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The Horror Beside You-Blue Butterfly

Mar 13, 2014 by

The Horror Beside You-Blue Butterfly


The Horror

In any discussion of  weird Animals, the Large Blue Butterfly (Phengaris arion) from Britain, and its fellow species of butterfly in the Lycaenidae family, is certainly one of the more startling stories of the animal world. It reads as a page from monster fiction of a lurid kind. The “Alien,” story is easily conjured up or something primal, old and blood curdling from HP Lovecraft or Robert E. Howard. Only here the beauty IS the beast!

Blue Butterfly

Hail the beautifully weird animals of the world; The Blue Butterfly. [http://www.flickr.com/photos/25801055@N00/2583995167/ Large Blue http://creativecommons.org/licenses/by-sa/3.0/deed.en

 3. Bacteria Linearis stick insect

The Large Blue Butterfly is usually seen flying during the last week in June and through July. It is a small butterfly, perhaps 2 inches from black speckled wing tip to wing tip. It flutters close to the grass and the females can be seen depositing their tiny eggs on the petals of wild thyme flowers, (Thymus drucei).

Once the caterpillar emerges from the egg, and for about 3 weeks, it feeds on the downy exterior of the flowers, working its way to the base of the petals. But aside from its vegetable food, normal faire for caterpillars, it will greedily devour any other small caterpillars that it may meet, becoming voraciously cannibalistic. The caterpillar will stay near its food-plant until its 4th instar, (shed) then it will drop to the ground.

From there the Blue Butterfly caterpillar walks off. It walks, until by “chance,” it is found by Myrmica ants. The eggs were laid by the mother insect on tufts of thyme that are growing upon ants’ nests, just so the caterpillar maybe found by these specific ants!

Blue Butterfly



Several caterpillar species of the Phengaris Blue Butterfly, including P. rebeli and P. alcon  secrete pheromones that are unique to their perspective ant hosts. These mimic the pheromones of ant larvae that will become workers. At their initial meeting, the caterpillar shows no sign of recognizing its future host, but the ant certainly recognizes the caterpillar. The ant will begin at once to stroke and caress the caterpillar with her antennae and feet.

On the tenth segment of the caterpillar there is a pore which has the power of secreting and exuding a sweet kind of “honey-dew.” As soon as the ant begins her caresses, the caterpillar exudes a drop of dew, which the ant sucks up. Other ants may come and join in this ‘wooing’ of the caterpillar, and subsequent milking. Many drops of dew are exuded in one of the strangest bribes of the natural world.

The Blue Butterfly caterpillar prepares itself to be carried off. It gives the signal to the ant by swelling up the thoracic segments. The ant, on receiving this signal, strides the caterpillar, seizes it gently in its mandibles, holding it immediately behind the hunched thoracic segments. It then sets off carrying the caterpillar to its underground nest, and deposits it in one of the chambers where the young ant grubs are nurtured.

Blue Butterfly

The fooled myrmica ant carries the caterpillar to its nest.

Blue Butterfly


By successfully mimicking ant larvae, the caterpillars are taken back to the host nest. Once there, one of two stratagems are employed. Most caterpillars exude a “virgin queen” odor. Making the workers believe that it is a larval queen, that out ranks the worker larvas. As such it will be fed by the ants to the exclusion of, and starvation of, the other larvas. Even going so far as to rescue it over the others should the nest be attacked. If the actual queen shows up the caterpillar will switch its scent to that of a worker larva! This is done because queens will kill queen larva if they find them, as these larva represent a potential threat to the living queen.

The second weird animals stratagem is straight out of a horror fiction book. The caterpillar takes on the odor of a worker larva and begins devouring the ant larva beside it! It’s awareness is such that it can find the eldest larva, kill, and eat it first, as it would be the caterpillar’s primary rival for food and attention. The caterpillar munches and crunches its way through larva, growing to several times the size of its “siblings.”

Death can come suddenly. A lack of food seems to make the ants nervous and they can become suspicious of this giant in their midst. Or sometimes the mimicry is a just slightly off due to the wrong species of ant responding to the lure. Once the true identity of the Blue Butterfly impostor is known its death is a certainty.

Blue Butterfly


All through the remaining weeks of the summer the caterpillar feeds on the ant larvae. Come autumn it hibernates in the cell, underground, together with it’s adopted ant “family.” The spring wakes it up, and it begins feeding on the juvenile ants again. In late May or early June it will pupate.

It may have spent 9 months as a juvenile, it’s entire adult life is a matter of weeks. For three weeks it will rest in the chrysalis, it then emerges as a butterfly in surely the last place one expects to find a butterfly; the dark, dank tunnels of an ant maze. Its wings are unexpanded, like shriveled leaves, they droop on either side of its body. Ants will devour butterflies; but this butterfly, crumpled, helpless, deep within their nest, the one-time devourer of their children, is freed to crawl up through the dark passages towards the light.

Though the Blue Butterfly’s equipment for its elaborate ruse and its baby ant-eating jaws are gone, it’s not defenseless. The honeydew cannot be made, nor can it make the smell of a larva, but it’s covered with a sheen of fine white powdery scales. If ants object to this alien leaving their nest they are welcome to try and stop it. The white scales cannot be grabbed, grappled or climbed upon. The butterfly flees to, and out of, the entrance bowling over confused ants as it goes.

Blue Butterfly



The Blue Butterfly crawls up a grass stem, losing the white scaly powder as it climbs. There it begins a rhythmical pumping which fills the veins of the wings with yellowish-green “blood.” The wings expand and hang over the back, folded together. They harden, to the necessary firmness and spread out. Then it uncoils its long proboscis mouth preparing to innocently sip nectar.

If the Blue Butterfly is a female she will be mated before her wings are dry. Even as she climbs the grass stalk her scent has already alerted several interested males nearby and they are quick to her side.

This weird animals’ life history is complete and the Blue Butterfly, who presumably, is completely unconscious of its cannibalistic childhood and its ant-devouring adolescence, begins the horrendous amazing cycle all over again.




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