This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
The fall exhibition of the Brooklyn Horti-cultural Society will be held at the Academy of Music on Tuesday, Wednesday, and Thursday, September 23d, 34th, and 25th. The audience room will be used on this occasion; and when floored, as it will be, it makes an admirable room for an exhibition. We hope the members of the Society, and others, will make a de- termined effort, and eclipse all former exhibitions. Circulars may be had of the Secretary, C B. Miller, 634 Broadway, New York.
The last Conversational Meeting was held at the Academy of Music, President Degrauw in the Chair. The evening was mainly occupied with Dr. Trimble's Report on Insects injurious to city trees, from which we make the following extracts, to be followed by others.
In the Report of your Committee on this subject, it is stated, three of these parasite flies had been long known. In these investigations I have found eleven varieties, varying in size from a small wasp to others, such mere specks as to require the aid of a glass to be able to distinguish the characteristics of the Ichneumon class. More or less of these have been found in every part of your city as well as in New York. In a collection of thirty of the worms in the pupa state taken from one tree, fifteen had been destroyed by these enemies, and in these fifteen, there were five varieties of these parasites. But from no other tree or section of either city have I found the proportion of these enemies, or friends rather, so great.
At the last meeting I spoke of one tree near your public buildings as having been a subject of special attention; that the number of worms on that tree in the be. ginning of the season was unusually great; that two weeks later not one could be found upon it, and that the ground was almost covered with the dead bodies of half-grown caterpillars.
The chairman of your committee had observed the same thing, and supposed that the leaves of the tree (a variety of the Elm) were poisonous to the worms. This was a very natural inference; but if poisonous this year, why not other years? And why should the parent moth have chosen a poisonous tree to deposit her eggs upon?
In the world of wonders in which we live, there is nothing more wonderful than the instinct of insects; it is almost never at fault. You may find small collections of eggs upon the Ailantus and some other kinds of trees that these worms do not prefer to feed upon, but it must be remembered that the laying of the eggs with insects is usually the last act of life, and that often they become almost too feeble to fly; in this condition they may be sometimes carried by the wind, during storms, to other trees that would not be their choice. But it would be hard to find an instance where a parent butterfly has left her progeny to the contingencies of poisonous food. My investigations were commenced too late to ascertain positively that these young worms had been stung by parasite flies; but I suppose they were, from the circumstance that I have in many instances found the larva of insects in the bodies of these caterpillars; that they differ from the eleven specimens found in the pupae in this important particular, that when full grown, they leave the bodies of these dead caterpillars, and pass into the ground, and to all appearance thus far will not undergo their transformation into flies till next season.
Now, if this theory should prove correct, and these flies multiply at the rate such insects usually do, another year they may cause a greatly increased number of your young worms to come to the ground prematurely; and if you should offer a bounty on worms, this very kind would be likely to be brought in; and should they then be so disposed of as to destroy also the embryo parasites within them, you would find yourself about in the predicament of the man who killed the goose that laid the golden eggs. * * * *
It may be asked, what has all this talk about Parasite or Ichneumon flies to do with the great question in Brooklyn, "What shall be done with the worms?"
At one time, many years ago, the whole civilized world was asking, "What shall be done with the Hessian fly?" And thus went on for a series of years, until wheat was likely to come up to starvation prices. But during all this time a little Ichneumon fly was mustering its forces, increasing them rapidly every year, until at length in overwhelming force it pounced upon this destroyer, and that question has been settled ever since.
I have lately seen a statement from a western agricultural paper, of four different parasites found for the caterpillar called the Army worm. That strange insect appears occasionally as the plagues did in Bible times. In the prophet Joel there are several allusions to these insect visitations. Of one of them it is said, "The land is as the garden of Eden before them, and behind them a desolate wilderness; yea, and nothing shall escape".
So with this army worm. When a universal destruction seems impending, and men begin to realize how helpless they are to avert it, the laws by which God has decreed that the insects, as well as every other portion of his creation, shall be governed and controlled, are found to be enforced, and in good time.
This parasite or Ichneumon class of flies is one of his instrumentalities. * * *
We continue the proceedings of the Conversational Meetings. The following is the remainder of Dr. Trimble's report on Insects injurious to City Trees.