Naturespeak A naturalist's view of the world

July 27, 2013

A Carnivorous Butterfly

Filed under: Uncategorized — wykes @ 9:23 am

It was attached to the hood of my truck, on the driver’s side, and hanging on for dear life. I’m not sure when it arrived at that spot but because it was soon to depart I pulled into a parking place and rushed out to get a few pictures before the thing was swept away. The temperature was already soaring into the 80’s and the wind was gusting hard. Each blow caught the wings and laid the delicate creature on its side. Yet, it held onto the slick surface as if glued.  Oh, I forgot to mention that the “it” was an unfamiliar butterfly of small stature displaying some fascinating underwing décor.

I leaned awkwardly over the hood and attempted to capture a portrait of the butterfly as best I could. A pair of folks entering the nearby store looked over just long enough to make sure that I wasn’t having some sort of seizure there on the car hood. They could not have seen the tiny subject before my lens. Detecting no drool from my tortured frame, they probably chose to leave me to my own. Fortunately they did not ask what I was doing. I would have been forced to tell them I didn’t know the exact identity of the insect I was so earnestly examining.   Afterward I pegged the creature as a Harvester Butterfly – or, as it is often written: “The Harvester” (as in THE Ohio State University”).

Harvesters are not your run of mill flower-sucking butterflies. Harvesters are carnivorous. Well, to be precise, their larvae are the predatory ones. They are the ONLY predatory butterfly or moth larvae in North America – a single species within a single genus.  Considering that every other God-fearing caterpillar on the continent is a strict vegetarian, this represents quite a departure from the norm. The chosen Big Mac for Harvester larvae are rather unappetizing looking creatures called Wooly Aphids (Woolly Maple, Alder, and Beech Aphids).

Beech Blight Woolly Aphid Colony

Harvester caterpillars live amongst the slow moving woollies and eat them at their leisure. Four sharp teeth on their mandibles facilitate their predatory pursuits. The larvae sometimes decorate their bodies with the hollow corpses of their victims and because they exude aphid odor they are unmolested by the ants that often tend the aphid colonies.

I’m not sure there is a lesson here for you vegetarians out there, but meat-eating Harvester larvae grow much quicker than their vegetarian cousins. Instead of the usual 5 stages, or instars, they complete their growth with only 4 instar stages and  do it in as little as 8 days.  Their final shedding produces a pupa which looks like a monkey face mask. Odd? Yes, they are.

The adult Harvesters, in spite of their bloody childhood, look like normal butterflies. The underside of the wings is delicately speckled with burnt sienna spots outlined with cream borders. I wasn’t able to convince my semi-captive butterfly to reveal the upper side of its wings. In fact, when I tried to pry them open it took great exception to my intrusion and flew off. As a matter of record, they were deep orange with a broad black border pattern.

The only thing that defines the adult insects as “being different” from other butterflies is the presence of a very short tongue or proboscis. Harvesters abandon their predatory ways and resort to sucking nutrients from sap, mud, carcasses, and – no surprise here- aphid honey dew (aphid doo).  This short tongue is an adaptation towards this goal. Flower-feeding butterflies require long tongues for probing flowers. Licking doo from the rear end of an aphid only requires a short straw.

In looking over my photos after my Harvester encounter, I did notice that I was apparently parking in the Handicap spot at the store. Take a good look at the photo and you’ll see the blue sign clearly reflected on the hood of my truck. Ah, so that’s why those people were looking at me so oddly!

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