AMERICAN BLIGHT. 39 



stout rostrum, or beak, protruding beyond the tail. This 

 organ soon ceases to grow, whilst the rest of the insect 

 rapidly develops. The insects, when adult, exude from 

 their pores long silky threads, which curve round a 

 centre, and often form long spiral filaments, under which 

 they hide. 



The Queen Aphis, or foundress of the colony (see Plate!., 

 Fig. 4), must produce an enormous number of insects; 

 but, when it is considered that the celebrated naturalist 

 Reaumur states that an insect in five generations may be 

 the progenitor of 5,904,900,000 descendants, and it is 

 supposed that in the course of twelve months there 

 may be no less than ten generations, thus exceeding in 

 fecundity that of any other known animal, the difficulty 

 of destroying and of keeping an orchard clean of 

 such an insect becomes a very serious matter, at any 

 rate to those whose trees are not worked on blight- 

 resisting stocks. 



The most common form, Mr. Crawford tells us, is that 

 of the wingless female (see Plate I., Fig. 6), and this, as 

 also the other figures, will be easily understood by re- 

 ferring to " Explanation of Plates." 



Prevention and Remedies. 



When the roots of the trees are badly affected, the soil 

 should be removed from the surface, and either sprayed 

 with a strong kerosene emulsion, or, what would be perhaps 

 better, the application of kerosene in some form of heated 

 vapour, as this, I have lately observed, is of a far more 

 penetrating nature, and seems to be quite harmless to the 

 trees. The application of gas-lime to the roots and soil 

 has also been highly spoken of, and Mr. Tryon, in his 

 excellent book on the insect and fungous pests of Queens- 

 land, gives the following directions for its use, as taken 

 from the Gardeners' Chronicle for 19th June, 1886 :< 

 Spread about one shovelful or more, according to the 

 size of the tree, in a dry state within a radius of 5 feet 



