New skins, new attitudes




Overnight, the majority of the caterpillars changed their skins. They spin a pad of silk, and then hook their rear feet in the silk; then they wiggle and shimmy their way out of the old skin. This is an old skin. You can see the rear feet at the top left, and you can see some of the hairs from the old skin in the middle of the shot. Click on the picture for the bigger version.



Here, you can see a first-instar caterpillar (left) who’s a day or so behind the game. The difference in size between the first instar and second instar head casings is substantial.



When they come out of the day of rest with new skins, they have a voracious appetite; they turn the mulberry leaves into lace.



It’s hard to get the focus just right to see it, but the head casings are surprisingly hairy.


Too much sausage, not enough casing.



After five days, the silkworms have grown SO much! Their heads are the same size as they were before, but now the heads look tiny on their thick bodies. The bodies look like they’re over-stuffed – like too much sausage stuffed into not enough casing.



At this scale, the head is about the same size as the other one. See how much it’s grown?



This one looks like it’s getting ready to shed its skin. This process involves a day of rest, followed by shedding the face mask and the full skin for a larger, looser one.

For I will consider my moth Jeoffry.


This is a male Polyphemus moth. I’m always fascinated by the variety of scales and textures on their wings, and I got some close-up photos so you can really see why butterflies and moths are called “Lepidoptera” meaning “Scaled wings”



The scales are formed of chitin, like the exoskeleton and the substrate of the wing, and they provide insulation, aerodynamic effect, and coloration. The colors can help a moth hide, or help it protect itself.



The thick, furry scales on the moth’s body not only help it retain heat (produced by the muscles – they can actually fly at quite low temperatures, and the body is hot to the touch after flight) but they also help make the moth harder to bite – the scales come off, and you might just get a mouth full of fuzz.



The gray fur on the head reminds me of salt and pepper hair.



These eyespots mimic the eyes of a predator. The moth will often rest with its wings folded, so that the spots are concealed – and then pop them out if threatened. This mimicing of a predator (particularly a predator common to the prey species and its predator species) is common in the animal world, and is called Batesian mimicry. I’ve gotten to observe it in Polyphemus moths first hand. After they are done breeding, I often feed spent moths to our backyard chickens. One female proved that she wasn’t quite done for, when the chickens ran up to claim their tasty snack – she popped out those big black eyes, and the chickens literally backed… away… slowly. It was cool, and kind of creepy.


Here you can see the texture of the individual scales. If you click on the picture, it takes you to the full-size image, where you can see it REALLY close up. The shiny spot is wing with no scales at all – it reflects light, and light passes through it, like glass.



The legs have another kind of hair-like scale. The big, muscular thighs and knees remind me of tarantula legs.



Because Jeoffry is a male moth, he has huge, plumose (feathery) antennae. The males use these to detect pheromones, or sex hormones, released into the air by the female. They can fly miles to find a female, tacking into the breeze to follow the trace of scent.



Here, in really-really-close zoom, you can see the individual little hair-like scales on the antennae; these have scent receptors which will comb through the night air and allow Jeoffry to smell his potential mate.

So many hairy babies….


They hatched out just a couple of days ago, but they’re already noticeably larger. They will grow until their skins can’t expand any further, and then shed. On the bottom right corner, you can see the silk strands that they lay down constantly – these function as a safety line, if one of them falls off a branch.

Am I blue…. ?


These silkworm eggs are starting to turn “blue” – the developing worm inside separates from the shell, and they get a hazy lighter color. About half the eggs in this photo are blue – the others are likely nonviable.


If you look really close, and you’ve got a good magnification on your camera or hand lens, you can see the caterpillar curled inside the egg.



These have reached the head pigmentation stage; you can see the little dark heads. They’ll hatch within another day or two.


Calleta hatchlings

The Calleta caterpillars (Eupackardia calleta) started hatching today. These beautiful moths are native to much of the American southwest. I am raising them mostly for the fun of it – they do produce silk, but it’s not one I’ve made into yarn yet.


This tiny hatchling is eating cenizo – Leucophyllum frutescens – which many of my gardening friends call purple sage. Not related to the Salvia sages at all.

The caterpillars are covered with tiny bristles called scoli; these aren’t spiky to the touch for a person, but they would be get in the way if you were, say, a spider trying to put the bite on a caterpillar.



The insides of the hatched eggshells are beautiful – like rosy opals. The colors remind me of Maxfield Parrish.


Silkworm Season is beginning!

Every year it happens… the leaves pop out on the local mulberry trees, and then it’s time to start the silkworms.

10153303_10207606446412881_4991094600487356790_nThe Ancient Wisdom version says that you should start the silkworm eggs when the leaves are the size of a mouse’s ear. We don’t have the kind of long, slow spring where that lasts for long – so by the time I get a chance to snap a picture, they’re almost the size of a dime. This is a feral white mulberry tree in my yard in south Dallas.


These are the eggs. You can tell from the size of the fibers in the torn paper towel edges, these are pretty tiny. They’re about the size of poppy seeds.


When you get really, really close up, you can see the texture of the egg shell. The forming caterpillar embryos inside are in a state of rest called diapause; it allows them to survive through winter temperatures without dying, and they begin to metabolize and develop once they warm up in the spring.