All Aboard the Railroad Worms!

A railroad “worm,” courtesy of Andy Reago & Chrissy McClarren on Flickr

Railroad worms are not actually worms. Despite their appearance, they’re not caterpillars, either. Most of them are beetle larvae, but some of the aren’t – we’ll get back to that in a minute.

Also known as “glowworms,” railroad worms are named for the bioluminescent sections on the sides of their bodies look like train car windows when they light up at night. How cute! They’re little arthropod trains; someone needs to make them into transportation for tiny forest dwellers in a fantasy novel or something.

Apart from the “windows,” railroad worms can also make their heads glow red, which is thought to help them see better at night and scare off predators. Both the yellow and red lights are created using luciferin and luciferase, the same molecules and enzymes fireflies use to make their lower abdomens glow.

As cute as their name is, we really ought to call them “railroad larvae,” because most railroad worms are actually larvae of beetles in the Phrixothrix genus of the family Phengodidae. However, female railroad worms never metamorphose into beetles and retain their larval features throughout their lives, so you could run into some Phrixothrix “larvae” that aren’t actually larvae at all! When railroad worm males grow up, however, they trade their glowing windows for a sick pair of feathery antlers, I mean, antennae:

An adult male Phrixothrix beetle, courtesy of the USGS Bee Inventory and Monitoring Lab – all in favor of renaming these dudes “reindeer beetles” say aye!

The best time to find a railroad worm is at night or after a rainstorm when they come out to hunt for food. During the day, these colorful, shimmering insects typically spend their time snoozing in the dirt or hanging out on tree trunks, if you’re searching for railroad worms in a lazier mood.

It can also be easy to mistake railroad worms for colorful millipedes in the daylight. Unlike millipedes, however, railroad worms are insects and only have six legs as compared to a millipede’s hundreds – in fact, they actually eat millipedes! Railroad worms also eat a ton of other garden pests, too, so it’s always a good sign to see one crawling around your tomato plants.

…Why does everyone have tomato plants? Why do we always talk about tomato plants when we talk about home gardens? We never talk about blueberries or squash or cabbage…

Well, all that to say that it’s a good sign when you see railroad worms around your zucchini and boysenberries, too.

2 Comments on “All Aboard the Railroad Worms!

  1. Point taken…we do love tomatoes……BUT…..James and I picked 200 ears of corn in a friend’s garden Saturday….we just creamed and froze 100 of them. The plants were tall and the field was super clean….it was fun. You can get lost in a cornfield… And our zucchini and squash plants are huge and beautiful with large yellow blossoms under the leaves…we grated and froze zucchini tonight to use in chocolate cake and zucchini bread this winter. We have been eating squash alost daily….dresh is best! Those plants are dramatic…should be as valued as tomatoes….but you know….a summer homegrown tomato is the best!

    But….we have never seen a railroad worm….that is a new one to me.

    Liked by 1 person

    • That sounds great!! I love fresh squash, it’s hard to beat. I’ve never seen a railroad worm either, but I’m definitely going to be on the lookout for them now πŸ˜„πŸš‚πŸ›


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