7o 



THE HUMMING BIRD. 



[September i, i8gi 



been most frequently enquired about by my corres- 

 pondents during the last two seasons. Where pos- 

 sible, illustrations are given, so that those concerned 

 may not only know the latest remedies, but at the 

 same time may become familiar with the appearance 

 of their enemies. 



^Economic Entomology is the name given to a 

 special study of the habits of Insects with the view of 

 finding out and protecting such as are beneficial, and 

 of destroying those which are injurious. 



As year by year larger areas of land are brought 

 under cultivation the various injurious insects which 

 attack special crops will become more and more 

 numerous as the cultivation of their favourite food- 

 plant is extended. It is estimated that there is no 

 crop grown which is not diminished by an average of 

 at least one-tenth, by the depredations of insect 

 enemies, and this loss in some years runs up to one- 

 fourth or one-half of the whole crop. Of this loss 

 there is no doubt that a large proportion can be saved 

 by the adoption of simple methods founded on 

 general principles, with which all can easily become 

 acquainted. For the effective use of remedies to 

 destroy injurious insects a certain amount of know- 

 ledge of their structure and habits is highly desirable, 

 so that the most appropriate remedy may be adopted, 

 and also that it may be used at the period when the 

 enemy is most susceptible to injury. 

 |jjj$The lives of insects are divided into four well 

 marked periods. These are: — i. The egg; 2. The 

 caterpillar or larval stage, during which, as a rule, they 

 are most injurious ; 3. The pupa or quiescent stage, 

 in which, except in a few orders, they lie quiet, and 

 are without the power of motion ; and 4. The perfect 

 Insect. Some insects are injurious in three of their 

 stages ; but the larger number in one only, so that 

 unless we try to know them in all their forms we may 

 lose the best opportunities ot destroying them. It is 

 clear that in this warfare the one who possesses this 

 information has a great advantage over those who do 

 not. 



Insects may be divided into two classes by the 

 nature of their mouth parts. In the first or larger 

 division, Biting Insects, they are furnished with man- 

 dibles or biting jaws, by means of which they consume 

 the substance of their food, as with caterpillars, 

 beetles, etc. In the second class, Sucking Insects, 

 they have instead of mandibles a beak or tube, by 

 means of which they suck up their food in a liquid 

 form from beneath the surface, as with the true bugs, 

 plant-lice and flies. It is evident that with the insects 

 )f the first class all that is necessary is to place some 

 oisonous substance on the food-plant, which they 

 ill eat together with their food. With the second 

 [ass, however, this would be useless, for they would 

 ush their beaks through the poisonous covering on 

 ie outside of their food-plant, and would extract the 

 } lices upon which they live from the interior. For 

 this class, therefore, some substance must be used 

 which will kill by mere contact with their bodies. 

 Now, for both of these classes of Insects we have 

 cheap and available remedies, of which I will speak 

 further on. 



Remedies for injurious Insects are either Preventive 

 or Active, and must be applied in accordance with 



the circumstances of the case and the habits of the 

 attacking Insects. 



PREVENTIVE REMEDIES. 



These are of two kinds : — 1. Agricultural ; and 

 2. Deterrent. 



1. Agricultural. — These consist chiefly in the adop- 

 tion of such agricultural methods as : — High Culture, 

 which will stimulate a vigorous and healthy growth of 

 the crop and push it on to maturity as soon as pos- 

 sible ; Clean Farming, by which all weeds are kept 

 down and rubbish is prevented from accumulating ; 

 Early or late seeding, so that a crop liable to attack 

 is presented to its enemies, at the time they make 

 their appearance, in such a condition that they cannot 

 injure it ; Rotation of Crops, by which the insects 

 attracted to a locality by a certain crop will not have, 

 in that place, the same crop to feed on the following 

 year. 



2. Deterrent. — Under this head come such opera- 

 tions as painting the trunks of fruit trees with poison- 

 ous, alkaline, or other obnoxious washes to keep out 

 borers, by deterring the female insects from depositing 

 their eggs upon the bark ; the placing of mechanical 

 contrivances on trees to prevent the ascent of insects, 

 as climbing cut-worms, or the wingless female canker- 

 worm moths, which leave the ground in autumn and 

 spring and crawl up the trunks of trees to lay their 

 eggs. 



Destroying or masking the natural odour of some 

 vegetables by scattering amongst them substances 

 possessed of a stronger or disagreeable odour, as gas 

 lime, or carbolic acid. 



ACTIVE REMEDIES. 



Under this head comes the practising of such 

 methods as may be called generally " hand-picking," 

 or the seeking out of insects in their different stages 

 and destroying them. These methods can be best 

 explained under the several insects for which they are 

 useful. The most important active remedies, however, 

 comprise the application of the various insecticides or 

 poisonous substances which are now so largely used 

 for destroying insects, and which are treated of sepa- 

 rately further on. Before passing on to a considera- 

 tion of these it may be well to devote a few lines to 

 the different methods and apparatus for applying 

 insecticides. 



APPARATUS. 



Nearly all of the insecticides may be used both as 

 a dry powder and as a wet mixture. In the case of 

 the arsenical poisons it is necessary to mix them with 

 some other substance as a diluent, on account of their 

 caustic action upon tender vegetation, also for con- 

 venience of distribution, and to economise the material 

 in use. For dry applications suitable diluents will be 

 found in flour, land-plaster, air-slaked lime, and finely 

 sifted ashes or road-dust. It is of the utmost impor- 

 tance that these should be perfectly dry and in a very 

 fine state of division, so as to mix thoroughly with the 

 insecticide used and to allow of being distributed 

 evenly over the plants as a very fine powder. The 

 proper quantity of the diluents to be used with the 



