prove to be another important factor in solving questions concerning the food supply of ants under both ordinary and extraordinary circumstances. Mr. Edwards is now pushing his observations upon the Spring larvæ of this butterfly, assisted by the microscopic skill of Prof. J. Gibbons Hunt, M. D., of Philadelphia.

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THE SMALLEST INSECT KNOWN (PTERATOMUS PUTNAMII).

THE

BY HON. J. D. COX.

HE minute size of this species, which is said to be the smallest insect known, is probably the reason why it has been so little observed, and will justify a somewhat detailed description of a specimen which was caught and mounted in balsam last July.

I was examining the scissor-like mandibles of a leaf-cutter bee (Megachile centuncularis), when I noticed upon the surface of the water in which the larger insect was dissected, a mere mite which seemed to have life. Upon transferring it to a smaller cell of water and putting it under the microscope, it proved to be one of the most beautiful little creatures of the insect world, and a rarity which made it no ordinary prize.

Whilst it was not difficult to identify it as the Pteratomus Putnamii from Prof. Packard's description in the "Guide to the Study of Insects," it was also evident that the specimen which the Professor had before him in making his drawing and description, had been injured, and shorn of some of its parts, and that something might be added to our knowledge by putting the "winged atom" in shape for permanent preservation.

The first suggestion as to method was acted upon at a venture, and it turned out a rather lucky hit. A clean slide and cover, and the soft balsam were at hand. Her littleness was taken carefully on the point of a needle, dried against a bit of blotting paper, immersed in a drop of balsam and the cover put on, leaving the arrangement and display of the parts almost wholly to the effects of capillary attraction.

The cut is from an accurate tracing by means of the camera, and except as to the position of the wings, will give at once a correct idea of the little creature. The wings were forced somewhat out of place in the mounting, but with the aid of the binoc

ular microscope there was no great difficulty in seeing the proper connection and natural places of the parts.

The body was found by micrometer to be twelve thousandths of an inch in length, the antennæ, twenty thousandths. The head is comparatively large and plump, the longitudinal diameter being to the transverse as eight to five. The compound eyes when

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seen in outline show eleven facets in section from front to rear; they are of a bright brownish-red color. Three ocelli or stemmata are seen on the top of the head, the middle one lunate in shape with concave side toward the front. These are separated from the forehead by a bow-shaped band having alternately dark and light divisions. The under side of the head with the mouth parts are shown at B in the woodcut, and these last are exceedingly minute. All that can be clearly made out are two curved and pointed mandibles with faint traces of mouth opening, but no projecting ligula or proboscis

The antennæ are very slender, consisting of ten joints, of which the first curves outward, with a distinct tooth on the inner side near the upper end; the second is oval, being only half the length of the others and broader; the remaining joints do not seem to be perfectly round, but rather four-sided, with points or teeth at the upper end of all except the last, which terminates in a tapering tip.

The thorax is the largest part of the body, equaling in bulk the head and abdomen together. The prothorax, mesothorax and metathorax are nearly equal in size, as may be seen by the divisions of the back which are shown in the figure.

The wings are linear, of sigmoid curvature, with three or more longitudinal lines of minute hairs on the faces, and fringed at the edge with comparatively long ones, which have a black medulla or pith in the greater part of their length, but the inner part, next the body of the wing, is so transparent as to be hardly visible, and gives to the fringe the appearance of being separated from the wing, though with high magnification the hairs can be traced through their entire length. In mounting this specimen the wings of the left side were partly torn from their place and reversed, so that the fore wing is that which is seen in the figure nearest the rear of the body, and the hind wing is that which appears to have its socket nearest the head of the insect. Their proper origin is in fact at a, whilst at b, careful examination shows a slight projection or shoulder on the fore wing where a corresponding part marked b' on the hind wing articulates with it when both are in proper position.

The legs are nearly as long in proportion to the body as those of the common mosquito. The tarsi are five-jointed. The tibial spurs are large and strongly developed on the fore legs, as shown at c and c' in figure, and opposite them on the first joint of the tarsus the fringe of hairs is very noticeable, which is sometimes called the "comb" in larger insects. The tibial spurs are insignificant on the other legs. The foot-pads or pulvilli, with the claws are so minute as to be scarcely distinguishable even under a power of four hundred diameters.

