14 A BOOK OF INSECTS 



certain minute parasites (Mallophaga) which live among 

 the feathers of birds. 



The number of eggs laid by the individual insect varies 

 greatly according to the species. Some of the solitary 

 bees and wasps lay only a dozen or so. On the other 

 hand, it is estimated that the queen hive-bee, surrounded 

 as she is by a vast army of willing nurses, may lay as 

 many as a million eggs in the course of her career. The 

 methods of egg-laying are equally diverse. Some insects 

 deposit their eggs singly, others in groups or clusters. 

 Each species adopts a characteristic method ; while the 

 eggs are almost always laid either upon, or close to, the 

 substance upon which the offspring is destined to feed. 

 Sometimes they are actually inserted into the food sub- 

 stances by means of a special organ, called the ovipositor. 

 Occasionally the eggs of insects are enclosed in a kind of 

 pod or capsule. This is the case with the common cock- 

 roach. It lays its eggs in batches of sixteen at a time, 

 each batch being packed in a mahogany -coloured recep- 

 tacle — eight eggs on one side, eight on the other, in two 

 parallel rows. The mantids, or praying insects, adopt a 

 somewhat similar plan; but their egg-packets usually 

 resemble wild fruits or seed-vessels. Moreover, the man- 

 tids always attach them to some object, such as a stone, 

 a twig, or a grass stem ; whereas the female cockroach 

 carries about her egg-capsule until she finds a convenient 

 crevice in which to hide it. 



A statement is sometimes made to the effect that 

 insects never grow. Obviously this can only be accepted 

 with considerable reserve, for if we compare the egg of 

 any insect with the insect itself, we perceive that an 

 astonishing transformation must intervene to bridge over 

 the difference between the two. The fact is that an adult 

 insect, such as a moth or a beetle, does not grow ; but 



