blunt-tail larva - Dirrhagofarsus ernae

Moved

Moved from Dirrhagofarsus.

… Robert Otto, 22 October, 2014 - 10:46pm

Moved

Moved from False Click Beetles.

… Jim McClarin, 1 June, 2007 - 5:31pm

Moved

Moved from Nematodes penetrans.

… Jim McClarin, 6 February, 2007 - 4:19pm

likely Nematodes penetrans

From Jyrki Muona, Jan 28, 2007:

Jim,

They had arrived last week - really fast! Now that I had the larvae at hand, the situation changes. Somehow one just misses things when looking at images only. First, this is not a described one [meaning larva]. Second, combining the t-formed rods on the prothorax, the few lateral teeth on the head, the pointed spiracular collars and the peculiar last segment makes them characteristic. The similarity to an undescribed Nematodes I bred from Viti Levu are striking and I am fairly sure this is Nematodes penetrans, which, as far as I know is not recorded from NH [not so], but is from Maine and about all the surrounding regions. What makes this tricky is that all Nematodes actually have three different larval forms. The first minute larva is "Melasis-like", soft with large manibles, the second one like yours and the third, prepupal one, entirely different again, poorly sclerotized etc. One thing that makes me wonder is that often Nematodes breed in fairly hard-appearing wood, although at the time the larvae are bigger, the wood usually is soft already.

Please, try to breed it or put a window-trap close by. It would be nice to find out. After all, there are several undescibed "larval genera" you could have, e.g. Sarpedon, Epiphanis etc.
s.
Jyrki Muona

… Jim McClarin, 28 January, 2007 - 1:40pm

Moved

Moved from False Click Beetles.

… Jim McClarin, 28 January, 2007 - 1:37pm

Eucnemid authority Dr. Jyrki Muona says

he suspects this is a larval Micro*rhagus subsin*uatus, which would be a new species for New Hampshire. However, I am shipping him some similar larvae from the same source in a vial of alcohol so he can make a better determination. Meanwhile I hope that at least some of these will mature so I can add adult images.

… Jim McClarin, 20 January, 2007 - 10:52am

Let me redeem myself.

Maybe my first guess at size was not completely outrageous. This larva has apparently burrowed into something and can't be measured. However, in searching through some white-rot sapwood I brought home from the trunk section in which I found this one I found an 18.5mm larva of the same type. I'm changing the size for this one to that figure, more in line with my original 20mm estimate.

… Jim McClarin, 11 January, 2007 - 7:59pm

Wow!

Thanks, Boris and Matt! What a nice find! I'll put this with the adults in the guide. I'll see if it will mature so I can get a species ID. In fact, maybe our Eucnemid specialist can tell me from the larva. I'll ask.

… Jim McClarin, 9 January, 2007 - 3:28pm

rather beetle larva

Hi Jim,

I think it´s an Eucnemid larva - blunted tail is typical, and they also never have legs. Not many flies have a well developed head capsule.

regards, Boris

… Boris Büche, 9 January, 2007 - 9:26am

legs on larval Eucnemidae

I specialize in Eucnemidae. Over the years studiying Eucnemidae, especially larvae; I have come across eucnemid larvae possessing legs. Most notably, our fauna have quite a few primitive eucnemid species like Palaeoxenus and Schizophilus; both of which do have legs throughout the larval stages. Also, both of those species possess urogomphi, a trait very rare in Eucnemidae. Perothops and Anelastes are the other two primitive eucnemid genera whose larvae remain undescribed and in theory may possess legs throughout. The more advance species, especially in the Tribe Dirhagini will possess legs earlier the larval stages, but will lose them through subsequent molting and change shape in appearence. That phenomenon is call Hypermetamorphosis.

… Robert Otto, 15 March, 2007 - 1:57pm

Thank you, Robert.

It is a strange family. I can see why you would find them fascinating, worthy of devoting years of study to. I hope I someday encounter some of those other larval types.

… Jim McClarin, 16 March, 2007 - 5:46am

No problem, Jim

I love a good challenge. These beetles provide a great challenge to collect due to their secretive live. Spending a lot of time understanding their secret lives is worth it and could prove useful in sustainable forest management. Hopefully, in the foreseeable future, I will be investing in some photography equipment to post larval images of Eucnemidae on this site. I wish you the best of luck on your search for other larval types.

… Robert Otto, 16 March, 2007 - 1:41pm

That's great.

I think without bugguide as a resource I might still be sitting on these images thinking they were some sort of fly larva.

… Jim McClarin, 16 March, 2007 - 2:25pm

I agree

Definitely Eucnemidae. Check for mandibles that are divergent.

… Matt Bertone, 9 January, 2007 - 2:54pm

Diet

What do they eat with their divergent mandibles, do you know?

… Jim McClarin, 9 January, 2007 - 11:11pm

Eucnemid diet

Hi!

I do not know whether feeding was ever observed directly (difficult in larvae living within galleries) - but there can be no doubt that Eucnemid larvae are wood feeders. Their galleries are rather tiny (larvae, unlike buprestids, always stretched within them), but made in fairly hard wood sometimes.
Sounds funny - but when digestion is done in part prior to feeding (what I suppose to be the case), outwardly acting mandibles (with several spines on the exterior edge) might be really useful to rip fibers allowing the enzymes to pass . . .

cheers, Boris

… Boris Büche, 10 January, 2007 - 6:41am

eucnemid feeding

Friends!
There is really serious doubt about eucnemid feeding on wood. Studies have revealed nothing in the larval gut and they most likely use extraoral feeding and digest the fungus rather than the wood and then such the "juices" back in. The "pump" close to throat is well developed.
The great majority of the known larvae do not have movable mandibles and all but the very few (Melasis, Isorhipis, Hylochares, Nematodes) work practically no galleries at all.
s.
Jyrki Muona

… Muona, 27 March, 2007 - 8:48am

Yes, I've noticed there are no tunnels for some species.

It's like they were teleported inside the log and just stayed there and grew :-) In fact, I haven't seen how they could have enough room to pupate. Their muscles are very slow moving and I presume they do nothing very energetic in the confining space they occupy.

One question in my mind remains unanswered: Why, in three out of four species of larvae I've found, are the larvae doubled back in their burrows with the "tail" close to the head? I'm guessing that if they don't eat any solids, they might not excrete and might not have a functioning anus. If so, this doubled-back position would not pollute their food supply with feces. But why do it anyway? What advantage is gained by their bent-in-two position?

… Jim McClarin, 27 March, 2007 - 7:04pm

Here are the outward-pointing mandibular spines:

… Jim McClarin, 12 January, 2007 - 5:44am

Thanks again, Boris.

After posing my question I read about the external digestion in white-rot sapwood in American Beetles. This afternoon I returned to the dead aspen trunk section where I found this larva and collected at least 20 more, hoping at least one will grow to maturity. I collected chunks of the white-rot sapwood too for them to live in.

None of the newly collected were anywhere near even 10mm, leading me to suppose that my size guess of 20mm was way off. The largest, in fact, was only 7mm, which I have corrected this one's size to. (I probably figured it was so large because it was huge compared to the smallfry I was shooting in the same container.)

I noticed that most of the larvae were doubled back on themselves, reminding me of some small larvae I found over three years ago but was unable to get adequate images of with my equipment at the time. I suspect now that they were eucnemids because of their strange position in the soft sapwood. Here's an image showing this posture:

… Jim McClarin, 10 January, 2007 - 5:29pm