Gardening for Amateurs 



677 



Insect Enemies and Friends and Plant Diseases 



MODERN horticulture has become 

 highly intensive. In the evolu- 

 tion of the science we have 

 specialised to a great degree, and in 

 doing so there has been lost that sturdy 

 hardihood which is the attribute of the wild. 

 More and more weak have the individuals 

 become, and this weakness shows itself in 

 the greater liability to attack from pests of 

 various kinds. The gardener and horticul- 

 turist have upset the natural balance of 

 vegetation ; they wish to grow hundreds of 

 one variety of plant in a spot which Nature 

 intended to be clothed with a great many 

 different plants, all in active competition, 

 hardy and strong in their struggle for exist- 

 ence. It is to be expected, then, that pests 

 have increased with this specialisation ; while 

 the deprivation of plants of their free charac- 

 teristics, and selection of abnormalities, has 

 removed their immunity from disease, that 

 hardy wildness of the gardens of a past 

 generation. 



An old gardener, commenting on the 

 present state of affairs, bewailed the fact 

 that every plant has its pest, and some many 

 more than one, nowadays ; in the main 

 we have to admit the fact, and knowing the 

 likelihood of attack from some of these 

 pests, we must prepare ourselves before- 

 hand. The present system of gardening 

 has evolved these evils, ever increasing in 

 number, ever becoming more virulent, and 

 to cope with them successfully we must 

 understand their life history and their habits 

 and try to find out the best preventive 

 measures we can adopt against them ; total 

 eradication seems an impossible ideal. 



Life Story of an Insect. Let us take 

 the life history of our insect pests. The 

 insect, during her life of pleasure, finds time 

 to deposit eggs here and there about the 

 garden, carefully hiding them from likely 

 enemies and near a supply of food for her 

 hungry offspring. Sometimes these eggs are 

 laid in the ground, sometimes in convenient 

 crevices of the walls or trees ; perhaps she 

 punctures the skin of a leaf and deposits 

 them there, or she may simply place them 



anywhere and cover them up as well as she 

 can to protect them. The number produced 

 varies ; some insects lay a few eggs only, 

 others a dozen or two, while quite a large 

 number leave hundreds about the garden. 

 They are, of course, very small, yet often 

 quite visible, and as each one may develop 

 into a pest the need for action, and early 

 action, becomes only too obvious. The eggs 

 hatch out at some time of the year and 

 produce a grub, maggot, caterpillar, or 

 larva which is generally very much unlike 

 the mature insect. As soon as the larva is 

 born it looks round for something to eat. 

 Practically without exception these larvae 

 have a voracious appetite, and the huge 

 amount of foliage and other material they 

 can consume and destroy is well known to 

 everyone. By and by the surfeited grub 

 becomes sluggish in movements, and finally 

 it hides somewhere to get the better of its 

 long feast ; the outer skin hardens to form 

 a case or it spins a cocoon round its body, 

 and the larva, now grown into a pupa or 

 chrysalis, rests in a most quiescent condi- 

 tion for some time in a cosy warm corner 

 of the garden or deep in the soil. After a 

 time in this torpid condition the pupa begins 

 to wriggle, the shell or case bursts open, and 

 forth comes the insect, stretching its wings 

 in the sunshine and ready to set out on a 

 happy round of pleasure. Truly a wonderful 

 cycle of changes before the mature insect 

 is born ! 



Insecticides. Insecticides are necessary 

 in horticulture to prevent insects depositing 

 their eggs on our bushes and plants ; if we 

 can keep them away the grubs or larvae will 

 never trouble us. Destroy any grubs that 

 are noticed by dropping them in salt water 

 or lime, kill the torpid pupae, and squeeze 

 between the fingers any tiny nest of eggs 

 noticed about the ground. 



Fungi. We have other pests besides 

 insects. The fungi, including moulds, rusts 

 and mildews, which attack our plants are 

 of vegetable origin. These fungi cannot 

 fly or move about from bush to bush, but 

 the enormous number of spores or " seeds " 



