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examined, as would also the people of Texas and California against plants from Mexico. We shall, as soon as the most favorable opportunity offers, endeavor to colonize the Vedalia on the infested plants of Key West.
EXPERIMENTS AGAINST THE BLACK SCALE.
(Lecanium olece Bernard.)
[Plate VII, Fig. 1.] The so-called black scale (Lecanium olece) has for a number of years been a somewhat serious pest in certain of the California orange and lemon groves. Originally a foe to the olive, it has spread to various other trees and is found commonly on the oleander, peach, and apricot, as well as upon citrus trees. It secretes a large amount of honey dew, and is hence followed by a greater abundance of the smut fungus (Fumago salicina) than are any of the other commoner scales. It is an extremely prolific species, although probably having but one annual generation, and would doubtless become a scourge were it not for the fact that it is extensively parasitized by Dilophogaster californica, a Chalcid fly which breeds rapidly and is at times very abundant. In 1880 Professor Comstock found that at least 75 per cent of the black scales upon more than one tree in the vicinity of Los Angeles had been destroyed by this parasite, while in 1889 Mr. Coquillett reported an almost equal destruction of the scales from the same cause. A curious fact is that while the Black Scale is directly or indirectly of European origin, the parasite evidently belongs to the Australian fauna, nothing like it being known to occur in Europe.
Californians as yet have done little in overcoming this specific scale, their attention having been so largely occupied with the more important fluted scale (Icerya purchasi) and red scale (Aonidia aurantii). With the disappearance of the former, however, through the work of the Cardinal Vedalia, and the recent success and great reduction in the cost of the gas treatment of the black scale, the San José scale (Aspidiotus perniciosus), the flat or soft scale (Lecanium hesperidum), and others of less prominence will doubtless receive more attention,
Mr. Ellwood Cooper, of Santa Barbara, has probably paid more attention to the matter of remedies for the black scale than any other California horticulturist, and after somewhat extensive experiments with the caustic washes and whale oil soap and other substances such as hot tobacco water, has finally fallen back upon the substance which we should have first recommended, viz, kerosene emulsion, which he applies hot and makes in the following manner:
Fire gallons best kerosene oil, 150° test; 17 pounds good common soap or one bar and a half of soap usually sold as pound packages; 2. galions of water. This makes the emulsion. When using dilute 6ļ to i gallons of water for each gallon of oil and to this mixtureadd 2 } pounds of good home-made soap dissolved in boiling water. All this mixing is done with hot water. We usually have the solution up to 140° in the tank from which we spray:*
Our attention was called to the desirability of further experiments last September by Prof. W. A. Henry, director of the Wisconsin Agricultural Experiment Station, and at his suggestion we sent Mr. Coquillett to Chula Vista, California, for the purpose of making a trial of a modification of the Nixon pump, invented by Mr. E. S. Goff, of the Wisconsin Station, whereby kerosene is drawn from one vessel, water from another, and the two mingled in the chamber of the pump and thrown from the nozzle, in Professor Henry's words “as a very fine emulsion.” The object of the modification was to do away with the trouble and expense of keeping the kerosene properly suspended in the water. We were glad to have an opportunity to test the modification, although realizing that a mixture made in this way would not be an emulsion proper. We therefore instructed Mr. Coquillett to conduct certain experiments on the black scale at Chula Vista with this machine and to check them by a series of tests with a carefully prepared emulsion.
* Biennial report of the State Boaru of Horticulture, 1885–'86, Sacramento, 1887,
The results can be best presented in Mr. Coquillett's owń words, as follows:
The inclosed figure illustrates the pump in question, and I have added in pencil a sketch of the attachment to this pump as first used by Professor Goff, of the Wisconsin Experiment Station. In spraying kerosene upon the tree the water or soapsuds is drawn up by the larger hose and the kerosene by the small tube attachment, the two being drawn up by the same operation of the pump, mingled together and sprayed upon the trees. There is a stopcock in the upper part of the tube attachment by means of which the quantity of kerosene drawn up by the pump may be regulated.
