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SHIP TIMBER BEETLES

LYMEXYLOIDEA

T

he superfamily Lymexyloidea is represented

today by only a single family, Lymexylidae.

The world fauna includes only a few genera and

species, and these are often rare. Evidence shows

that they were more common in the geological

past, with a number of fossils known from

Cretaceous amber, 100 to 120 million years old.

The beetles are wood borers, particularly

associated with standing dead wood such as

lightning-struck trees. This has earned them the

name of ship timber beetles, as the masts of old

wooden sailing ships are effectively standing dead

trees from a beetle’s point of view. They can be

pests, because they bore directly into the heartwood,

damaging the strength of the timber, a particular

problem in the days of sailing ships when infested

weakened masts could snap off in a gale.

The female beetle bores a cylindrical tunnel

directly into the wood at right angles to the trunk,

and there she lays the eggs. Each egg is coated with

fungal spores which the female deliberately carries

in special pouches called “mycangia.” These spores

are then “farmed” by the hatching larvae in their

own branching tunnels. The fungus, often unique

to a species of beetle, thrives in the dark humid

network of holes, which are kept open by the

beetles to ensure a supply of oxygen. This is an

example of symbiosis, where the two organisms,

the beetle and the fungus, are mutually dependent.

The fungus is carried by the beetles from tree to

tree and cultivated in their tunnels, where it

provides a source of food for the larvae.

LYMEXYLOIDEA—Ship Timber Beetles

superfamily

Lymexyloidea

known species

70

distribution

All continents except Antarctica, but

generally rare. One or two species are

common in tropical Africa

habitat

Forests, from northern conifer forests to

tropical rainforests. Larvae usually develop

in dry, dead trunks

size

10–50 mm

diet

Larvae feed on symbiotic fungi inoculated

into tunnels in wood by the female. Adult

feeding is not known, and possibly many

species do not eat as adults

left | Lymexylon navale The name

refers to the navy and the former

association with ships’ masts. This

is now a rare species in Europe and

western Asia.