Unusual view of Harlequin ladybird pre-pupa

[Bruce Williams]

Stony Stratford, Bucks.

I thought some of our members might find this interesting:

As I mentioned in a previous post, at the present time there are many hundreds of Harlequin larvae, pre-pupae and pupae along a short stretch of the Great Ouse in Stony Stratford. I spent about 90 minutes checking them out today, accompanied by a very bored (but understanding) dog. Saw several things of interest but was particularly surprised to find this pre-pupa holding this upright position (see pic).

When a small insect crawls over a pre-pupa or pupa it almost always reacts by flicking upwards one or more times - I assume with the purpose of dislodging or scaring off the offending insect. Pupae sometimes remain upright for some time however pre-pupae almost always quickly return to their normal resting position. In fact this is the only ladybird pre-pupa I've seen holding this pose.

I took several shots as not only is it a very unusual pose, it was also a great opportunity to get some shots of the underside of a Harlequin ladybird larva. The yellow belly suggested to me that it was about to pupate so I waited around as long as I could in the hope of observing and getting some shots of this process - but no luck and time ran out and I had to leave.

Anyway, here's the pic:



Bruce

[Bruce Williams]

...bit of an update on this post.

This morning I brought home three Harlequin ladybird pre-pupae (still attached to their stinging nettle leaves) and set them up side by side with the intention of shooting a photographic series covering the process of pupation.

There are very few clues to alert you to when pupation is going to start which means you have to keep a close eye on them over several hours. The first stage of pupation takes only a couple of minutes and involves the skin splitting and rolling back to form a pad at the base of the pupa (see Gallery pic of Harlequin pupa) so if you're away for more than a few minutes you can easily miss this process.

Anyway, relating back to the original post:

The three pre-pupae were initially in the shade and for all that time they stayed in the normal head down position, just pulsing rhythmical from time to time. After watching for a couple of hours I moved them to the patio table (which was in full sun) so I could better enjoy a beer while I was waiting. Within about 5 minutes two of them had risen up into the same position as my original photo. I then lifted a plant container up onto the patio table to give them shade. Withinin a few minutes they had returned to the normal head down position. I removed the container so they were in full sun again. Within a few minutes they lifted up again - so I replaced the container and they returned to head down. I left them in shade for the rest of the afternoon.

So my guess is that the leaves got very hot in the sun (it was very sunny) and the pupae lifted up to minimise the area of their body in contact with the warm leaf - simple temperature control.

Just my thoughts of course .

Bruce

[Paul mabbott]

Nice observation, Bruce. You could well be right in your deduction.

[Bruce Williams]

Thanks Paul.

I carried out some more simple tests with both pre-pupae and pupae. I currently have 4 pupae and 3 pre-pupae (Harlequin) on a container grown patio rose. Moving the container in and out of direct sunlight produced the same result.

Out of interest, I managed to shoot pupation series on two of the pre-pupae under observation yesterday. The third pupated this morning before I got up .

Bruce