Short as is the eastern twilight, it has its own peculiar forms, and the naturalist marks with interest the small, but strong, Hesperidæ[4263], hurrying, by abrupt and jerking flights, to the scented blossoms of the champac or the sweet night-blowing moon-flower; and, when darkness gathers around, we can hear, though hardly distinguish amid the gloom, the humming of the powerful wings of innumerable hawk moths, which hover with their long proboscides inserted into the starry petals of the periwinkle.
Conspicuous amidst these nocturnal moths is the richly-coloured Acherontia Satanas, one of the Singhalese representatives of our Death's-head moth, which utters a sharp and stridulous cry when seized. This sound has been conjectured to be produced by the friction of its thorax against the abdomen;—Reaumur believed it to be caused by the rubbing of the palpi against the tongue. I have never been able to observe either motion, and Mr. E.L. Layard is of opinion that the sound is emitted from two apertures concealed by tufts of wiry bristles thrown out from each side of the inferior portion of the thorax.[4271]
Moths.—Among the strictly nocturnal Lepidoptera are some gigantic species. Of these the cinnamon-eating Atlas, often attains the dimensions of nearly a foot in the stretch of its superior wings. It is very common in the gardens about Colombo, and its size, and the transparent talc-like spots in its wings, cannot fail to strike even the most careless saunterer. But little inferior to it in size is the famed Tusseh silk moth[4272], which feeds on the country almond (Terminalia catappa) and the palma Christi or Castor-oil plant; it is easily distinguishable from the Atlas, which has a triangular wing, whilst its is falcated, and the transparent spots are covered with a curious thread-like division drawn across them.
Towards the northern portions of the island this valuable species entirely displaces the other, owing to the fact that the almond and palma Christi abound there. The latter plant springs up spontaneously on every manure-heap or neglected spot of ground; and might be cultivated, as in India, with great advantage, the leaf to be used as food for the caterpillar, the stalk as fodder for cattle, and the seed for the expression of castor-oil. The Dutch took advantage of this facility, and gave every encouragement to the cultivation of silk at Jaffna[4281], but it never attained such a development as to become an article of commercial importance. Ceylon now cultivates no silkworms whatever, notwithstanding this abundance of the favourite food of one species; and the rich silken robes sometimes worn by the Buddhist priesthood are imported from China and the continent of India.
In addition to the Atlas moth and the Mylitta, there are many other Bombycidæ; in Ceylon; and, though the silk of some of them, were it susceptible of being unwound from the cocoon, would not bear a comparison with that of the Bombyx mori, or even of the Tusseh moth, it might still prove to be valuable when carded and spun. If the European residents in the colony would rear the larvæ of these Lepidoptera, and make drawings of their various changes, they would render a possible service to commerce, and a certain one to entomological knowledge.
Stinging Caterpillars.—The Dutch carried to their Eastern settlements two of their home propensities, which distinguish and embellish the towns of the Low Countries; they indulged in the excavation of canals, and they planted long lines of trees to diffuse shade over the sultry passages in their Indian fortresses. For the latter purpose they employed the Suriya (Hibiscus populneus), whose broad umbrageous leaves and delicate yellow flowers impart a delicious coolness, and give to the streets of Galle and Colombo the fresh and enlivening aspect of walks in a garden.
In the towns, however, the suriya trees are productive of one serious inconvenience. They are the resort of a hairy greenish caterpillar[4291], longitudinally striped, great numbers of which frequent them, and at a certain stage of growth descend by a silken thread to the ground and hurry away, probably in search of a suitable spot in which to pass through their metamorphoses. Should they happen to alight, as they often do, upon some lounger below, and find their way to his unprotected skin, they inflict, if molested, a sting as pungent, but far more lasting, than that of a nettle or a star-fish.
Attention being thus directed to the quarter whence an assailant has lowered himself down, the caterpillars above will be found in clusters, sometimes amounting to hundreds, clinging to the branches and the bark, with a few straggling over the leaves or suspended from them by lines. These pests are so annoying to children as well as destructive to the foliage, that it is often necessary to singe them off the trees by a flambeau fixed on the extremity of a pole; and as they fall to the ground they are eagerly devoured by the crows and domestic fowls.[4301]