The abdomen is pediceled, and is very short and obtuse, its longitudinal diameter being rather less than its transverse. It is so opaque that the rings can only be well seen at the edge where they appear as in section, and where they have a pronounced appearance of being telescoped, the edges passing beyond each other as if the abdomen had been flattened in the direction of its length. I should have thought this an accidental condition of the present specimen, but for the fact that Prof. Packard found it the same in the one described by him. Five rings can be distinctly made out, with the probability of a sixth, and perhaps a seventh. Upon the under side of the abdomen a long spike-shaped ovipositor is seen, whose form and dimensions are shown in the second outline of the abdomen at C in the figure.

This description of the Pteratomus, of which all the parts have been carefully verified, corroborates collaterally the opinion of

Prof. Packard, as to its habitat as a probable egg-parasite upon the Megachile or upon another parasite of this bee, and agrees with the measurement he made of its size and the description of such parts as his probably damaged specimen enabled him to determine, except in an important particular of the wings. In the example before me I find the wings entire, not fissured. This would have induced doubts as to the species had not Prof. Packard himself seen this specimen and concurred with me as. to its identity.

It is not improbable that the dissection of other leaf-cutter bees in water, might lead to the washing off and securing of other specimens of this minutest of Hymenoptera, and the beauty of the little insect itself, with its rarity, would well repay the naturalist for some pains in adding it to his collection.

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THE ROBIN'S FOOD.·

BY DAVID ALEXANDER LYLE.

N the morning of May 28th, of last year (1877), I found a robin's (Turdus migratorius) nest, about 27 feet from the ground, in a fir tree. It was placed on horizontal twigs near the top. The materials of this nest were the dried blades and roots of grasses. A string over four feet long was found looped around one of the limbs on which the nest was built, but no part of its length was incorporated in the structure. Notwithstanding the protestations of the old birds, I took the ugly-looking thrushlet from the nest and carried it home, with the intention of rearing it to maturity if possible. I procured a large rectangular wire cage, in which, with all due tenderness, I installed my foundling. I furnished him plentifully with stores of boiled eggs and mashed potatoes, mixed as prescribed by those paragons of female character who are self-constituted authorities upon the subject of avian cuisine. I placed conveniently for his use a bath of pure water, and also filled his water-cup. Yet, in the midst of all these delicate attentions, my baby bird steadfastly maintained an air of utter indifference. He neither ate nor drank, but sat, all drawn up on the bottom of the cage, giving vent to an occasional weak chirp. I tried to make him eat by taking little pieces of bread and hardboiled egg in my fingers and approaching them to his bill after

the manner of the old bird, but to no purpose, his mandibles seemed to be hermetically sealed.

Finding all attempts to coax this exasperating bird to eat in vain, I concluded to forego moral suasion, and try what virtue there was in physical coercion. I opened his mandibles and put small pieces of bread, potatoes and boiled egg so far down his throat that he had to swallow them. I quenched his thirst in a similar manner by pouring a few drops of water at a time into his pharynx. This treatment revived the patient somewhat, but did not give entire satisfaction; I then began feeding him on raw beefsteak three times a day, morning, noon and night, giving him bread and egg in the intervals.

The effect was magical, his eyes brightened, his chirping became loud and vigorous, he would hop about briskly, and continually attempted to get out of the cage between the wires. I found that after eating he became very wild and would not allow my hand to approach him.

He soon learned to open his mouth to receive the food I offered, and henceforth gave no trouble in feeding. I next began to feed him with common earth worms, permitting him to eat nothing else for two or three days. He would eat until his crop could contain no more, then he would retire to his perch, draw down his neck as if suffering, close his eyes, drop his wings a little, and sit perfectly still for about fifteen or twenty minutes. At the end of that time he had digested the worms sufficiently to be ready for another meal. A strictly vermicular diet did not seem to agree well with him, it apparently acted as a laxative. I then alternated between raw beefsteak and earth worms, and found that when he could get beefsteak he would refuse the worms. It being the proper season for June beetles, and as they were easily collected in great numbers, I tried this species as a food, and learned with pleasure that he preferred them to anything else.

Forthwith I procured a wide-necked pickle bottle, and every night had a quantity collected for his daily rations. Henceforth, as long as these Coleoptera could be found in sufficient numbers, they were his sole food.

When they were given him alive he would seize them with his bill, and by vigorous shaking and pounding upon the bottom of his cage, would kill them and remove the elytra before swallowing