Hardly a season passes without my being in receipt of one or more
inquiries, personal or by letter, concerning this snowy brood which
haunts the alders in the swamp or along the road-side, and which
envelops the smaller branches in its dense, feathery fringe. It is
often one of the most frequent and conspicuous incidents in a country
walk during its season, and its season ranges from its height in early
summer until the frost. And yet how few there are, even of those,
perhaps, who pass it every day, who have any definite idea of its
character!
I know one rustic who claimed that it was "dry-rot," or a "speeshy of
mould"; but the woolly phenomenon is commonly dismissed by the rural
mind with the observation that it is "bugs of some sort." In this
case the haphazard verdict happens to be the literal truth, though the
speaker little suspects how closely he has discriminated. But his
present skill is easily accounted for when we remember that only
yesterday he had a great deal to say about "June-bugs" and
"lightning-bugs." He will tell you all about "lady-bugs," too, and
"rose-bugs," and "horn-bugs," and "pinch-bugs"--and has he not often
given his strong opinion on "potato-bugs"?--not one of which insects
is in the least entitled to the name of "bug." Only this very morning
he asked me if I was "as fond of goin' buggin' as I used to be." But
to the granger laity the entomologist is always a "bug-hunter," even
though no single species of a bug is to be found in his entire insect
cabinet.
What, then, is a bug, and why is the discrimination of "bugs of some
sort" so truly applicable to this brood with the snowy wool which
grows upon the alder twigs?
The term "bug" has almost become a popular synonym for "insect." All
bugs _are_ insects, 'tis true, but it by no means follows that all
insects are bugs. The "squash-bug" is almost the only insect that is
known by its true title in the popular vocabulary, for this disgusting
insect is in truth a typical bug.
But who would ever think of calling the whizzing harvest-fly a "bug?"
Rather will they persist that he is a "locust," which he is not. He
should be called the cicada. The "grasshopper" of the fields is the
true locust, whose swarms of certain species in the Orient have so
often shut out the sun, and whose voracious feeding has laid waste
whole square miles of vegetation in a single night.
But such a swarm of locusts as we read of in Scripture, and frequently
in the history of modern times and in our own country, would be
comparatively tame and merely amusing affairs were they composed of
our so-called "locust"--he of the whizzing timbrel in the sultry
August noon. For this insect has no teeth, and could not bite a blade
of grass if it wanted to. And herein we see one of the peculiarities
which constitute him a "bug," and which also includes in the same
company our woolly swarm upon the alder twigs. In place of teeth these
insects are supplied with a beak for sucking the juices of plants. If
we carefully examine the dense snowy mass we find it composed of small
tufts closely crowded together, each tuft being borne upon the plump
body of a small insect whose beak is deeply sunk into the tender bark.
I have separated one of the little creatures, and furnished his
portrait as he appears when viewed through a magnifying-glass, only
the lower portion of his body being covered with the wool, his head
and legs being usually concealed beneath the pluming growth of his
neighbors. This feathery growth seems of the most delicate
consistency--in truth, more suggestive of white "mould" than any other
natural substance, and seems to proceed from pores in the plump body
beneath it. The slightest breath wafts the cobwebby tips of the
fringe, and the least rude touch easily dislodges it, exposing the
round, naked body of what is now clearly seen to be an aphis, or
plant-louse, which nature, for some reason, has seen fit to clothe
with swan's-down.
In early June the white down first appears on the alders in tiny
patches here and there. This gradually extends down the stem, at
length, perhaps, completely encircling it, and thus remaining for
weeks, the full-grown aphis at last attaining a length of about
three-sixteenths of an inch.
A similar brood is sometimes seen in profusion on beech-trees and also
on the apple-tree. But if we imagine that because these insects are
without teeth they are therefore harmless, we are greatly mistaken.
What they lack in individual effect they fully compensate for in
numbers, and the combined attack of a girdle of thousands of these
sucking beaks, for weeks absorbing the sap, may often result in the
death of the branch beyond them.
Dr. Harris, in his admirable work on "Insects Injurious to
Vegetation," tells us that "in Gloucestershire, England, so many
apple-trees were destroyed by these lice in the year 1810 that the
making of cider had to be abandoned. So infested were many of the
trees that they seemed, at a short distance, as if they had been
white-washed."
