|Megatoma undata (Linnaeus, 1758) Notable B|
|Megatoma is a 'wild' dermestid ie not synanthropic, and is of widespread
occurence across southern England and the midlands, there are also records from the north, Wales and Scotland.
Adults are occasionally found indoors (Hinton, 1945)
and Fowler recorded them on skins and furs but in his very thorough monograph Hinton states that he was unable to
find any other records which associate Megatoma with stored products. The typical habitat of the adults is
around dead wood although they may also be found on flowers eg Crataegus or Malus in the spring and
early summer when they may be pollen feeders. In general they are probably more typically dermestid in feeding habits; they
have been observed feeding on cast aphid skins and dead fleas (Peacock).
As pointed out by Peacock the distinctive markings may be cryptic against lichen covered bark and there is a
superficial resemblance to the Zebra spider, commonly seen locally in hot weather, with which Megatoma is often
found. Larvae have been recorded feeding on dead insects in spiders' webs and developing in the nests of a range of
Hymenoptera including the locally common Hornet, within various insect bark burrows including Molorchus,
Anaglyptus and Tetropium and under the bark of a
wide range of deciduous trees. Adults and larvae may occur together and adults generally occur from April to June
although they may be found year round under bark.
During April and early May 2008 a colony of adults was active an a bare, ie devoid of bark, Fagus stump in Cassiobury park. During hot sunshine they became active on the shaded side of the stump, usually 3 or 4 present at any time and generally among and ignored by, numbers of the ant Lasius brunneus. Males were seen to roam on the surface of the wood or to take short flights, always alighting in the same area. Females mostly remained in the entrances to old Tillus burrows, the head and pronotum exposed, here they spent time enlarging the entrance by nibbling away at the wood, and after a while these enlarged burrows became obvious and were seen all over the stump. On a single occasion a pair were seen mating within one of these holes, the female now facing into the burrow. Despite daily observation no adults were seen beyond the first week of May. During these few weeks when Megatoma was known to be active many other similar habitats were examined both in the park and through Whippendell wood and our routine of searching under bark and extracting from samples continued as usual but no other specimens were seen.
3.6-6mm. Elongate and entirely black but for eyes and tarsi which are brown. Entire upper surface with dense and dark backwardly recumbent scale-like pubescence which is clearly visible in outline. Head deflexed, with large prominent eyes and a very prominent median ocellus. Densely punctured throughout, in female a little finer and closer so that the head appears dull. Antennae 11 segmented, 3-5 quadrate, placed on front of head before eyes, dimorphic; club in male much larger. Pronotum highly arched and broadly explanate towards hind margin, less so in female, contours smooth ie without carina or fovea. Margins roundly narrowed to obtuse front angles which are visible only from the side, hind angles strongly sinuate. Puncturation discreet, a little larger than on head, especially in female. Scutellum punctured as elytra, a little wider in male. Elytra elongate and very convex, sinuate at base and matching basal curve of pronotum, strongly sinuate laterally at level of hind margin of metasternum. Pronotum and elytra with characteristic pattern of pale, scale-like pubescence. Legs pubescent; tibiae with very small terminal spine otherwise smooth. Tarsi 5-5-5, segment 1 of hind tarsi longer than 2.