Atlas Moth

Description:

Saturniidae; Saturniinae; Attacini; Attacus atlas (Linnaeus, 1758). "The Atlas moth is one of the largest lepidopterans, with a wingspan measuring up to 24 cm (9.4 in) and a wing surface area of about 160 sq.cm (~25 sq. inches)." Wikipedia.

Habitat:

These Atlas Moth larvae were spotted approximately 15 to 20 ft. above the ground on a Mahogany Tree in our back yard. So that has answered the question of Habitat, but gives rise to another question. See notes below.

Notes:

What were these larvae doing so high up when they are clearly in danger of falling. (I should point out that these trees are 30 to 35 feet tall at present. So the larvae were not in the top layers of the canopy, but certainly very high). Yes, I know....I can almost hear all the lepidopterists out there.... the sighs accompanied by rolling of the eyes. But bear with me a moment please. I am somewhat familiar with Saturniidae (having raised many from eggs) and I admit that the larvae have an immensely powerful grip, especially the prolegs (so much so that one has to be extremely patient in handling them. If a larva decides to hold tight to your finger, you better be ready to wait as long as it takes for it to decide it wants to let go. If you are impatient and try to pull it off, you will damage it). So what's all the fuss about the height up in the tree. Firstly, there is more than ample foliage to eat on the lower branches. Secondly, at higher levels, the branches are thinner and whip around in the wind rather than sway as the lower branches do. Thirdly, when it rains the upper twigs and foliage are much more exposed and as a result will become much more slippery than those at more sheltered levels. (I agree that the prolegs still have some grip on wet substrates and the true legs will grip by biting into bark and leaves in any conditions). So where am I going with this? Over the years, I have found several larvae of this species on the ground, under this row of Mahogany trees. In the early days of my developing interest in wildlife, I am sure that I mistakenly considered this to be normal. The larvae had simply walked all the way down the trunk of the tree to the ground because they were ready to pupate in a little underground nest. Right? No, totally wrong. I must have been confused (due to my lack of knowledge at the time) by the fact that many Hawk Moth larvae pupate underground and up to that time I had some experience of breeding Sphingidae, but not yet Saturniidae. Obviously, at that time, I had no idea that Saturniids pupate in silk cocoons attached securely to twigs or leaves on their host tree. I also did not know that those which I found on the ground were not final instars (and not ready to pupate). So, what is the answer to my conundrum ? Why are the larvae so high in the tree. The short answer is: I don't know. The longer answer is that I have a slightly hare-brained idea. If a larva is in the lower layers of the tree, it could be spotted by sparrows and sundry other birds which spend at lot of time on the ground, pecking and scratching, and occasionally fly up into the lower branches of trees. On the other hand, if the larva spends its time on the the topmost branches, it risks being snatched by other categories of birds which fly over the canopy. In the middle layers, it will not enjoy complete protection from the elements which carries some risk of being thrown down in wild weather conditions, but probably reduces its exposure to predation which may be a greater threat than falling. This may be nonsensical, I don't know. But I just can't keep finding fallen larvae without trying to rationalize why it is happening. If you have been sufficiently patient to read this and you know the answer, please let me know. I am always open to better solutions if they are out there.