228 APPENDIX. [No. XV.B. 



spoken of by Orosius, St. Augustine, Barrow, and others; but the first 

 account of such plagues is handed down to us in the 8th and 10th chapters 

 of Exodus. Another example is furnished by the cockchafer of this 

 country, which increased so excessively some years ago as to destroy every 

 plant and blade of grass existing in various districts. Other insects have 

 also at various times been most destructive ; but I may refer you to the 

 delightful work of Kirby and Spence on Entomology for most interesting 

 information on these subjects. My observations and researches touching 

 last year's scarcity have proved to me that its cause was attributable to a 

 preternatural increase of an insect of the family of the aphides, a tribe so 

 small that they may be passed unseen and unnoticed, though assembled in 

 vast nations on the plants around, subsisting on and destroying an 

 important item of the food of man. This insect, so insignificant in 

 appearance, has thus given rise to considerations of high importance : it 

 has produced famine in Ireland and Scotland, scarcity of the means of 

 subsistence in England, and the effects of its ravages have disturbed the 

 political relations of the whole habitable globe. My previous observations 

 and the facts I had collected on this subject are before the public, which 

 amount to testimony the accuracy of which cannot be disputed. I am not 

 here to-night to enunciate any new thing, but simply to draw your careful 

 attention to such facts as the present season affords, in order that you 

 may consider what may be the best means of averting future ravages, with 

 their consequent scarcity and distress. Aphides, as I have stated, are very 

 small creatures, but frightfully prolific. On a moderate calculation, one 

 aphis may be the progenitor of ten, and each future one of ten more ; so 

 that, increasing in geometrical ratio, the first aphis may become the 

 ancestor of a quintillion at the end of the season ; arriving at an amount 

 so vast that it almost overcomes the understanding. Ten generations of 

 aphides increasing in this ratio, each one producing ten, if placed the 

 head of each at the tail of another, would form a circle extending round 

 our globe : indeed, their fecundity is most enormous. Aphides will exist 

 in all parts and through all seasons. They are very tenacious of life, and 

 are connected with all scarcities, not only the present, but no doubt with 

 many that are past. 



In investigating the nature and character of these insects, it be- 

 comes necessary to ascertain the quality of their food, which must consist 

 of organic matter, animal or vegetable, and also must be either dead 

 or living animal or vegetable matter. As an illustration of such inquiry, 

 the leaves of the strawberry-plant before me were found covered with 

 black spots similar to those observed on the leaves of the diseased 

 potato, &c. I had this strawberry-plant placed in a pinery where no 

 aphides existed, but in due time these black spots on its leaves were 

 further developed, and became insects, each of which passed through the 

 various stages of its insect life, from the larva to the pupa, and from the 

 pupa became the imago or perfect winged aphis. In these conditions 

 it was found living and feeding on the leaves of the plant; therefore 

 its proper food is demonstrated to be vegetable, and living vegetable, 

 matter. 



The next inquiry, and one which has been controverted, is whether the 

 vegetable matter on which the aphis subsists be healthy or diseased. This 

 strawberry-plant, when first placed in the pinery, was healthy-looking and 



