Byrrhoidea such as Heteroceridae, Limnichidae,

and Dryopidae, which between them may

comprise a large proportion of a light-trap catch

in the wet tropics. The adult dispersal flights makes

these beetles very mobile; some Heteroceridae

species can be found over the length of Africa.

The largest Byrrhoidea are Eulichadidae (forest

stream beetles) and Callirhipidae (cedar beetles).

Eulichadidae have aquatic larvae and terrestrial

adults that resemble a large click beetle. All species

except one belong to the genus Eulichas and are

found in tropical Asia, but Stenocolus scutellaris is

The riffle beetle Peloriolus brunneus (Elmidae)

is known from only two specimens, apparently

collected by a young Charles Darwin in 1836

on the return voyage of HMS Beagle, on the

Atlantic island of St Helena. The species has

never been collected again, despite extensive

surveying of St Helena, leading to discussion

of whether it is extinct or whether it was

mislabeled. It was possibly collected in South

Africa, the Beagle’s previous stop, but it has

never been found again there either

above | Callirhipis (Callirhipidae) From

Singapore, this beetle shows the scent-detecting

flaps of the male antennae, which can detect

females over great distances.

found in California, USA, which is a strange

biogeographical distribution. The Callirhipidae,

which have hugely developed antennal scent-

detecting flaps in the male, are more widespread,

and their larvae develop in dead wood. Callirhipis

philiberti, from the Seychelles, has been reported

alive in driftwood on the coast of Kenya, after

traveling 1,000 miles (1,600 km) by sea.

right | Sostea (Dryopidae) From tropical Southeast

Asia. Members of this genus are among the only

long-toed water beetles with a colored metallic sheen.