THE SCHOOL GARDEN. 307 



Various caterpillars or caterpillar-like creatures will be 

 found upon currant and fruit bushes, trees, etc. As 

 already suggested, if their real nature is unknown, speci- 

 mens should be transferred to the insect boxes in school 

 and the development traced. 



Green Fly or Plant Lice (Aphides'). These insects 

 are extremely common; they occur on fruit, peas, roses, 

 as well as upon various field crops. They belong to the 

 order of Bugs (Hemiptera), and if they are turned 

 over and examined with the help of a lens, the long 

 pointed boring snout which they insert into the plants 

 they infest can be seen. By means of this borer they 

 suck up the juices of the plant, and since they occur 

 in considerable numbers they are capable of a large 

 amount of destruction. They also injure the plant in 

 other ways, e.g. they excrete a sugary fluid (honey dew) 

 which coats the surface of the leaves, making them sticky, 

 clogging the stomata and thus further injuring the 

 plant. 



These insects have a remarkable history. It will be 

 observed that most plant lice are wingless ; only occasion- 

 ally are winged examples to be seen. The winged forms 

 appear chiefly when the host plant is overcrowded, and 

 these fly away to a new plant and there start a fresh series 

 of generations. Throughout the season there are no males, 

 only a succession of generations of females. In the 

 autumn, however, males appear. These mate with females 

 and the eggs subsequently laid remain dormant all winter. 

 In the spring there develop from these a generation of 

 females, which give rise to young, also all females, and 

 this is continued throughout the summer. " There are 

 species in which each female bears from eighty to one 

 hundred young, and nine to sixteen generations succeed 

 one another in the year " (Ritzema Eos). 



The Aphides thrive best and multiply to the greatest 

 extent in dry warm weather. Spraying the bushes as 

 soon as they are noticed with some destructive fluid is the 

 usual method adopted for their removal, e.g. a mixture 

 of paraffin water and soft soap. Even liberal spraying 



