Metaxina ornata, Broun, 1909

Johnson, James B., Emberson, Rowan M. & Marris, John M. W., 2008, Biology ofMetaxina ornataBroun (Coleoptera: Metaxinidae), with Notes on Associated Beetle Taxa, The Coleopterists Bulletin 62 (2), pp. 215-219 : 215-219

Observations on Metaxina ornata biology

Two middle sections of the original branch (diameter 3–4 cm, lengths 18– 25 cm) were sequentially removed from the first rearing container for dissection on 12 October. Initial examination of the branch segments did not reveal any insect activity. Tapping the branch segments sharply on the bench top did not dislodge any insects. However, during the first ten minutes of more detailed external examination of each branch segment, five adult M. ornata emerged and walked on the surface of the branch segments. None of the beetles showed a tendency to fly and all were captured with forceps and placed in a killing vial. This indicates that adult M. ornata are active within the mass of sooty mold, concealed from view and difficult to dislodge by typical collecting methods.

In some areas the sooty mold layer was found to be up to 6 mm thick among the tests formed by the scale insects. This amount of sooty mold apparently suppressed the growth of moss and lichen that were common on branches with less sooty mold. Searching through the sooty mold did not reveal any M. ornata , but did reveal staphylinid adults, H. hystrix adults and larvae, T. hispidellus adults and larvae, and D. punctata larvae.

After removing the sooty mold, individual scale tests were popped from the branch segments using a stout scalpel blade. Many contained adult or immature scales. In tests with no scale or obvious scale remains we found six, late-instar larvae and one pupa of M. ornata . Most of the larvae and the pupa were found in areas with particularly abundant scales and sooty mold, e.g., where the branch forked. It is assumed that the larvae entered the scale test via the dorsal opening produced by the scale for exsertion of the wax tube used to secrete honeydew and exit of the scale progeny. This behaviour would correlate with the small, narrow head of M. ornata larvae. Some of the larvae had a pink background body color, similar to that of the scale insects. Others were white in life, but turned pink when boiled. M. ornata larvae did not score the wood below the test.

Half of the larvae and the pupa were immediately boiled and preserved in 70% ETOH. Remaining larvae were set up to attempt rearing in 1 dram glass vials. The M. ornata larvae were supplied with two or three scale tests and sooty mold for shelter. Larvae of T. hispidellus (the most abundant coleopteran) and scale insects were supplied to the M. ornata larvae. No larvae gave indication of consuming T. hispidellus larvae. Larvae were observed to consume scale insects, few molted and none pupated, but this is consistent with the report of Morales et al. (1988) which associated M. ornata larvae with scales. The remaining larvae were preserved on 19 November due to a lack of additional available food. Additional rearing attempts with larvae from later samples yielded similar results.