Other insects, such as the flea and the mosquito, are also possessed
of similar "beaks for sucking," but neither of these examples is a
bug, both being _flies_--the flea merely a wingless fly with
wonderfully developed legs. Our entomology tells us that a bug is a
member of the _Hemiptera_, meaning "half-winged;" the wings of the
typical bug, like the squash-bug, being transparent for only about
half their length. But as in the flea among flies, here we find
myriads of true bugs without a vestige of wings, and others, like the
cicada, with ample wings as clear and free from opacity as those of a
fly. It would take more space than I have at disposal to tell
precisely what a bug really is entomologically, such a diversity of
forms is presented in the family. But the sucking beak, and the fact
that the average bug is _born_ a bug from the egg, instead of going
through the usual transformation of larva, chrysalis, and imago, will
have to suffice us for the present. Here, for instance, is the great
sub-tribe of the aphis, to which our woolly specimen belongs. What is
their life history? The eggs of the mother aphis are laid in the
autumn, giving birth to the baby swarm in the following spring. In an
almost incredible time they have multiplied to such an extent that the
twigs of our roses and many other plants are lost to view in the
encircling swarm. The secret of this wonderful arithmetical
progression may be seen in the following quotation, which applies to
aphides in general:
"The plant-louse of the apple-tree produces one hundred young ones in
a single generation, these being born alive, and each of these brings
forth others in equal number, until, at the end of the tenth
generation, which is reached before the coming of frost, the original
aphis has become the mother of one quintillion of her species."
But up to this time nearly all the aphides have been females; in the
last generation the winged males appear, and are seen assembled among
the swarm--the last mother brood laying the eggs which are to start
anew the cycle of life the following season.
So far as I have observed, however, the woolly species of aphis never
acquires wings, nature having in a measure compensated for their
absence in the growth of plumy down, which, according to Harris, is
so buoyant as to enable the insect to be borne upon the breeze from
tree to tree. To this resource he attributes the spread of the
wingless apple-lice species. But it would take a stiff breeze thus to
waft the body of our plump dweller on the alder, unless, indeed, in
his younger days.
"What Ails Him"
On a certain afternoon last August, having just completed a
particularly laborious work upon which I had long been engaged, and
with my mind naturally inclined towards relaxation in my plans for the
morrow's labors, my eye instinctively sought a certain note-book upon
my table. It was a note-book containing memoranda on a wide variety of
Nature topics, but presented in a particular place a choice, selected
list of topics under the title of "Young People." A large number of
these memoranda were crossed off with a pencil line, which told me
that these particular topics had already served their purpose, were
sufficiently elaborated in the columns of the "Young People," and were
now safely preserved between the covers of my book "Sharp Eyes."
But what an array of items were still left from the winnowing, which
had after all culled only a few of the best! Indeed, it was hard to
decide which should be selected as the subject for the morrow. Let's
see; shall it be those travelling underground buds of the Clintonia,
with all their leaves and flowers ready for next spring? No, I must
wait a little for these a month later and they will be more mature,
and I must make my drawing from nature. Then there is that queer blue
oil beetle, with his queerer history; that slender-waisted wasp that
digs its deep hole in the dirt, and those round holes in the path,
with their mysterious hocus-pocus.
Yes, it shall be these, the magic holes that disappear as you
cautiously look at them, or suddenly start into view as you
approach--deep holes, the diameter of a slate-pencil, with apparently
nothing in them, but which in reality have a good deal of mischief at
the bottom of them or at the top of them, as it happens. "Ant holes,"
most people call them. Many an ant, doubtless, goes into them, but not
because he wants to. "Yes," I thought, "my next chapter shall be
devoted to these queer holes and their shy tenants, which so few
people ever see or even dream of."
Having thus decided, I closed my note-book, but the experience of the
next few minutes quite reversed my plans, and led to the completion of
an entirely different article, or the pictures for it at least, on the
same afternoon, without awaiting the morrow.
I had barely closed the note-book when, chancing to glance out of my
studio window, I observed a well-known neighbor, a thrifty, retired
granger and carpenter, approaching across lots. His house stood out
against the sky at the crest of the slope, about a furlong distant,
above my studio, and he had perhaps reached half-way to my window
before I had observed him. Something in his walk, his somewhat
accelerated pace and evident preoccupied mood, as well as a peculiar
position of his extended right hand, foretold that some unusual errand
had turned his steps hitherward. With considerable curiosity I
endeavored to detect at a distance the specimen which he was bringing,
well knowing from experience that I should soon recognize an old
friend, which for sixty years had somehow managed to escape the notice
of its new discoverer.