I tested this pump by using soapsuds and kerosene according to your formula, one-half pound of hard soap dissolved in hot water, then diluted to make 28 gallons, to be used with 2 gallons of kerosene. After adjusting the pump so that it would draw up 2 gallons through the tube attachment at the same time that it would draw up 28 gallons through the large hose, I sprayed several trees with the above mix. ture and also sprayed some of it into a boitle in order to ascertain how long it would take for the kerosene to separate; it produced a whitish emulsion similar in appearance although a shade lighter in color than that made in the ordinary way. The oil remained in suspension for three or four hours. On the morning of the third day nearly all of the oil had separated out, forming a layer of pure oil over the surface of the soapsuds. I also made an emulsion of the above ingredients in the ordinary way, dissolving the soap in 1 gallon of water by boiling, and while hot added the kerosene and pumped this back into the same vessel again through the spraying nozzle, continuing this for about five minutes; this formed a thick, creamy substance which diluted perfectly with water, and I added water to it until the whole measured 30 gallons.
Some of this I sprayed into a bottle as I had done with the previous emulsion, and on the morning of the third day only one third of the oil had separated out. It thus appears that when the kerosene and soapsuds are drawn up separately by means of the tube attachment, the emulsion formed is only one third as stable as that made in the ordinary way. Whether or not this will make any difference with the effect of the kerosene on the trees and insects sprayed with it can not be determined at the present time, as it will require several weeks for the kerosene to exercise its full effects upon the trees and insects. I also used pure water in place of the soapsuds, but after remaining quiet in the bottle that I sprayed some of it into, all of the keroosene separated out at the end of about three minutes. I have sprayed several trees with each of the three emulsions mentioned above, and will note the comparative etfects of each and report to you later on.—[September 24, 1890.
I have just returned from Chula Vista, where I went to ascertain how my experiments with Professor Henry's pump turned out. At my previous visit, September 20, I applied the kerosene according to Hubbard's formula (kerosene, 64 gallons; hard soap, 19 pounds, and water enough to make 100 gallons), both by making an emulsion of it and also by emulsifying it at the time of spraying it upon the trees with Professor Henry's pump, but I was unable to see any diiference in the effects. In neither instance were the trees injured, nor were the Lecanium olece and hesperidum exterminated. The trees operated upon were less than 5 feet tall and were lemons and olives. I sprayel one of the olive trees with the above emulsion, emulsified in the usual manner, with a solution of arsenic and bicarbonate of soda added, 1 pound of each to 864 gallons of the emulsion, but thus did not prove fatal to the Lecanium oleve sprayed with itI also used the emulsion about one third stronger than above indicated (kerosene, 10 gallons; soap. 1. pounds; water enough to make 100 gallons), and spraved it upon one olive and three lemon trees with Professor Henry's pump; the lemon trees were not injured but several leaves at the tips of some of the branches on the olive trees were killed; but the Lecanium oleo and hesperidum vere not all of them destroyed by the wash. At the above proportions, each gallon of this emulsion would cost about 2 cents.
These experiments lead me to believe that the effect of the emulsion is essentially the same whether it is first emulsifie l in the ordinary way or by the use of the pump sent by Professor Henry. At the time of making the above tests I also tried the resin wash according to the formula given in my last year's report to you (resin, 18 pounds; caustic soda, 5 pounds; fish oil, 21 pints, and water enough to make 100 gallons); this I sprayed on an olive tree and two orange trees; neither of the trees were injured by the wash; on the olive I found only one living Lecanium oleæ, but on the orange trees neither myself nor Jr. Adams, Professor Henry's foreman, were able to find a living Lecanium hesperidum. This wash costs less than 1 cent per gallon.—[October 28, 1890.
THE GREEN-STRIPED MAPLE WORM.
(Anisota rubicunda Fabr.)
[Plate V, fig. 3 ; Plate VI.]
