4,36 
AMERICAN AGRICULTURIST. 
[November, 
eeen hoveling over the ponds where there are water- 
snakes. On the continent of Europe they have more 
pleasing names. In France, they are Demoiselles, or “ la¬ 
dies,” and in Germany Wasserjungfern, or “ Virgins of 
the Water.” In traveling in the Southern States, I had 
heard them often called “Mosquito Hawks,” and was 
told that they devoured so many mosquitoes that it was 
censidered wrong to kill one of them. At last I had an 
opportunity to learn that, for once, a popular notion was 
correct. One excessively hot day in June, I happened to 
placed. If you put them in an aquarium, there will after 
a while be little else left, at least of the smaller inhabi¬ 
tants, for they attack creatures much larger than them¬ 
selves. It is difficult to say which is the most curious in 
the “ Water-tiger,” (which is a convenient and shorter 
name for the Dragon-fly larva), its head or its tail. Curi¬ 
ously enough, the creature breathes through its tail! You 
no doubt know that fishes breathe through gills placed 
in the head, and as the water flows over these, they take 
up the air that is dissolved in the water, and thus carry 
remaining apparently lifeless for some time, and at length 
break their enclosing shell or skin, and come out a per¬ 
fect butterfly, moth, or beetle. But the Dragon-flies are 
quite too busy to keep still, and even in the pupal state 
are as lively and greedy as ever. They change their skin, 
and show by a hump, where their future wings will be, 
and the eyes of the perfect insect may be seen under the 
skin, but as to keeping quiet, it doesn’t know how. At 
last its time comes, and the pupa crawls up the stem of 
some plant, and leaves the water forever. Instead of 
THE LIFE HISTORY OF THE DRAGON-FLIES ILLUSTRATED. 
be on Lake Ponchartrain, not far from New Orleans; 
there were several pleasure houses, to which the people 
came from the city in the cool of the evening for a drive, 
and for ice-cream and other refreshments. These places 
were mere sheds, or shelters, and on the inside of them 
were mosquitoes by the million, resting in the heat of the 
day, to be all fresh to receive the evening visitors. I 
never before, or since, saw so many mosquitoes, for they 
were so thick as to make the sides of the building look 
gray. There were also hundreds of Dragon-flies—good, 
big fellows—which flitted about and fed upon the mos¬ 
quitoes at such a rate, that I saw at once that they were 
well named “ Mosquito Hawks.” When we see these in¬ 
sects so busy darting here and there, they are no doubt 
hunting for mosquitoes and other insects upon which 
they feed. The engraving shows one of the Dragon-flies 
on the wing, and gives an idea of the general appearance 
of all, though many are much smaller in the body, and in 
spread of their wings. But the early life of the insect is 
quite as interesting as that of its perfect or winged state. 
The female insect places her eggs upon the stems of wa¬ 
ter plants, just at, or below the surface, and from these 
hatch out the larvcex or the first form of the insect. The 
larvae of the butterflies and moths we know as caterpillars, 
and that they live on plants on the land, but the larvae of 
some insects, including the mosquitoes and Dragon-flies, 
live entirely in the water until they are ready to change 
into perfect insects. The larva of the Dragon-flies is 
sometimes called the “Water Tiger,” and well deserves 
that name, for it is one of the most voracious of living 
creatures. The insect in the water at the lower part of 
the engraving—the one directly in the center—shows the 
larva as it usually appears. These “'Water Tigers ” may 
be found in pools and muddy ponds, and in still places 
along the margins of rivers, and, though not handsome to 
look at, they are very interesting to watch. If you wish 
to study their ways, you can easily catch them with a 
small net, and put them in an aquarium, or what is bet¬ 
ter, a jar by themselves, in which some water plants are 
on a slow kind of breathing. But in the “ Water-tiger ” 
its gills are placed near its tail; it takes in water there 
through an opening, and forces it out again, and that is 
its way of breathing. But this opening answers another 
purpose. The animal crawls quite slowly, and as it is a 
great feeder, it would not get much food, did it depend 
solely upon its legs. If you watch one of them in search 
of food, you will be surprised to see the sluggish fellow 
dart for its prey with the greatest speed, and this motion 
is one of the many strange things about the creature. 
Ordinarily the water passes out of the opening in the tail 
quite slowly, but when necessary, the insect can force the 
water out with a sudden squirt, and that pushes it 
along through the water with great swiftness, upon the 
same principle that a rocket is sent through the air. Not 
less curious are the arrangements at the other end of the 
insect—at the head. As usually seen, it appears as in the 
figure at the middle of the lower part of the engraving, a 
quiet and rather harmless loeking larva. But let a small 
insector other animal come within reach, and, presto, 
the mild looking fellow shows a savage pair of pincers, 
and becomes the very tiger-ish animal seen in the right- 
hand lower corner of the engraving. This arrangement 
for taking its prey is called a “ mask,” and when not in 
use, is bent down under the head of the insect, and quite 
out of sight; it is so arranged that whatever is caught by 
the jaws of this mask, is brought, wlien that is folded 
under, right opposite to the true mouth of the insect, 
where it can be eaten. These Water-tigers not only 
prey upon other water insects, but even devour small, 
fishes, and seem to live only to destroy and eat other 
living things. They go on feeding and growing, some 
one year, and some, it is said, for two years, when 
the time comes for them to change to perfect insects 
—to leave the water, and begin a new life in the 
air. You know that when caterpillars and most other 
insects—as I have shown you on several occasions 
—make this change, they go into the pupal state, and 
either spin a cocoon, or form a chrysalis in some way, 
breathing the water through its tail, it now has to breathe 
air through openings in its sides, and instead of propel¬ 
ling itself, rocket-like, through the water, it has to dart 
through the air, and for this it must have wings. All 
these are provided. The pupal skin at last bursts, and 
the perfect Dragon-fly slowly pulls itself out, as you see 
at the left hand of the engraving. At first the wings are 
damp, limp, and useless, but they gradually spread and 
dry—and what beautiful wings they are 1 They are worth 
a close examination; see the delicate frame-work, so cu¬ 
riously netted, with a beautiful membrane filling the 
spaces between ; this is wonderfully thin and transparent, 
and the light often plays on it with rainbow colors. Can 
anything be more complete than this transformation— 
from an ugly inhabitant of muddy water, to a light and 
graceful creature of the air 1 But there is one thing which 
the Dragon-fly does not leave behind him with the re¬ 
mains of its former life—he has his appetite, and skims 
away through the air, devouring other insects, quite as 
effectively, as it did before as a “ Water-tiger.” There is 
one thing about the perfect insect, you will not fail to 
notice—that is the great eyes, or rather masses of eyes, 
as the microscope shows them to be ; these, while the 
insect is alive, have beautiful colors ; besides these, 
there are three little single eyes, usually placed in a row 
on the front of the head. So far from the Dragon-flies 
being dangerous, we may look upon them as not only 
harmless, but so far as they destroy mosquitoes, as real¬ 
ly beneficial insects—at any rate, I hope that I have 
shown you that they are really interesting ones. I have 
said nothing about the scientific names of these insects, 
their being several different genera, or kinds, and only 
those who study entomology, will care to know the sys¬ 
tematic names, but it is well to know that these belong 
to the division or sub-order Neuroptera , which means 
nerved-winged, and includes, besides the Dragon-flies, 
the May-flies, the Lace-wings, and besides other?., the 
Caddis-flies, one of which I told you about, as the insect 
that builds a stone-house. Thk Doctor. 
