“We live in the east San Francisco Bay Area and while on a walk, my daughter and I caught sight of these little guys crawling in a gutter area with about 1-2”of runoff water in front of our neighborhood houses”, writes Chrissy in her submission regarding the segmented, brown, worm-like critter pictured below. “There are trees above a few spots, and upstream, no trees. They are about an inch in length and seemed to resemble caterpillars, but we’re a bit flatter. They’d walk around underwater and when resting, typically had one end up floating at the surface of the water. I’m attaching two photos as we are curious about what they are! We’re hoping they’re not leeches. Thanks so much!” Of the two photos, we included the clearest one, but unfortunately, it is still difficult to discern the smaller details of the critter’s physical characteristics from this photo. Not only is the resolution not the best, but it blends in so well with the environment that it is difficult to tell which parts belong to the worm and which parts do not.

For example, the long appendage-looking object near one end of its body could be exactly that, an appendage. Or it could just be some floating debris in the water. Assuming it is an appendage though, we thought this could be a hornworm. Hornworms belong to a family of moths known as sphinx moths or hawk moths, and they are distinguishable by the ‘horn’ that grows from the rear of their bodies. They vary in color depending on the species but there are indeed brown ones with similar markings and segmentation to the one in Chrissy’s picture. They are completely harmless to humans and pets, and are mostly concerned with finding honeysuckle plants to munch on. The adult moths are definitely a sight to behold, and some of the world’s biggest moth species belong to the sphinx moth family.

Now, what has us mystified about Chrissy’s discovery is that hornworms are not aquatic whatsoever, so the fact that she found them walking under water is puzzling. If they are hornworms, we would guess maybe they had fallen in and what was interpreted as them walking was actually them trying desperately to get out of the water. If they are not hornworms, then they might be some type of aquatic worm, but we would not know what they are in that case. What Chrissy can do is take a sample of this worm (in a box with some water and air holes) to her local county extension office, or to the nearest university with an entomology department, to have someone physically examine the creatures. They might have a better chance at coming up with something.

In conclusion, our best guess is that the creatures Chrissy found are hornworms, AKA hawk moth caterpillars or sphinx moth caterpillars. Given how well the critter in the photo blends in with its environment, and given the environment itself in which the creature was found, we are not entirely sure if this actually is a hornworm. We hope this helps nonetheless, and we wish Chrissy the best.

Summary

Article Name

Segmented Brown Worm in Gutter Looks Like a Hornworm

Description

"We live in the east San Francisco Bay Area and while on a walk, my daughter and I caught sight of these little guys crawling in a gutter area with about 1-2”of runoff water in front of our neighborhood houses", writes Chrissy in her submission regarding the segmented, brown, worm-like critter pictured below. "There are trees above a few spots, and upstream, no trees. They are about an inch in length and seemed to resemble caterpillars, but we’re a bit flatter. They’d walk around underwater and when resting, typically had one end up floating at the surface of the water. I’m attaching two photos as we are curious about what they are! We’re hoping they’re not leeches. Thanks so much!" Of the two photos, we included the clearest one, but unfortunately, it is still difficult to discern the smaller details of the critter's physical characteristics from this photo. Not only is the resolution not the best, but it blends in so well with the environment that it is difficult to tell which parts belong to the worm and which parts do not.

Author

Worm Researcher Anton