Half across the meadow I now observed that he held a leaf in his
outstretched hand, and now I clearly noted that it was a compound
leaf, and in another second I knew it all. For was it not a leaf of
the Virginia-creeper or woodbine? and how many before him have
marvelled at that strange exhibition among the woodbine leaves which
had now probably met his eyes for the first time? In another moment he
was at the piazza stoop, and now he appears at the studio door. Eager
anticipation and shortness of breath were equally manifest as he
approached my easel and, with his right hand still outstretched
towards me, exclaimed, "Well, what ails _him_?" at the same time
laying down before me the mysterious specimen. It was a leaf of the
woodbine, bearing along its stem a cylindrical mass of what appeared
to be tiny, oblong, white eggs, all set on end, and so densely packed
that but for the head and tail of the shrunken, green caterpillar
which appeared at the two extremities of the mass no one would have
guessed their origin. "What ails him?"
"I was sitting on my porch," continued my puzzled visitor, "and saw
the white thing among the leaves, and took a closer look at it, and
found it was this. I never saw anything like it before, and I thought
perhaps you hadn't either, or, at least, that if you had you could
tell me something about it. What ails him, anyhow?"
The story was simply told, and my readers who have followed my
articles already know what the story is. We remember the strange
history of those little, puzzling cocoon clusters on a grass stem,
those "bewitched cocoons" which gave birth to swarms of tiny wasps
instead of moths, and we realize that here is more of the same sort of
mischief, all of which I explained to my good neighbor, to his
astonishment. How a few weeks since, when our caterpillar was much
smaller than now, a tiny, black midget hovered about him, and, in
spite of all his wriggling and squirming, stung him again and again,
each time inserting within his body its tiny eggs. Perhaps, and
probably in this case, from the number of the white tokens, more than
one of the flies took a turn at the unlucky victim, for he certainly
seems to have got more than his share.
"These eggs thus inserted beneath the skin of the caterpillar," I
explained, "soon hatched into minute white grubs, which immediately
fastened themselves upon the tissues within the caterpillar's body,
and he is now obliged to eat for the whole family, which he continues
to do without any outward signs of inconvenience or protest, which, of
course, would be useless. I fancy he must have frequent attacks of
that 'all-gone' feeling that we hear so much about in dyspeptic
people, but if he does he gives no hint of it by his looks, as he
devours one leaf after another along the stem, and displays his plump
proportions with evident pride--like the whole tribe of horny-tailed
'sphinx' caterpillars to which he belongs.
"But a few days ago he had a sudden and terrible experience. He had
begun to think of retiring down among the dried leaves on the ground
and spinning a cocoon, and there were bright visions of a future life
filling his little green head--visions of a life on wings, as quick as
thought, in an atmosphere of twilight and fragrance, and all manner of
sweet indulgences. But his beautiful dream was interrupted, and
probably will remain only as a dream. At one moment we see him in his
prime, a perfect specimen for the 'bug-hunter' who is after the larva
of _Choerocampa pampinatrix_. In ten minutes we look at him again:
we find his body shrunken and covered with minute white grubs, all
standing on their tails, which are still imbedded in his body; here
one barely emerged; here another half enshrouded in a gauzy cocoon;
others with their bodies bent into loops weaving the webby gauze
about them, while a few hours hence all are concealed, as we see them
now, in the completed long, oval, white cocoons which still remain
attached to his body."
"Well," remarked my listener, "I guess he feels pretty sick; if he
don't, I vow I feel sick for him. I knew something awful ailed him,
but didn't know what. I thought the things were eggs. What's the good
of it all, anyhow? What do the cocoons turn into?"
I have wished more than once that my friend could have been in my
studio the day following his visit, in order to have witnessed the
ocular answer to his last question. It was evident that his
caterpillar specimen might have been discovered with its load of
cocoons a fortnight ago, for in the morning, upon opening the box in
which I had placed him, a number of tiny black flies flew out, and
several of the white cocoons were open at the end, their dainty hinged
lids thrown back. Here is one with its black midge just creeping out;
others with the tiny imp peeping through the fine crevice; others with
the lid still tightly closed, but with its juncture disclosing more
distinctly every moment the knavery of the busy teeth within. One by
one the silken lids popped up, and out flew the mischievous
jack-in-the-box until within the space of a few hours every cocoon was
empty. So this is "what ailed him." He has been the victim of the
parasitic fly known as _microgaster_.
But even now that his mortal enemies have left him, I fancy he is past
encouragement or salvation. What will become of him? In his particular
case he continued to dwindle and soon died, though in other instances
I have known him to recover and reach the chrysalis stage, to complete
his transformation into a beautiful olive and red sphinx-moth.