Sunday, May 17, 2015

The secret world of the Cardinal Beetle larva revealed...

I think it was back in February of 2014 that I found a number of cardinal beetle larva in local woodland. In this particular spot there are several fallen trees and on one of them, the bark is now flaking off. Besides hundreds of woodlice and a few darkling beetles, there were these yellow larvae. 

I thought it would be interesting to try and observe the metamorphosis into pupa and then adult beetle and so took a couple home with me. I set up a suitable habitat inside and old fish tank and provided them with some of the bark from the tree I found them on. Then it was a case of just checking every now and then for any change once spring began to arrive and hoping that I didn't miss it. Of course I had no idea whether it would happen that year as I knew that these beetles can spend up to 3 years as larvae.

The Cardinal beetle larva
Spring 2014 came and went with no signs of either one being about to pupate. I was going to have to be patient and let them spend another winter with me. From the 1st of April 2015 I began the task of checking again, whenever I remembered to do so.
I didn't see anything happening until the 23rd of April. I hadn't checked them the previous day, but had on the 21st and so I assume that one of the larvae had begun to change sometime on the 22nd as it seemed too advanced already to have happened overnight...





How amazing that you can already see the eyes, antennae and legs beginning to form.
By 7pm on the same day you could clearly see the features had become more defined and could now also see the wing buds... 



A closer look revealed details of the mandibles and maxillary palps. The mandibles are a pair of hard, tooth-like structures that move horizontally to grasp, cut and crush food. The maxillary palps are two pairs of finger-like appendages found around the mouth in most beetles. The are used to move food into the mouth and are the maxillary and labial palps...




A view from above


I rotated this picture for a better view of the developing face



In profile

The next time I checked on the larva was at 11.35pm on the 25th of April and as you can see, there had been quite a change in colour and the features are becoming even more defined. I assume those nasty looking spikes it now has are a defense against predators?



The following morning, yet more changes with those dark patches now showing on the abdomen segments...




A closer look

You have to wonder about how aware the insect is at the stage, if at all! It would certainly wriggle around if disturbed...









This next photo was taken at 5.30pm on the 27th of April...




The next opportunity I got to check was at 7.15am on the 28th of April. And there it was; the adult beetle had emerged. Still looking very teneral but I could now see what I had suspected from the colour changes, that this was a Black-headed Cardinal Beetle ~ Pyrochroa coccinea.








You can clearly see the empty pupal case beside the beetle in this next picture...









By 6.30pm on the same day the beetle had coloured up and was becoming quite mobile...






I decided to keep the adult beetle one last night to ensure it was fully fit for release and the next morning, the 29th of April, bright and early, I returned to the exact spot where I found it and set it down on the very same fallen tree...



It was a beautiful, perfect spring morning...
This is the glade, who wouldn't want to live here?


The fallen tree where I found and released the beetle

Finally a little video of it scampering off to start its new life...

(You will need to view this online, it won't appear in the e.mail version)

video


What an amazing thing to be able to witness. I gained so much knowledge too of just what does happen and the timescale involved. It had taken one week from start to end and I had been fascinated by the whole thing. What a privilege and to be able to then release a perfect cardinal beetle to the exact same spot with no harm done was mission achieved for me.

The second larva had shown no signs of emerging this year at all and as it was still alive and well, I decided to return it too. I found a suitable piece of loose bark that I could lift just enough to place the larva under and then carefully let the bark settle back.

That's all for this update, I hope you found it as interesting as I did, or at least got some idea from my photographs of what goes on in the secretive world of the cardinal beetle larva.

Until the next time...

4 comments:

  1. Great photos JJ. Disgusting but equally fascinating larva and a lot more pretty once a beetle lol. I must agree too, who wouldn't want to live in that beautiful glade.

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    1. Thanks Ian. Yeah I guess it's a face only a mother could love eh ;-) The little glade is quite a special place though...

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  2. Utterly fascinating! What a great experience. I know nothing about beetle larvae and their metamorphosis so thanks for this research and sharing your fantastic photos with us. And what a place to live...... :-)

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    1. Thank-you Mandy. I really enjoyed the experience and getting to share here is a bonus. That little area is a real favourite haunt of mine and it's easy to see why...

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