What's in the box? No.5 - a shiny jewel and some uninvited guests.

My wife is beginning to recognise the signs. A jiffy-bag lands on the doormat and there's a small box or tube inside it - yup, a specimen has arrived in the post. This time it was expected as the collector had emailed in advance to ask if I wanted a specimen or two of the colourful Rosemary Beetle Chrysolina americana (Chrysomelidae) which he had found on Hydrangea plants in a garden centre in Gloucestershire. Hydrangea is not the usual host plant - it is generally found on rosemary, lavender, sage or thyme. Of the two specimens sent, one was still alive before being sent and arrived here still very active - it is now in a pot with some sage leaves while the other has been investigated for your reading pleasure...

Dorsal view of C. americana showing the colourful stripes and double rows of punctures. Length approx 7.5mm.

The area around the suture (where the wing-cases meet) showing punctures plus some fine sculpturing.

Ventral view.

The dorsal views show what a pretty beast this is - metallic stripes on a blue background. However, the ventral view shows something less welcome in the form of numerous white tufts.

Threads of mould, plus some larger lumps, growing on the underside of the beetle.

Mould growing underneath the wing-cases which have been spread apart. The triangular structure at the top is the scutellum.

This highlights a major problem with maintaining an insect collection - the avoidance of pests which can damage specimens. With a relatively large 'meaty' beetle like this, it is important to prepare specimens to prevent mould - for example they can be dried and some people add cloves to the drying chamber to help avoid fungal growth. The next step was to see how bad the damage was.

Dorsal view with wing-cases spread.

Although the focus isn't too clear, the abdomen can be seen to be hollow with the upper surface missing and with mould coating the inside. There may have been other invertebrates feeding on the beetle as well as fungal attack.

Looking closely at the underside of the head, as well as mould, a white oval egg can be seen in the centre, below the antenna.

So, there has been some invertebrate activity - this egg was just one of several so as you'd expect, I took a closer look...

One of the eggs (mag x400) showing some small bumps on the surface. The linear structures top right are fragments of fungal hyphae from the mould.

Searching the beetle more carefully, I eventually found something that could be responsible for the eggs - a hairy mite which I think is Glycyphagus domesticus (the Furniture Mite).The pale colour and long hairs are characteristic - it used to be associated with old damp furnishings where it fed on fungi that grew on stuffing etc. So, when the moist, freshly dead beetle began growing mould, it is likely that this mite arrived to feed on the fungus.

The mite (possibly G. domesticus) on the beetle.

Of course, I don't know for certain that the eggs come from this mite. However, with the specimen in no condition for adding to a collection, I've put it in a container to see if the eggs hatch and if so, what emerges. In the end, this is a tale about the importance of preparation and maintenance of insect specimens more than my usual bug-nerding. A web search for 'dermestes' or 'museum beetle' will provide you with many unhappy tales of entomological destruction. However I don't need to repeat these so, given that I have a microscope and a camera, I thought I'd finish with a couple of shots of fine morphological detail...

The inner surface of a wing-case showing the lack of metallic colour, but with the rows of punctures clearly visible.

One of the beetle's 'feet' showing tarsal segments bearing a sickle-shaped claw and a dense brush/pad of yellow hairs. There are also other hairs and some longer, sparser bristles.