CHAPTER II 

 USEFUL INSECTS 



It is well to remember that insects are not all harmful. On the contrary 

 many plants have become dependent on insect agency for the perpetuation 

 of the species, and this useful work is especially carried on by Bees, 

 Butterflies, and Moths. But besides this, there are many insects which 

 are indirectly beneficial by reason of their carnivorous habits, being either 

 predatory or parasitic species living upon injurous forms. Were it not for 

 their presence in the enemy's camp certain insect scourges would often 

 get beyond human control. We will endeavour to point out a few of 

 the more important useful species in the hope that it may induce cultivators 

 to pause before they contract the habit of killing every creature that 

 creeps, crawls, runs or flies. 



The Order Coleoptera furnishes several examples of useful insects. 



The Green Tiger Beetle (Citindela campestris) is a voracious creature 



both in the larval stage and when it becomes a perfect insect. It inhabits 



bare banks and sandy heaths, preying indiscriminately on other insects, 



often mounting upon the wing with the rapidity of a blue-bottle fly. It 



measures i in. or more in length, and is of a fine green colour, glossed 



with coppery red, and having five yellowish-white spots on the margin of 



each elytron, and another towards the middle. It is one of the most 



beautiful of British beetles. The larva lives in a cylindrical hole in the 



sandy soil, lying in ambush at the entrance with jaws expanded ready 



to seize its prey. The excavation is nearly perpendicular at the mouth, 



and the grub anchors itself to the side by means of two strong fleshy 



tubercles rising from a hump on its back near the tail. When about to 



pupate the grub seals the entrance and retires to the bottom of the hole. 



The Bombardier or Artillery Beetle {Brachinus eocplodens) has the head 



xlv 



