A railroad worm is a

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

or larviform female adult of a

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

of the genus ''Phrixothrix'' in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Phengodidae, characterized by the possession of two different colors of

bioluminescence Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorgani ...

. It has the appearance of a

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder ...

. The eleven pairs of luminescent organs on their second thoracic segment through their ninth abdominal segment can glow yellowish-green, while the pair on their head can glow red; this is due to different luciferases in their bodies, as the reaction substrate, called luciferin, is the same. The "railroad worm" name arises because these glowing spots along the body resemble the windows of train cars internally illuminated in the night. The light emissions are believed to be a warning signal to nocturnal predators of their unpalatability or a defense function as they can suddenly be turned on, spooking predators with a sudden flash. When handled, the larva may eject a possibly distasteful and corrosive reddish liquid. The term "railroad worm" is also sometimes applied to the apple maggot.

References

External links

* Phengodidae Bioluminescent insects {{elateroidea-stub