A railroad worm is a

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

larviform Larviform female is a biological phenomenon occurring in some insect species, where the females in the adult stage of metamorphosis resemble the larvae to various degrees, while the male appears more morphologically adult (as imagoes). The resemblan ...

female adult of a

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

of the genus ''Phrixothrix'' in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Phengodidae The beetle family Phengodidae is known also as glowworm beetles, whose larvae are known as glowworms. The females and larvae have bioluminescence, bioluminescent organs. They occur throughout the New World from extreme southern Canada to Chile. ...

, characterized by the possession of two different colors of

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

. 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 Sym ...

. 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

luciferase Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words ''luciferin'' and ''luciferase'', ...

s 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. The term "railroad worm" is also sometimes applied to the

apple maggot The apple maggot (''Rhagoletis pomonella''), also known as the railroad worm (but distinct from the '' Phrixothrix'' beetle larva, also called railroad worm), is a species of fruit fly, and a pest of several types of fruits, especially apples. ...

References

External links

* Phengodidae Bioluminescent insects {{elateroidea-stub