Showing posts with label pupa. Show all posts
Showing posts with label pupa. Show all posts

Saturday, March 25, 2017

Leggy Bugs—Caterpillars (Lepidopteran Larvae, which Become Butterflies and Moths)

Butterfly and moth caterpillars have fewer legs than the leggy bugs I wrote about last month (“Leggy Bugs--Centipedes and Millipedes”).

One nice image I found was helpful with identifiers. View a nicely captured example of movement at "Close-up Caterpillar Footage".

My image shows a caterpillar with two possible paths to adulthood of butterfly or moth. The pupa stage is chrysalis or cocoon. A butterfly emerges from a chrysalis, and a moth emerges from a cocoon. Their antennae and body shapes differ. Butterflies are active in the daytime, while moths are active at night.

North Carolina State University's "Lepidoptera" site succinctly describes the order that butterflies and moths belong to:
The name Lepidoptera, derived from the Greek words "lepido" for scale and "ptera" for wings, refers to the flattened hairs (scales) that cover the body and wings of most adults.”
The site includes basic information about the caterpillar life cycle and the adult stages as butterflies and moths. It also discusses animal classification terminology, noting that Lepidoptera is a category (order) under Insecta (class). It also summarizes subcategories (families) of lepidoptera. One family, Geometridae, includes inchworms. (Their locomotion is so weird to me that I'm going to save writing about them in my next article.)

I’ve always wondered about caterpillars having many legs, yet emerging as butterflies or moths after complete metamorphosis, with only six legs. For differentiation between complete (four-stage) and incomplete (three-stage) insect metamorphosis, visit the Pacific Science Center Exhibits “Metamorphosis” site.

Another curiosity for me is that “caterpillar” is their larval term, whether they emerge as either of the flying insects. Swithzoo’s "Caterpillar" site explains: “The caterpillar's six front legs transform into the adult insect's legs, the other 'prolegs' disappear, wings grow, and the insect emerges as a beautiful moth or butterfly.”

Purdue’s “Is It a Moth or Is It a Butterfly?” elaborates on the caterpillar’s prolegs and other characteristics:
Caterpillars have a well-developed head and a cylindrical body, which is made up of 13 segments. Each of the three segments behind the head has a pair of legs, just like adult insects. But caterpillars also have some additional, fleshy, leg-like appendages - called prolegs - on other segments. Prolegs have tiny hooks at the end that function to grasp things such as the stems and leaves of plants.
The Library of Congress site “How can you tell the difference between a butterfly and a moth?” provides loads of helpful, short, section titles about these insects (wings, anatomy, behavior, cocoon/chrysalis, …).

Backyard Nature's site "Caterpillars” shows an image that indicates the site’s focus on these animals’ voraciousness—webpage title imaged as leaves chewed into contours of “CATERPILLARS”. Visit for close looks and reads about these leggy bugs.

More resources:
  • GardeneGateeNotes “Cocoon versus chrysalis
    This site shows a cocoon and chrysalis side by side and provides a short, nuts and bolts explanation.
  • Diffen's "Butterfly vs. Moth"
    This site has a handy two-column table at the top, then more details and images. This site also includes a Related Comparisons section with links to pages comparing other related insects, other similar animals.
  • Easy Science for Kids "Butterflies and Moths"
    A table near the top shows differences between moths and butterflies, followed by basic text and a diagram (parts identified) for those who are just starting to look into these flighty insects.
  • Brittanica Kids site
    The main attraction is a helpful diagram of a butterfly and moth side-by-side and corresponding parts identifiers.
  • Kids' Inquiry of Diverse Species site for “Butterflies and moths
    This site’s format is question-and-answer, with basic and elementary approach.
  • Moths vs Butterflies
    Entertaining video (mostly narration) of basic contrasts between these flyers.

Leggy Bugs articles:

Sunday, July 31, 2016

Closeup of Molted Cicada Exoskeleton (and More Info)

Earlier this week, I spotted a sizable empty shell of a bug, maybe a beetle, I thought. It was about an inch tall, stuck to a corner of a porch column, seemingly hugging it, about three feet above the porch. It looked like all the innards might have been cleanly sucked out, maybe consumed by parasitic larvae, leaving only exoskeleton and maybe other chitin.

For a larger, unreduced image, click here.

Not being an entomologist or gardener who might know about bugs, I wondered how to get information about the shell's former occupant and how it departed. A Google image search yielded seemingly countless, overwhelming results.

I decided to turn to LinkedIn connections, and posted a pic and update, hoping to get someone to identify the item. I was in luck! Two people, John Rothgeb, and Steven Schwartzman, replied with great leadoff info.

From John, a declaration and web link: "Looks like cicadas or even a Giant cicada - http://texasento.net/Cicada.htm". The website images and first .wav file sent me off to Googling more info.

From Steve, a strongly specific term and also two links to blog articles he had written about cicadas himself:
The thing in your picture appears to be the exuviae of a cicada. That word is a Latin plural that entomologists use for the exoskeleton that an insect casts off as it grows from one stage into the next.

Here are a couple of instances from my blog:
https://portraitsofwildflowers.wordpress.com/2014/07/22/exuviae-2/
https://portraitsofwildflowers.wordpress.com/2011/07/18/exuviae/
A third LinkedIn connection declared the shell to be cicada. (Happily, LinkedIn networking can be fruitful for topics besides work, careers, and occupations. (My LinkedIn home page shows more number of views for the exoskeleton picture and inquiry than any other topic I've announced in recent memory.)

Besides increasing my curiosity about the animal, the terminology I was encountering sent me hunting down definitions and pronunciations for chitin and exuviae. Interestingly, the first "c" in cicada, according to both m-w.com and dictionary.com, is pronounced as an "s". I've heard people pronounce it as only a "ch" sound. And I myself pronounce it as "ch". BTW, those two dictionaries also provide long/short vowel pronunciation options of "i", and the first "a".

I have listed some links about cicadas, many of them YouTube videos that show cicadas molting.
Anyway, the bottom line about the clinging bug shell on the porch column: It's a castoff exoskeleton after a cicada molts and flies away, not shell remains after parasitic larva(e) dined on the insect. Coincidentally enough, a wasp that captures a cockroach for its larva's future food supply uses similar methodology as a wasp that targets cicada.

From "10 Facts about Cicada Killer Wasps"
  1. The adult female wasp will paralyze the cicada with her venomous sting.
  2. The wasp will carry the cicada to a burrow, where it will place the cicada.
  3. The wasp will lay an egg under the left or right second leg of the cicada.
  4. The egg hatches, and the larvae begins to eat the cicada, while taking care to keep it alive.
  5. Once the larvae [sic] has had its fill, it spins a cocoon, in which it will change into an adult wasp.
Such behavior looks similar to that of jewel-wasp-on-cockroach, in comparing information in "How a Wasp Turns Cockroaches into Zombies" of Scientific American.
venom compounds work fast, paralyzing the cockroach …
leads her victim to its final resting place …
Once inside her burrow, she attaches one egg to the cockroach's leg, then seals her offspring and the roach in.…
wasp larva hatches from its egg, its meal is ready to eat. And soon enough after that, a new wasp emerges from the burrow, leaving the roach carcass behind.
Note: The SA article states that the larva hatches and emerges as a wasp, omitting the details of how the larva becomes a wasp. The m-w.com site explains that the stage between larva and wasp is pupa, "usually enclosed in a cocoon or protective covering".

For more articles about cicadas, enter "cicada" in the search box at the upper left of this window. Or find and click "cicada" link at Partial Index of Keywords section (just below Popular Posts section).