Our attention is drawn from time to time to the ravages of the larvæ of Anisota rubicunda on soft maple trees, particularly in the central Western States. These deprecations are the more noticeable and serious on account of the importance of the swamp or soft maple in all forest and ornamental plantings in the West, where it is one of the favorite trees on account of its rapid growth and the minimum of care and attention needed in its propagation. The sole drawback is the liability of its being defoliated once or twice yearly by the larva under consideration, and this has led, in frequent instances, to the replacing of these trees by other and perhaps less desirable varieties. This course is entirely unnecessary, as the maple can be easily protected by the application at suitable times of either of the common arsenical poisons, Paris green or London purple.
A very characteristic onslaught of the green-striped maple-worm has been experienced the past summer at Lincoln, Nebraska, and seems to have been left to run its course unchecked. We give, as of interest in this connection, a view of the main building of the State University with a row of large maple trees in front defoliated by this insect. This illustration is reproduced from a photograph obtained in July last for us by Mr. Lawrence Bruner, and indicates at once the thoroughness with which maples are sometimes stripped by these larvæ and the neglect by the proper authorities in this instance of all measures against them. We have seen similar complete defoliation in years gone by on the grounds of the State Agricultural College at Manhattan, Kansas, and on those of the State University at Lawrence. The frequent recurrence of this insect will warrant the reproduction, in the main from our Fifth Report on the Insects of Missouri, of a brief account of its range, life history, and the preventive and remedial measures to be employed against it.
RANGE AND LIFE-HISTORY,
While especially abundarí in the West, this insect has a wide range, extending through the Eastern States and Ontario. It has been observed as far east as Brunswick, Maine, by Dr. Packard, and in the District of Columbia it not infrequently occurs in great numbers and attacks both the swamp and silver maples. In the West it is reported more frequently from Illinois, Missouri, Iowa, Ne. braska, and Kansas, in most of which States the soft maple is indigenous, a fact which accounts for the excessive multiplication of the insect there as compared with the more eastern sections of the country.
It feeds on other maples and presumably on all species of the genus Acer, and when forced to from necessity will feed on oak, though normally never found on that genus of trees, and probably incapable of full development thereon.
The eggs are deposited by the parent moth in batches of thirty and upward on the under side of leaves. The number matured by a single moth is large, in one instance 145 eggs were laid by a moth in captivity and in another 102 eggs were laid. The insect died in the latter instance before oviposition was completed, as examination revealed many more eggs still in her abdomen. The egg is about 0.05 of an inch long, suboval, slightly flattened, pale greenish, becoming yellowish and showing the black head of the inclosed larva just before hatching, and is hatched in eight or nine days after being deposited. The larvæ undergo four molts and reach full growth in about a month, when they enter the ground and transform to pupæ.
The worms (Fig. 3 a) are longitudinally striped with pale and dark green lines, and are chiefly distinguished by two anterior projecting black horns on the top of the second segment, and by having segments 10 and 11 a little dilated and rose-colored at the sides.
The pupa (Fig. 3 b) is of a deep brown or black color, very much roughened and armed with curved horns and points about the anterior extremity and also on the last joint, which terminates in a long bifurcate projection. The pupæ of the first brood give forth the perfect insect in fourteen to sixteen days, those of the second brood usually wintering over in the ground. In the West there are usually but two broods in the year, but experiments here in the District indi. cate that three broods are occasionally produced.
The pupa, before giving out the imago, works its way to the surface by the aid of its spines, allowing the ready escape of the moth. The moth is of a pale yellowish color shaded with pink, as in the figure (c) which represents the female. The male has a smaller abdomen and broad bipectinate antennæ. Different specimens vary greatly--the yellow predominating in Western and the rose-color in Eastern specimens, while others again, especially from the West, are nearly or quite white in color—this form having been unnecessarily described as a new species by Mr. A. R. Grote.
We mentioned in the Missouri report cited a number of insect parasites, and we believe the list has not been added to by subsequent writers. These are: Tachina anonyma Riley, Belvosia bifasciata Fabr., Limneria fugitiva Say. We have in our notes, however, the record of the breeding of an egg parasite, probably either a Telenomus or a Trichogramma, by Jr. William Saunders. These parasitic insects very effectually aid in the control of the worm, which in fact seldom occurs two years in succession in injurious numbers,