July 10, 1884] 



NA TURE 



2 4; 



destroyed every green thing. The plague lasted for 

 weeks, and until the insects obtained wings, when the 

 winds soon after wafted them away to devastate the lower 

 country, and the ocean received them. Any opposition 

 seemed so hopeless that none was attempted." 



Among the most terrible of the insect scourges which 

 affect the vast territories of the Western World, is the 

 army-worm. The name arouses old associations, and 

 one involuntarily recalls " the canker-worm, and the cater- 

 pillar, and the palmer-worm, my great army which I send 

 among you." The army-worm well deserves his name, 

 although like most familiar vernacular appellations it may- 

 have been wrongly employed. The cotton-worm (Aletia 

 xylind), for example, has been so designated ; but the 

 true army-worm is Leucania uniptauta, known in the 

 earlier chronicle as the " black worm," and is the larva 

 of a Noctuid moth, named as above by Haworth. It is 

 difficult to give an idea of the fearful character of this 

 plague when in obedience to solar influence it begins its 

 march. " Almost with a shudder (p. 145) one remembers 

 that terrible invasion of Monmouth, when the potato 

 fields were ruined as if by fire, and the waggon wheels 

 reeked with greendripping gore as they entered our villages. 

 . . . That .beautiful lawn of Hollywood at Long Branch 

 was invaded by them. The emerald sward was swept 

 as if burnt. When any of the worms came against a tree 

 they went up it, passed over the crotch, then descended 

 at the other side. There is no 'turn back' to this singular 

 worm, and when their path is intercepted by a stream, on 

 they come, until, crowded forward, a compacted mass is 

 urged into the water to serve as a living pontoon, over which 

 the army passes to take possession of pastures new." 



Another account states that the army-worm when 

 travelling will scarcely turn aside for anything but water, 

 and even shallow water-courses will not always change 

 its progress. They avoid the rays of the sun, hence during 

 the day they crawl under stones and sticks as closely as 

 they can crowd themselves together, like the cut-worm. 

 They come out towards sunset and continue their mighty 

 march. If they come to a field of grass or young grain 

 they devour the whole of it, down to the very roots ; but 

 if it is grown up to stalks they eat the leaves only, and 

 then usually crawl to the top of the stalk and cut off the 

 head and drop it to the ground. 



They all keep together like an army of soldiers, and 

 usually advance in a siraight line, not swerving from their 

 course to avoid hills, hollows, buildings, or any other 

 obstacle. On coming to a brook, they crowd into it ; 

 millions of them are drowned, their dead bodies clogging 

 and damming up the stream in places below, producing 

 by their decay a stench in the atmosphere of the whole 

 vicinity most noisome and intolerable. 



Monmouth County was invaded in 18S0, and the 

 following graphic sentences from the New York Sun will 

 help us to obtain an idea of this calamity : — 



" Trenches were seen extending for miles along the 

 roads close to the edges of the fields, but the crops for the 

 most part were withered and lifeless, and it was evident 

 that the precautions had been taken too late. Very often 

 a trench ran across a wheat-field, showing where the 

 farmer had abandoned one portion of his crops and tried 

 to save the remainder. Occasionally a field was seen 

 intersected by numerous trenches, indicating that the pro- 

 prietor had fought manfully against his persecutors, and 

 disputed the ground with them foot by foot. In many 

 places the road was literally covered with the worms, all 

 in motion, and all moving towards the fields on either 

 side. Thousands and tens of thousands were crushed 

 beneath the waggon wheels and under the horses' feet, 

 but the rest passed on. And at intervals spots were passed 

 where an imaginary line seemed to be drawn across the 

 road beyond which the army-worms could not pass. 

 For a certain space beyond, sometimes for a distance of 

 two or three miles, not only the roads, but the adjoining 



country was free from the pest. Not a worm was to be 

 seen until, the clear space passed, the waggon was again 

 rolling over millions of them." The remedies suggested 

 partake of the general character of the means proposed 

 by entomologists, and are probably mostly learnt by the 

 entomologists from the farmers and peasants. They con- 

 sist in rolling, fencing, ditching, burning, coal-tarring, 

 poisoning, "drawing the rope," which is done by two 

 men drawing the rope in a direction at right angles to its 

 own length. 



Another pest of different habits and less widespread 

 destructiveness is the Canker-worm {Anisopteryx pome- 

 taria and a-sailaria), an insect which feeds on the leaves 

 of apple-trees, and completely ruins orchards. Ento- 

 mological science has conferred a boon by suggesting 

 methods of getting rid of this creature by taking ad- 

 vantage of its peculiarities. The female, like our glow- 

 worm, is wingless, and therefore cannot rapidly spread 

 beyond the locality where it exists. She hibernates in 

 the earth near the roots of trees, and on the first return of 

 spring she ascends the trunk, depositing her eggs between 

 the leaflets of the expanding buds, sometimes even close 

 to the ground, but oftenest under loose scales of bark. It 

 is this peculiarity of the female which enables the fruit- 

 grower to grapple with the difficulty. One of the best 

 means is what is known as "hanging the band." This 

 contrivance consists essentially of a band or ring of tin 

 a few inches outside the trunk of the tree, and held there 

 by a circle of muslin attached to the tin at its edge, and 

 drawn with a cord at the top, so as to fit the tree closely 

 and prevent the insects from going over the tin, which is 

 coated with a mixture of castor-oil and kerosene : as soon 

 as they touch this they drop to the ground. Troughs of 

 oil arranged closely around the tree, or the complete 

 isolation of the tree by fitted boarding lined on the out- 

 side by smooth tin and also fitted with shallow troughs 

 for oil are also used. Another ingenious plan is to use a 

 cylinder of sheet tin upon a band of line or cord. The 

 cord forms a firm boss around the tree, and the hollow 

 cylinder surrounds it and extends them at four inches 

 above and below it. The female finds this an effective 

 barrier, and it is said if she even succeeds in passing up- 

 wards to the top of the cylinder she will never descend in 

 the inside so as to again reach the tree. 



A good deal of interesting evidence is adduced upon 

 the effects of " jarring and burning," or the jarring of the 

 affected trees, after spreading a light coating of dry straw 

 on the ground below, which is then fired without injury 

 to the trees. A table-spoonful of Paris-green in twelve 

 quarts of water applied to the tree with a large syringe, 

 when, as nearly as can be judged, the worms are all 

 hatched, is a second method. " Fall-ploughing" is a 

 third plan, which appears to have been very successful ; 

 and, lastly, attention has been very properly drawn to the 

 balance of power in nature by encouraging birds and 

 parasitic insects that live upon the canker-worm. A 

 valuable distinction has also been pointed out by the 

 Commission between the "fall" canker-worm, and the 

 spring species, from which it differs in many important 

 respects, as ma} - be gathered from its name. There are 

 many other interesting chapters in the volume which we 

 should have liked to at least have mentioned, but it is not 

 our object to do more than give a good general idea as 

 to the work of the Commission and the manner in which 

 it is prosecuted. We therefore leave the consideration of 

 the Hessian fly and the Rocky Mountain cricket, with a 

 hearty recommendation to those who are interested in 

 economic entomology to obtain this Report. J. W. 



THE FORESTRY EXHIBITION 



IN last week's Nature (p. 222) we briefly noticed the 

 remarks of the Marquess of Lothian in declaring the 

 International Forestry Exhibition at Edinburgh open. For 



