purposes. If observation fields were the solution to getting things done, why not drop life stage annotations altogether? Because life stage annotations and observation fields do differ significantly in use.
The annotation is to quickly indicate the life stage of an organism and can be used to browse through photos of a certain species displaying only individuals that are in the selected life stage. If you can only choose between egg, juvenile and adult, you miss two life stages in birds (chick/pullus and immature). For example, a second-cycle or third-cycle European Herring Gull cannot currently be properly annotated, because it is neither an adult nor a juvenile but an immature, and as a consequence, you cannot browse through photos of European Herring Gulls only within that life stage. If you set the life stage to ‘juvenile’ in the photo page of European Herring Gull, you will get anything from pulli to first-cycle juveniles and later-cycle immatures mixed together. An observation field does not solve this photo browsing problem but providing the obvious option ‘immature’ as a life stage annotation for birds, will solve this.
Even though technically speaking the teneral stage of dragonflies is not a different life stage, I am still glad that the annotation exists, because it makes it easier to display photos of individuals of a certain species precisely in this teneral stage. For birds, this would be very helpful, too. Sure, ageing mistakes will be made but annotating an immature bird as a juvenile is actually also a mistake, whereas annotating a teneral dragonly as adult is still fine.
Fair enough. I wasn’t aware of this wrinkle because I never browse photos in iNat.
Only annotations work on the Photos page, but both annotations and observation field values work in the Explore and Identify pages. Is there something specific you’re trying to do that only works with the Photos page?
But there are eggs too! And yes I’m not making observations for every egg.
obs. fields vs. annotations.