Curculionidae Trichosirocalus barnevillei?

[JRsbugs]

Hi.

This is the closest I have found, the pattern does seem to be slightly variable but the general pattern seems to fit as does the shape. I'm prepared to be told otherwise though!

I found it on Ribwort Plantain growing under Hazel, I wouldn't have seen it if I hadn't been taking pics of a sawfly larva which was ~9mm long, the beetle was under 3mm. It was also difficult to take pics of as the wind was blowing so this was a one handed effort.

I turned the back view upside down in one pic as that is how they are seen in pics on the internet, makes it easier to see the shape.

Janet

[Klaas Reißmann]

Hi Janet,

everything fits for Trichosirocalus troglodytes.

Regards
Klaas

[JRsbugs]

Originally Posted by Klaas Reißmann

Hi Janet,

everything fits for Trichosirocalus troglodytes.

Regards
Klaas

Hi Klaas,

You know I was about to accept that you will be correct, thinking the pattern must be more variable than I am seeing on Trichosirocalus troglodytes.

There's a big but though! Check the photos with the two species side by side on this site, you can see the head shape of Trichosirocalus barnevillei fits that of mine. The eyes are also set at the front of the head, on troglodytes they are longer and are set towards the back of the head..

Please take a closer look at the head..

[Klaas Reißmann]

Hi Janet,

the pages of Claude Schott are very, very nice and I often take a look on those pages to compare weevils I haven't seen yet with those I found and which are going to make problems by identifying them.

One of the very important characters of T. barnevillei can be seen more or less good on his pages. This character is a hair coat on the front between the eyes that is missing in T. troglodytes. And in your pictures it is missing, too.

Maybe it is easier to see it on the pages of Christoph, because he is giving much larger photos. Use the comparing machine on his pages and I'm sure you will see what is meant.

The pattern of Trichosirocalus is a difficult character. Those weevils loose their pattern quite easy. Especially most of the T. troglodytes I find outside arrive at my home with the loss of more than 80% of this pattern. So T. troglodytes itself can appear quite different.

Regards
Klaas

[JRsbugs]

Thanks for the clarification Klaas... but I am even now more certain it is Trichosirocalus barnevillei.

I have lightened my pic which does show hairs, in fact they are in the same places as the pic of Trichosirocalus barnevillei on Christoph's site. The head on T. barnevillei looks to be longer to the pronotum margin, the angle at which the snout joins the head is a much more gradual curve, the eyes do look to be the same distance from the pronotum as mine does, all these things match to my eye spot on. The hind margin of the pronotum is also curved on barnevillei, the same as mine is, where on T. troglodytes it is more straight.

I did as you said, put both species side by side and also put my pic in line with them. I'm sorry to say I can't see the likeness to T. troglodytes at all, the likeness to T. barnevillei is exact. There is another pointer I noticed, that is the bulging end of the (first?) long antennal segment which joins at the right angle to the remaining segments which mine has.

One more point, is T. barnevillei less likely to lose hairs than T. troglodytes? I think not, but mine does have the hairs, they are not as highlighted by flash as those on Christoph's site but you can see them, and I did notice hairs between the eyes of T. troglodytes also. Surely the main characters to look at are the shape of pronotum, head etc.?

Here's the lightened pic, if you compare all three together as I did I feel sure you might now be able to see what I mean.

[Klaas Reißmann]

Hi Janet,

I do know what you mean, but it doesn't help. I try to make it point for point in order to what you wrote:

1. Your photo only shows hairs along the inner border of the eyes. Maybe a few (three or four) hairs on the front between the eyes which is typical for T. troglodytes. T. barnevillei needs a dense hair coat, covering around 90% of the head between the eyes.

2. It looks like the head of T. barnevillei is longer than the head of T. troglodytes. But this is, because the T. troglodytes is holding his head up straight, the T. barnevillei in both pictures, yours and Christoph's is holding his head down. You can see the hindhead which you can find at T. troglodytes, too, if it is holding his head down. You even do not find this as character in books, because both species are the same in this.

3. The distance of the eyes to the pronotum is the same problem: holding the head down.

4. The antennal segments are so blurred and hidden in reflexion of the flashlight and even hidden in the darkness of the background that you can see everything you want or not. Another problem here is again, that both species hold their antennae so different, that you have no chance to compare this in the photos. You would need photos of dissected beetles that show exactly the same position.

