Imágenes de páginas
PDF
EPUB

resembles, more nearly than No.2, the coprolites of England, as analyzed by Herepath, but gives much less lime carbonate. An analysis of fossil bone, from the greensand beds of Virginia, is here appeuded: Moisture and organic matter....

1.50 Insoluble silicates and sand....

17. 40 Phosphate of iron and alumina

10.94 Phosphate of lime....

55.20 Carbonate of lime...........

12. 60 Magnesia......

trace Soluble salts, chiefly chlorides....

2. 30

[ocr errors]

The bones were found in the Potomac River when raking oysters below Aquia Creek. By soaking in brackish water, and by deposit, they have undergone some alteration, even from those found in the greensand beds.

It is still interesting to observe how large an amount of lime phosphate is preserved after so long-continued solvent action of the weak saline water of the Potomac River at that point.

THOMAS ANTISELL, M. D. Hon. HORACE CAPRON, Commissioner,

THE FOOD AND HABITS OF BEETLES.

The following suggestions are submitted, partly from personal observation, and partly from the best authentic sources, both American and foreign, for the use of young entomologists, or persons who wish to study and identify the various beetles injurious or beneficial to vegetable and to animal substances.

The first part will contain the latest scientific name, as also the com. inon or vulgar appellation by which the insect is generally known, wherever it is possible to give it, with reference to some of the various authors who have described the insect, and a very brief history of its habits in the larva, pupa, or perfect state, together with the various vegetable or animal substances upon which it is found or feeds. Each insect, specially named, will be distinguished by a number in brackets, so as to be readily referred to by persons seeking information,

The second part will contain an alphabetical list of the plants and other substances upon which certain species of beetles feed, with the number in brackets before alluded to attached to it, as referring to the first part where the insects themselves are mentioned. The American works re. ferred to in this sketch are those of Dr. Leconte, of Say, Harris, Fitch, the “American Entomologist,” &c. The descriptions of the habits of thé various families are taken chiefly from Dr. Leconte, or Westwood, an English entomologist, who, in his valuable work on the - Classification of Insects,” gives the most lucid and brief descriptions, which will apply to the insects of the United States as well as to those of England, and in many cases throw much light upon the food and habits of many spe. cies in this country which have hitherto been unknown. The German work of Leunis also gives some very interesting details about the food and habits of several European insects, which also will be quoted. It is much to be regretted that many of our young entomologists merely col. lect, classify, and arrange insects in their cabinets for exhibition, without ever troubling themselves to ascertain anything about their previous existence as larva or pupa, or the plants upon which they feed when in the larva state, or the various transformations they undergo before they appear as perfect beetles. Were this subject made a more especial study, there is no doubt that farmers would learn much, and be better prepared to suggest methods of destroying them, than is the case at present.

PART I.

The first-family of coleoptera (beetles), Cicindelidæ, contains many species. These insects are generally of medium size, of swift motions, and frequently of bright metallic green, bronze, or brown colors, having their wing cases ornamented with cream-colored spots or stripes, from which, and their great voracity, they have derived the common name of tiger beetles. The larvæ are fleshy, curved grubs, of a yellowish white color, with large and powerful jaws, and hooks or spines on their backs. They burrow cylindrical holes in the ground, in which they lie in wait for any passing insect. They lie at the mouth of this burrow, having their head and thorax closing the opening, so as to be ready to seize any other in

sect, wbich, when caught, is immediately dragged to the bottom of their burrow, and devoured at leisure. The pupa is also formed in the same hole, and the perfect tiger beetle may be seen, any fine day in summer or autumn, flying on hot, sandy roads in the sunshine, but generally alighting again at a short distance, with its head turned toward the intruder, so as to be able to make another flight if necessary. As these tiger beetles, in both the larva and the perfect state, destroy all other insects they can overcome, they may be considered beneficial, and will be classed under the head of “ Predaceous" in the list of vegetable or animal substances destroyed by beetles. Cicindela vulgaris (1.) (Say, 2, pp. 422 and 522) is a very common species, and more is of a bronze color, with cream-colored marks on the point wing cases.

