Scientific American Supplement, No. 344, August 5, 1882

by Various

On the trees were to be seen--Attacus cynthia (the Ailantus silkworm), the rearing of which was, as usual, most successful; Samia cecropia and Samia gloveri, from America; also hybrids of Gloveri cecropia and Cecropia gloveri; Samia promethea and Telea polyphemus; Attacus pernyi, and a new hybrid, which I obtained this last season by the crossing of Pernyi with Royle. For the first time I reared Actias selene, from India, on a nut-tree in the garden, and Attacus atlas, on the ailantus. The Selene larvæ reached their fifth and last stage. The Atlas larvæ only reached the third stage, and were destroyed by the heavy rains; only two remained on the tree till about the 8th or 9th of September, when they had to be removed. I shall now reproduce the notes I took on some of the various species I reared.

Actias Selene.--With sixty cocoons I only obtained one pairing. The moths emerged from the beginning of March till the 13th of August, at intervals of some duration, or in batches of males or females. I obtained a pairing of Selene on the 30toh of June, 1881, and the worms commenced to hatch on the 13th of July. The larvæ in first stage are of a fine brown-red, with a broad black band in the middle of the body. The second stage commenced on the 20th of July; larvæ, of a lighter reddish color, without the black band; tubercles black. Third stage commenced on the 28th of July; larvæ green; the first four tubercles yellow, with a black ring at the base; other tubercles, orange yellow. Fourth stage commenced on the 6th of August; larvæ green; first four tubercles golden-yellow, the others orange-red. Fifth stage commenced on the 19th of August; first four tubercles yellow, with a black ring at the base; other tubercles yellow, slightly tinged with orange-red; lateral band brown and greenish yellow; head and forelegs dark-brown. As stated before, the larvæ were reared on a nut-tree in the garden, till the last stage. Selene feeds on various trees--walnut, wild cherry, wild pear, etc. In Ceylon (at Kandy), it is found on the wild olive tree. As far as I am informed by correspondents in Ceylon, this species is not found--or is seldom found--on the coasts, but Attacus atlas and Mylitta are commonly found there.

Attacus (antheroea) roylei (with sixty cocoons); three pairings only were obtained, and this species I found the most difficult to pair in captivity. Two moths emerged on the 5th of March, a male and a female, and a pairing was obtained; but the weather being then too cold, the ova were not fertile, the female moth, after laying about two hundred eggs, lived till the 22d of March, which is a very long time; this was owing to the low temperature. The moths emerged afterward from the 8th of April till the 25th of June. A pairing took place on the 2d of June, and another on the 6th of June.

Roylei (the Himalaya oak silkworm) is very closely allied to Pernyi, the Chinese oak silkworm; the Roylei moths are of a lighter color, but the larvæ of both species can hardly be distinguished from one another. The principal difference between the two species is in the cocoon. The Roylei cocoon is within a very large and tough envelope, while that of Pernyi has no outer envelope at all. The larvæ of Roylei I reared did not thrive, and the small number I had only went to the fourth stage, owing to several causes. I bred them under glass, in a green-house. A certain number of the larvæ were unable to cut the shell of the egg.

Here are a few notes I find in my book: Ova of Roylei commenced to hatch on the 29th of June; second stage commenced on the 9th of July. The larvæ in the first two stages seemed to me similar to those of Pernyi, as far as I could see. In second stage, the tubercles were of a brilliant orange-red; on anal segment, blue dot on each side. Third stage, four rows of orange-yellow tubercles, two blue dots on anal segment, brilliant gold metallic spots at the base of the tubercles on the back, and silver metallic spots at the base of the tubercles on the sides. No further notes taken.

One of my correspondents in Vienna (Austria) obtained a remarkable success in the rearing of Roylei. From the twenty-five eggs he had twenty-three larvæ hatched, which produced twenty-three fine cocoons. The same correspondent, with thirty-five eggs of Samia gloveri, obtained twenty cocoons. My other correspondents did not obtain any success in rearing these two species, as far as I know.

Hybrid Roylei-Pernyi.--I have said that it is extremely difficult to obtain the pairing of Roylei moths in captivity. But the male Pernyi paired readily with the female Roylei. I obtained six such pairings, and a large quantity of fertile ova. The pairings of Roylei (female) with Pernyi (male) took place as follows: two on the 21st of May, one on the 3d of June, two on the 4th of June, and one on the 6th.

The larvæ of this new hybrid, Roylei-Pernyi, contrary to what might have been expected, were much easier to rear than those of Roylei, and the cocoons obtained are far superior to those of Roylei, in size, weight, and richness of silk. The cocoon of my new hybrid has, like Roylei, an envelope, but there is no space between this envelope and the true cocoon inside. Therefore, this time, the crossing of two different species (but, it must be added, two very closely allied species) has produced a hybrid very superior, at least to one of the types, that of Roylei. The cocoons of the hybrid Roylei-Pernyi seem to me larger and heavier than any Pernyi cocoons I have as yet seen.

The larvæ of this new hybrid have been successfully reared in France, in Germany, in Austria, and in the United States of North America. The cocoons obtained by Herr L. Huessman, one of my German correspondents, are remarkable for their size and beauty. The silk is silvery white.

I have seventeen cocoons of this hybrid species, which number may be sufficient for its reproduction. But the question arises, "Will the moths obtained from these cocoons be susceptible of reproduction?"