Insect Pests and Fungoid Diseases. 



407 



Cabbage Aphis. 



1 and 2. male ; 3 and 4, wingless female ; 

 natural size and magnified. 



tubes near the end, through which it is supposed that they pass excretions. 

 Aphides injure plants both by sucking out the sap and so weakening their 

 vitality, and also by interfering with the functions of the leaves by blocking 

 up the stomata or pores with their excretions, known as "honey-dew," 

 a sticky substance much relished by ants, which often ascend the plants to 

 obtain it. Some aphides cause the leaves to curl, so enclosing them and 

 making it difficult to reach them with washes. 



Aphides are almost incon- 

 cievably prolific. They not 

 only produce eggs which 

 hatch out in due course, but 

 produce young alive. They 

 not only breed in the ordin- 

 ary way but the fecundation 

 of one female is sufficient to 

 render twenty succeeding 

 generations fertile, each of 

 the young aphis being able 

 in a very short time to pro- 

 duce further living young. 

 There is scarcely a culti- 

 vated crop which does not suffer more or less from aphide attacks, almost 

 every variety of plant having its own particular aphis, of which the Cabbage 

 Aphis illustrated may be taken as a fair sample of the type. When their 

 extraordinary powers of reproduction are considered it will be seen that if 

 allowed to multiply unchecked they would soon over-run and cripple a crop. 

 Dry hot weather which is unfavourable to the growth of plants is very 

 favourable to the increase of aphides, and if they are allowed to get a firm 

 hold of a crop under such circumstances they may totally destroy it. 



Treatment : Spray the plants with paraffin emulsion or nicotine ; or 

 soft soap may be used (6 to lOlbs. of soft soap to 100 gallons of soft water) 

 where the attack is not severe. In all cases it is important to deal with 

 their attacks in the early stages, before the plants have become badly in- 

 fested, and this is particularly the case with leaf-curling aphides. 



CHAFER BEETLES, or White Grubs. Chafer beetles may be recog- 

 nised by their antennae or "feelers," which are club-shaped, with several 

 flattened "leaves" or divisions at the ends. The grubs are thick, fleshy, 

 and of a whitish colour, with the tail curved downwards and swollen, and 

 darker in colour than the rest of the body ; the head is large and brown, the 

 mouth being armed with strong mandibles. They belong to several genera, 

 of which the Cockchafer, the Summer-chafer, the Garden-chafer, and the 

 Green Rose-chafer are occasionally more or less troublesome to gardeners. 

 In habits and general appearance the grubs are similar, but when full-grown 

 there is a marked difference in size, those of the cockchafer and green rose- 

 chafer being much the largest, attaining a total length of one-and-a-half 

 inches. They are all voracious feeders, the damage they do in- the larval 