The second family, Carabidae, or ground beetles, vary very much in size, form, and color; their bodies are of a firm consistence, whereby they are enabled to creep under stones, bark, &c. Most of the species are eminently insectivorous, prowling about on the surface of the ground, under stones, or beneath the bark of trees or moss, in search of their prey, which consists of other insects. Some of the European species, however, are said to attack grain, and the larva of our Say native Omophron labiatum, (2) (Say, 2, p. 495), a small beetle of a

X black color, margined or bordered with a brownish yellow, is U said to be very destructive to young maize in the southern States.

2. 'One of our finest beetles of this family is Calosoma calidum, (3) Fab. (Say, 2, pp. 491 and 527). This insect is very con common in Maryland and Virginia, and the larva was taken in the act of devouring caterpillars of the common army worm (Leucania extranea, Guen), in an oat field, near Washington. Great numbers of the larvæ of the beetle were observed running about in the midst of the army worms, seizing and destroy. ing all that crossed their path; some of them were indeed so voracious as to become bloated with food, and almost unable to move. When this was the case, the full-fed and inactive gluttons almost invariably became the prey of their more meager and nimble brethren. The perfect beetle is of a dark coppery color, beauti. fully dotted with several rows of metallic golden spots on the wing cases. Calosoma scrutator (4) Fab. (Say, 2, p. 491) is much larger in size, and of a most beautiful metallic golden-green color; in the perfect state it also feeds upon caterpillars and insects, even ascending trees to obtain its favorite food. One of the family, Brachinus fumans, (5) (Say, 2, p. 439), is rather common under stones, and is mentioned here as having the singular habit, when either alarmed or irritated, of discharging from the posterior extremity of its body a caus: tic fluid; this discharge is remarkable for an audible detonation with its accompanying cloud of smoke as in the discharge of a gun; hence its common name of Bombardier beetle. West- i wood states that the vapor, which is of a very pungent odor, 5. is also emitted when chased by other insects, in order to enable it to escape from its enemies. The wing-cases of this beetle are of a dark color, whilst the head, thorax, and legs are of a yellow brown.

BY

[ocr errors]

..OOOOOOO Ooooooo

[ocr errors]

GO

The Lcbice constitute a sub-group, and are small, active bec. tles, some of the very beautifully marked. Many of this spe. cies are found on flowers. Numbers of the Lebia grandis, (6) ; small beetle with wing covers and also thorax blackishi, legs and

head of a yellowish or ochre color, were taken feeding on the 6. larvæ of the ten-lined spearman ( Doryphora 10-lineata), so inju. rious to the potato in the western States, in the month of July. Some of the tribe Pterostichini are stated, by European authors, to injure grain. Calathuslatus, (7)(Westwood, 1, p 63), a European insect, is said to injure young wheat. The larva of Zabrus gibbus,(8) also European, is said by Leunis to feed on the roots and shoots of grain, while the perfect beetle itself consumes the grain or seed of barley, wheat, and rye in Germany. Westwood, 1, p. 61, also mentions a similar fact; it would therefore be well for some of our entomologists to determine whether we have not some allied species in this country, injuring our grain crops. Some of the species of Amara (9) are also said to destroy grain in Europe.

Harpalus (Pangus) Caliginosus (10)(Say, 2, p. 454) is a me. dium sized beetle, of a brownish black color, which potentia diffuses a very pungent odor, like that of vinegar, when

disturbed; it has been taken in great numbers in Mary. land, under wheat stacks, and is commonly supposed by the farmers to feed upon the grain of wheat; it is probable, however, that these insects have collected together in such situations for shelter, or to feed upon other insects usually found in such situations. It must, however, be

confessed that this beetle has been taken under very suspicious circumstances in an open field on timothy grass stalks, appa. rently feeding on the seeds, when no other insect was visible to the naked eye, which might have been selected as its food.

Of the third family, Amphizoidæ, Dr. Leconte states that nothing is known about their habits.

