Enjoying some down time on the patio we noticed a beautiful orange hairy caterpillar on one of the chairs. Avid watchers of Miniscule will know how caterpillars get around and the sucking and slurping sound their feet make. Our ginger beauty moved about the chair like Michael Jackson in moon walk mode, only in reverse. Somehow it moved about in one fluid motion from which I deduced it was not related to the Minuscule caterpillar. So I Googled How do caterpillars walk? and here’s how a real caterpillar walks.
Caterpillars walk by lifting and compressing the body between the last two pairs of legs, then moving the last pair of legs forward a bit, then they lift the next segment and move the penultimate pair of legs forward, then the next pair , and so on. There is a considerable distance between the last pair of true legs and the first pair of prolegs, so that that step in the sequence is usually longer, giving Caterpillars more mobility than might be imagined, especially if some pairs of prolegs are not present, as in some members of the families.
What is the difference between true legs and prolegs, I hear someone ask. This is what I found:
Caterpillars of different families have different numbers of legs. The number of legs is a constant throughout its life, depending only on the species. All Caterpillars have 3 pairs of true legs attached under the thorax. The true legs are segmented, with joints like our knees and ankles. They have a little claw on the end. Most caterpillars also have up to five pairs of prolegs. The prolegs are not segmented, but are cylindrical. They are used for walking and clinging, as they have a set of microscopic hooks on the base (crochets). The last pair of prolegs on the anal abdominal segment are usually called claspers.
Interesting, huh! Then I wondered whether caterpillars have sex? With that long fur and all those legs it wouldn’t be easy, would it? As it happens no need for concern about the intricacies of caterpillar coital capers because …
Caterpillars are the immature forms of their species, like children in our species. Only the adult moths and butterflies can have sex. However: the developing sexual organs may be seen through the transparent skin of some caterpillar species, typically as a pair of yellow organs, one each side of the dark dorsal heart line.
Phew! That’s a relief. So what about eyes? How many eyes do caterpillars have? The caterpillar in Minuscule has two so I was surprised to learn that …
Most Caterpillars have six very simple eyes on each side of the head (making 12 in all), although some species have five or seven each side. These light sensitive stuctures are called ocelli or stemmata. These probably only sense light and dark, and do not distinguish shapes or colour.
Hmm, my caterpillar is definitely not of the Miniscule genre. Never mind, he’s still beautiful. But wait, is he a he, or perhaps a she?
While I didn’t find any information about the sex of caterpillars I did find these ways to tell a male from a female butterfly or moth …
- Sex brands – like product branding only prettier
- Size – the lady caterpillar is fatter (such an ugly word) because her undercarriage serves as a transport carrier for her precious cargo of eggs
- Flightless females – in some families the females have no wings
- Dimorphism – different patterns between male and female of the species
- Territorial behaviour – while he flies in continuous circles around his territory, she, poor darling … ‘wanders haphazardly across the land’ (done a bit of that in my time)
- Abdomen tip – female of the family has pheromone dispersing glands covered with a tuft of hairs; the male can emit pheromones in some families but his tufty mound is less pronounced
- Dissection – eeww! Some species have no observable sex identifiers forcing us to cut the caterpillar abdomen open to locate the genitalia. Makes you grateful humans are easily spotted for their girly or boysey bits.
Thank you to the Butterfly House for the continuation of my learning about all creatures great and small.
If you have recently made a fresh pot of coffee, why not pour a second cup and enjoy the Miniscule clip. It’s five minutes of very clever artfulness called Two Caterpillars