Insects and Spiders - Western Banded Glowworm
Zarhipis integripennis
I found out a lot about glowworms and millipedes when I found these two together. The insect on the upper left is a Western Banded Glowworm (Zarhipis integripennis) larva. Sometimes it's easy to think of larvae as just small, unremarkable wormy creatures. But thinking of a caterpillar as a butterfly larva makes it easier to think of other larvae as much more compex and diverse. And this larva is definitely remarkable. And yes, they do glow!
Glowworm larvae are specialized hunters of millipedes. According to the expert, Darwin Tiernann, here's how the process goes: "When a millipede comes to within proximity of a [Western Banded Glowworm] larva, the larva races alongside it, mounts it, and throws a body coil around the millipede's front end. It then pierces the millipede's neck membrane with its mouth parts, and effects an action that causes the millipede to become quickly immobilized. The larva then burrows underground beside the millipede, only to emerge after a time to commence feeding. It consumes the soft insides of the millipede only, predigesting the millipede's tissues with its own enteric fluids, which it apparently regurgitates while feeding. Only the millipede's skeletal parts remain uneaten after the meal."
Okay, then! Now I know why I found these two together.
To find out more about millipedes, click here.
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I tried to get the glowworm picked up on a leaf, but that didn't work, so I just picked it up. The glowworm excreted a lot of some kind of liquid. Later I found out that, "When handled, [the glowworm] secretes a clear amber fluid from U-shaped pores on abdominal segments 2-9." Here the liquid is light yellow, but it turned darker quickly. See photo 9 below.
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Notice the eye-shaped openings on the sides of the larva's segments. These are spiracles, which can be opened to allow oxygen in, and closed to prevent the insect from losing too much moisture.
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After just a minute or two, it decided it was fine with crawling around on my hand.
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That "clear amber fluid" left quite a mess!
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This is a photo of the glowworm in the beetle stage. Totally cool antennae, right? Only the males progress to become beetles. When the females become adults they are said to be "larviform" and not "larva." That means they still look like larva but have specific differences that are not obvious to the 'naked eye'. One of the differences is that the adult females have an ooporus that enables them to lay eggs. The females attract males with pheromones, and the males' antennae with their loads of surface area are really great at detecting even minute traces of the pheromones. I took this photo at Solano Land Trust's Lynch Canyon, May 2012.
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