The fourth family, Dytiscidæ, have the antennæ long and slender; their form is oval, elliptic, or rounded; and their hind legs are formed for swimming. These insects inhabit stagnant water, and are very voracious, feeding not only upon other aquatic insects, but also devouring fish-spawn or very small fish. Some of them occasionally fly by night from pond to pond, and are said to be attracted by a light.

One of the largest species, (11) Dytiscus hibri dus, (Lec.), was captured on the flat roof of a building in Maryland, at least four stories in height, where it had doubtless fallen during its nocturnal flight, and was unable to rise again. During the winter season the Dytiscidæ reinain in the water, or bury them- . selves in the mud, wliere some of them remain in a torpid state, while others retain their vitality and activity even under the ice.

The fifth fainily, Gyrinidæ, comprises those oval water-beetles usually known by the name of "wliirligigg” or apple-bugs; the former local name being

derived from their habit of swimming in large numbers in circles, or labyrinthine curves, on the surface of the water; and the latter name from the peculiar apple or calycanthus-like odor which they emit when taken in the hand. The European species deposits lier small, cylindrical eggs, which are placed end to end in parallel rows, upon the leaves of aquatic plants; the larvæ are said to hatch out in

about eight days, and to bear some resemblance to a young centipede. When they bave attained their full size, they creep out of the water, up the stems of rushes or other aquatic plants, where they inclose them. selves in oval cocoons, composed of a substance spun out of their own bodies, (Westwood, 1, p. 109). The perfect insect, if closely examined, presents the curious appearance of possessing four eyes, the organs of sigut being divided by the side of the head. These insects are predaceous, and feed upon insects on the surface of the water. One of our most common species, Dineutes (Gyrinus) Americanus, (12) (Say, 2, p. 519), may be seen at all times, excepting in winter, circling around on the still pools of water, feeding on living or dead insects which float upon the surface.

The perfect beetles of the sixth family, Hydrophilidæ, (13) live upon decomposing vegetable matter, although their larvæ are predaceous and quite voracious. The majority of them are aquatic, and are distinguished from other water-beetles by their clubformed antennæ; their bodies are usually of an oval form, and tho hinder legs are ciliated or fringed with bristles, and formed for swimming, or rather for paddling, in the majority. These insects do not swim with the agility of the Dytiscidæ, already mentioned; they generally keep in the water by day, but during the evening sometimes como abroad and take wing. The European species, Hydrophilus piceus, (13) feeds chiefly upon aquatic plants, although they also devour with avidity dead larvæ and aquatic molluscæ. The female spins a gummy envelope for her eggs, which amount to about fifty or sixty in number, and are disposed symmetrically in an upright position in their receptacle, which has somewhat the appearance of a small turnip, being nearly an inch broad, and which is attached to some plant until the larvæ are hatched, when it floats upon the surface of the water. The larvæ escape at the lower part of the cocoon, which is merely closed by a few threads. As larvæ they undergo three moultings, and feed upon aquatic mollusks and insects inbabiting the water.

Hydrophilus triangularis (14) (Say, 2, p. 128) is a rather common species, and is found in ponds and ditches; the insect is of a shining black color. The fifth tribe, Sphæridiidæ, (15) are terrestrial in their habits, of small size, and feed upon putrescent vegetable matter which has passed through the bodies of herbivorous animals, (excrement).

The seventh family, Silphidæ, (16) feed on carrion, dead fish, spails, &c., &c., and are in some degree beneficial, inasmuch as they remove from the surface of the earth animal matter in a state of putridity, which would otherwise taint the air and become injurious to health. They are constantly found in carrion and the carcasses of animals. Some of the European species frequent trees, where they probably devour caterpillars. Both larva and pupa of Silpha lærigata (10) of Europe reed voraciously on live snails. Some of the larger species are commonly called sexton or burying beetles, from their habit of burying the carcasses of small animals, birds, &c., for the purpose of depositing their eggs in the buried body, where the larvie, when latched, find a sufficiency of food until they become pupæ. These insects effect their purpose of burying small animals by undermining the carcass, until it gradually descends into the ground, and then covering it with earth. One of our best known species is the (17) Necropilorus marginatus, (Fab.), which may be found at any time during

14.

« AnteriorContinuar »