Pap. P. R. Venus, Fabr. Mantissa.—Hesperia R. Venus, Fabr. Systema.—Pap. Venus, Herbst. Pap. Pl. 294, fig. 1, 2. Pap. Imperialis, Cramer, Pl. 76. fig. E, F.
This beautiful little insect is not unlike the preceding both in its form and colours. It belongs to a section of Polyommatus, in which the upper wings of the male are marked with an orbicular spot, of a cottony appearance, and frequently a good deal impressed. The expansion of the wings does not exceed an inch and a half. The colour of the surface is brilliant blue, the costa and outer margin of the wings black, and the disk of each marked with two ferruginous points in the male. Beneath, the colour is likewise green, richly glossed with golden yellow, the anterior portion of the under wings transversely streaked with narrow black marks. The tails are wholly black.
All the examples hitherto brought to Europe seem to be from Surinam.
POLYOMMATUS ACHÆUS.
PLATE XXVII. Figs. 3, 4.
Hisperia R. Achæus, Fabr.—Pap. Achæus, Cramer, Pl. 352, fig. G, H.—Herbst. Pap. Pl. 297, figs. 3, 4.
Nearly the same size as P. Venus, and also a native of Surinam. Upper side dark brown, the superior wings with two oval yellow spots on the disk of each, and two transverse curved streaks of the same colour on the inferior, the anal angle with a ferruginous spot. Under side yellow, with numerous ferruginous patches, each of which is ornamented with several small spots of golden-yellow, the outer border with a continuous ferruginous band bearing a series of golden-yellow elongated spots. Body brown above and yellowish beneath.
Genus THALIURA.
The genus to which we have assigned the above name has been hitherto blended with the Uraniæ. It is doubtless very closely connected with these insects; but the differences both in the appearance of the perfect insects and the respective caterpillars, render it expedient that they should be separated. The character by which it and Urania are widely separated from all others, is the form of the antennæ, which are filiform nearly to the middle, where they thicken a little, and from that gradually narrow to a point. The palpi are lengthened and slender, having the second joint greatly compressed, the terminal one more slender, nearly cylindrical, and naked. There is no closed discoidal cell in any of the wings, and almost all the nervures diverge from the base. Not many different kinds are known, and, with one exception, they are natives of America and the West Indian Islands. Their splendid tints of golden green arranged in transverse bars, render them perhaps the most chastely beautiful insects that exist, and has caused them to be named Emerald Butterflies in this country. Sometimes also they are called Pages. They fly so high in the air and with so much velocity, that it is nearly impossible, Madam Merian informs us, to catch them, and the only way therefore to obtain good specimens, is to feed the caterpillar. “Great numbers of this insect,” says Mr. Swainson, speaking of a species almost the exact counterpart of U. Leilus, “were flying during the whole of the morning, past Aqua Fria (Pernambuco) in a direction from north to south: not one deviated from this course, notwithstanding the flowers which were growing around: they flew against the wind, which blew rather strong, and near the ground, but mounted over every tree or other high object which lay in their course; yet their flight was so rapid, that I could not capture a single specimen. They went singly, and near fifty or sixty must have passed the spot opposite the window before mid-day: they continued to pass for three or four days in this manner. 12th June 1817[37].”
The present genus differs from Urania in the perfect insect having three distinct tails at the hinder extremity of the posterior wings; neither are these wings so much elongated as in the group just named. The differences between them in their early states will be seen by comparing the following descriptions.