The main characters are the dense hair coat between the eyes. All the other characters are useful to confine the very similar T. rufulus, but not to confine T. troglodytes.

Some other points that are inportant and that show yours is a T. troglodytes:

1. The colour of the elytra in your pic is shining reddish (reddish-brown). This is typical for T. troglodytes. T. barnevillei is coloured light brown, bar far not as redish-brown as T. troglodytes.

2. Last but not least you found it on Ribwort Plantain (Plantago lanceolata) which is the breeding plant of T. troglodytes. T. barnevillei is breeding on Achillea millefolium and more rare on other like Tanacetum and Anthemis. If T. barnevillei is a species of the UK, have a look in sandy areas for Achillea millefolium and you might find T. barnevillei.

I'm sorry I can't make a T. barnevillei of this.

Regards
Klaas

[JRsbugs]

Originally Posted by Klaas Reißmann

Hi Janet,

I do know what you mean, but it doesn't help. I try to make it point for point in order to what you wrote:

1. Your photo only shows hairs along the inner border of the eyes. Maybe a few (three or four) hairs on the front between the eyes which is typical for T. troglodytes. T. barnevillei needs a dense hair coat, covering around 90% of the head between the eyes.

2. It looks like the head of T. barnevillei is longer than the head of T. troglodytes. But this is, because the T. troglodytes is holding his head up straight, the T. barnevillei in both pictures, yours and Christoph's is holding his head down. You can see the hindhead which you can find at T. troglodytes, too, if it is holding his head down. You even do not find this as character in books, because both species are the same in this.

3. The distance of the eyes to the pronotum is the same problem: holding the head down.

4. The antennal segments are so blurred and hidden in reflexion of the flashlight and even hidden in the darkness of the background that you can see everything you want or not. Another problem here is again, that both species hold their antennae so different, that you have no chance to compare this in the photos. You would need photos of dissected beetles that show exactly the same position.

The main characters are the dense hair coat between the eyes. All the other characters are useful to confine the very similar T. rufulus, but not to confine T. troglodytes.

Some other points that are inportant and that show yours is a T. troglodytes:

1. The colour of the elytra in your pic is shining reddish (reddish-brown). This is typical for T. troglodytes. T. barnevillei is coloured light brown, bar far not as redish-brown as T. troglodytes.

2. Last but not least you found it on Ribwort Plantain (Plantago lanceolata) which is the breeding plant of T. troglodytes. T. barnevillei is breeding on Achillea millefolium and more rare on other like Tanacetum and Anthemis. If T. barnevillei is a species of the UK, have a look in sandy areas for Achillea millefolium and you might find T. barnevillei.

I'm sorry I can't make a T. barnevillei of this.

Regards
Klaas

Lol, this is a good exercise on how difficult it can be! I have to bow to your expertise Klaas, after all you must have been examining these for a long time. I see you points!

I do have a lot of Achillea millefolium .. some very good patches actually in my garden which are doing very well and I get lots of interesting insects on it. but there are plants here and there besides. My ground is very sandy, old river bed. Actually, the Achillea is not in flower yet but does that make any difference? Do the larva feed in seed heads?

There are still two points not addressed though.. the fact that both species are likely to lose hairs, and the curved shape of the hind margin of the pronotum.

I'm not sure I agree I am making what I want of the antennae either.. on T. troglodytes in Christoph's pic the 1st long segment looks nearly the same width, maybe only slightly thicked at the end. I've cropped and lightened the pic even more.. it still looks very swollen to me. But, there's always a but..

[JRsbugs]

One more note, yes we do have T. barnesvillei here and records on the NBN are not far south of me on the east side. I usually get species which are said to be only south of the invisible line drawn from the Wash to the Severn.. which is where the records are up to. Rarity is no stranger to me either.. although there's one or two people here who might try to prove otherwise.

NBN Gateway - interactive species mapper

[Klaas Reißmann]

Hi Janet,

many larvae of weevils feeding on herbs are fed on the roots or parts just above the soil. At first it makes no difference if the plant is in bloom or what ever (in reality it does make a difference, because the plants are often needed at a special period of life). One of the most important facts for phytophagous beetles one should follow is, that those beetles are parasites of indulgance. So when you do have an area with a lot of plants growing in a group, this place must be of good condition for the plant and it is to estimate that those plants are fit, or you will find the ones of this group that are not fit at the border of the group.

