These Giant Swallowtail larve (Papilio cresphontes) were chomping away at one of my grapefruit trees this afternoon. In extreme close-up they are quite fascinating creatures.
I could hear them eating as they devoured the tree's leaves. The caterpillar has evolved a resemblance to bird droppings to deter their main predators, birds.
If the caterpillar's camouflage isn't enough deterrence, they use red osmeterium which distend from their heads and resemble horns. These guys did not feel adequately threatened by me sticking the camera in their faces, probably because they were so full from devouring the grapefruit tree and because it was very late in the day. In a 2009 post I captured some of the caterpillars with the osmeterium distended (link below).
See my 2009 post where the caterpillars were displaying their osmeterium.
The osmeterium is a fleshy organ found in the prothoracic segment of larvae (caterpillars) of Swallowtails and Birdwings. The organ emits pungent compounds believed to be pheromones. Locals call these caterpillars "orange dogs" because of the coloration of the osmeterium.
Above and Below: These are some Giant Swallowtails feeding. I let the butterflies and caterpillars eat what they want. There's plenty.
While I would never think to eat one of these caterpillars, there are plenty of television shows that encourage that sort of activity (think Man vs. Wild, Dual Survival, and Man, Woman, Wild).
What they may not explain well on those shows is that larvae, snails, and slugs ingest toxins and parasites from the environment. If another organism ingests the larvae, snail, or slug they ingest the toxin or parasite as well.
Some examples:
A recent Australian story illustrates why it might be a good idea to cook anything one chooses to eat from the garden.
Above: A common Garden Slug or snail (Helix aspersa).
In May, news.com.au (Australian News) reported that a Sydney man became critically ill after eating a slug (or garden snail) as a dare, leading authorities to issue health warnings on eating raw gastropods.
The 21-year-old contracted rat lungworm disease - a rare form of meningitis - after the stunt.
Rat lungworm disease is caused by Angiostrongylus cantonensis, a parasitic worm that is carried in the pulmonary arteries of rats. Larvae are excreted in the rat's droppings, which are often eaten by slugs and snails.
The disease can cause fatal swelling of the brain and spinal cord.
However, Jeremy McAnulty from New South Wales Health said most people do recover. He said the worm goes away by itself because the body's immune system eventually gets rid of it.
Dr. McAnulty said people should not eat raw slugs or snails and should ensure they wash their hands after touching them.
"It is also important to thoroughly wash and cook any produce that could be contaminated by animals," he said.
The worm was found mainly in Asia and the Pacific Islands. It was rare for people to contract rat lungworm disease in Australia, but it occurred occasionally from eating an uncooked slug or snail, Dr. McAnulty said.
Above: Angiostrongylus cantonensis in its third stage recovered from a slug. Read more at the Centers for Disease Control and Prevention.
Infected people may have no symptoms or only mild short-lived symptoms, he said.
Sometimes the infection causes meningitis, with symptoms such as headaches, stiff neck, tingling or pain in the skin, fever, nausea, and vomiting.
"Even if infected, most people recover fully without treatment," he said. "However, it can sometimes cause severe meningitis. Because humans are not the natural host of the parasite, the parasite eventually dies without treatment."
Rat lungworm infection cannot be passed on to other people.
Another example:
OLEANDER POISONING
Above: Oleander. We have several very large specimen of this toxic plant. The plant is native to Morocco and Portugal.
The New York Times recently reported (without much elaboration) that individuals had become sickened with erratic heart rhythms after eating stew made from snails that had eaten oleander leaves, which contain cardiac glycosides (like digoxin; a purified version of what is found in the oleander plant).
CDC ISSUES HEALTH ADVISORY
FOR FLORIDA SNAILS
Above: A giant land snail (Achatina spp.). One should wash their hands thoroughly after taking a photo like this one.
The Centers for Disease Control and Prevention has issued a Health Advisory in Florida regarding Giant African Land Snails (Achatina spp.) In part the advisory says that the snails could pose a public health threat if infected with Angiostrongylus cantonensis.
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