THE PROBLEM OF DEFENCE 171 



specialised protective devices, whether of form, colour, or 

 habit, tend to detract from mere bodily fitness, except in 

 those cases where the creature's manner of feeding demands 

 alert and dexterous movement. Similarly, the sense- 

 organs and instincts are accurately adjusted to the re- 

 quirements of each insect in its own sphere of existence. 

 Doubtless there are some supremely successful species, 

 such as the hive-bee and the ant. whose all-round capacity 

 far surpasses the average. But these exceptions are rela- 

 latively few. Xor is this surprising when we remember 

 how fierce and relentless is the struggle for existence. 

 Moreover, absolute perfection is not desirable, for it would 

 involve annihilation. If an insect were to attain complete 

 immunity from all its enemies, it would, in the course of 

 a few generations, exhaust all possible sources of food, 

 and perish by starvation. 



So far we have considered the problem of defence 

 from the standpoint of the individual insect. But this is 

 only one phase of the question, for Nature's chief concern 

 is to save the species from destruction. So that we may 

 regard all the wonderful contrivances that enable insects 

 to frustrate the attacks of their enemies as part and parcel 

 of one great scheme for the preservation of the race. 

 Pondering the matter in this light, we realise the far- 

 reaching importance of other factors, such as the insect's 

 tenacity of life, its immense powers of increase, and the 

 surpassing vitality of its eggs. The latter may be sub- 

 jected to a far greater range of temperature than the 

 animal could survive in any of its three other stages. In 

 what manner this stubborn resistance is contrived we do 

 not know. But it is a fact that eggs laid in the autumn, 

 and not hatched until the following spring, pass unscathed 

 through the severest frosts. Again, the reproductive 

 capacity of many insects is amazing. One instance will 