Others standing alone, next to a dirt track, maybe people or animals always stepping on them, those who have a waterproblem and other things, that are the plants that are fainted and that can not defend themselfs and which are the right victims for those beetles (many butterflies f.e. need the young leafs of trees and bushes for their larva, because the old ones comprise to much antibody).

So standing on sandy ground is possibly not enough. Have a look for plants that look like needing water, because of possibly drying of, that are standing next to a dirt track, that have other problems, f.e. many holes in the leaves, because of other insects feeding on them and so on. I guess you well have more success in surching at those plants than at any other.

I always notice it f.e. with Hadroplontus litura. It is always a weevil you can find, because it is not rare. But I have been surching at hundreds of thistles and after many years I found my first on a thistle (my real first ones I found in winter when I was filtering moss growing under broom), a few minutes later the second and started to ask myself "Why there?", "Why not somewhere else?" and found the reason very fast: it was always the thistles standing at the border of a dirt track and always those, that didn't grow in groups, but all alone (the next thistles haven't been 10 cm, but 40 or 50 cm away from the one with Hadroplontus).

Maybe that gives an idea of what is going on. The better you see problems the more you will find phytophagous beetles (and other phytophagous insects).

To your questions:

The curved shape of the hind marging of the pronotum again is a problem of the perspective of the photo or the beetle holding it up or down. If you compare the two species on Christophs pages, you will see, that those margings are the same. There is no difference in habitus of the pronotum or the whole body.

The antennae is still very blurred. I know what the first segment after the scapus must look like. I can see the segment the way it is. But I guess I understand what you mean what you see. I wish I know how to send pictures to this pages. I would download yours an paint the way it is and even the way I think you see it. And maybe you see what I mean.´

But how ever. Don't be to impressed by my expertise. Even I do have a lot experience I'm not always right. I do mistakes as any other. And if there is any disbelief you should go on asking and surching and digging deeper. As long as I'm able to explain I will try to give an answere. Never mind how much work this will be in writing English. It's hard, but my experience in English grows, so what can I wish more.

Regards
Klaas

P.S.:

1.

I have to bow to your expertise

No, you don't have to. Much more I do have to bow to your constancy and to your will to learn and to understand. It is easy, when you know things. It is much harder to learn new things and understand them.

2.

after all you must have been examining these for a long time

I guess this is the question for "how long do I do this". It is easy, when you are able to calculate : I started collecting shells and snails with the age of 10 (I did a lot in South Devon in the area of Kingsbridge, Salcombe, Bigbury-on-Sea (South Hams) - I can remember town names like Frogmore, Torcross (there is a cliff directly south of Torcross I loved very much!!!) and a nice pottery in a small town I can't remember the name (maybe Chillington), producing cups with a frog on its bottom ) and changed to butterflies when I was twelve, doing nearly everything with insects when I was fourteen, having a little break from 23 to 25 and changed to the beetles doing nothing but beetles. Today I'm 43, in a few month 44 and know: it is a very long time...

[JRsbugs]

Hi Klaas

Thank you for your patience, and your time! I see you have lived here! You have been doing beetles for a long time, but you are not yet that old! Plenty of years to do more yet. I have only been taking a keen interest in insects etc. since I got a digital camera and a decent computer, that was a little over 6 years ago now and I'm a good deal older than you. It was a gradual awakening which accelerated when I got a digi DSLR camera and I got that because I needed to take better pics of insects! I fed my habit with an insatiable desire to know more but I guess you have already found that out.

It's interesting to find that beetles prefer the struggling plants, I have one or two struggling Achillea millefolium growing at the base of an Oak tree which is in my garden and overhanging a roadside drain, not far from where I found this beetle. I will be keeping an eye on that plant.

You can easily upload pics here by going to the 'Images' tab on the top bar. There you click on "upload photos' and you will get this. Select a category to put the photos in and the rest is quite straight forward. When you make a post in a thread such as here, after your typing place the cursor to a new line as you would for a paragraph. Then click the icon on the right side box which says "Library Images". This will bring up your latest loaded pics, click once on the pic you want and it will go into your post, you can place 5 pics in a line across the page with a maximum around 1MB for each pic. The thumbnails will show in a 'preview'.