NATURAL ENEMIES 399 



Birds are believed to be the best insect destroyers in nature. 

 They feed upon insects in all stages. During the nesting period, 

 birds which are ordinarily classed as seed eaters gather large num- 

 bers of insects to feed to their young daily. It has been carefully 

 estimated that a robin will use 300 larvse in a day while feeding 

 her young. The nuthatch, chickadee, hairy woodpecker, brown 

 creeper and similar birds find the hiding places of insects through- 

 out the winter season, thus destroying the few remaining insects 

 of many species in any locality where such birds are not molested. 



The ruthless destruction of birds by man, in search for millin- 

 ery feathers and plumes or for game or for mere sport, has doubt- 

 less done more than any other one thing to destroy the "balance 

 in nature," and allow injurious insects to obtain supremacy. The 

 farmers are willing to suffer losses amounting to hundreds of 

 millions of dollars for the sake of giving a few others the privi- 

 lege of destroying birds. Many states have laws favoring the pro- 

 tection of birds at certain seasons of the year, or throughout the 

 year. Enforcement of such laws results in great good to crops. 

 All possible means for the protection of birds and encouragement of 

 their work should be used. Suitable nesting places for birds may be 

 provided. Bird houses may be erected where cats cannot reach them. 



Toads are wonderful insect destroyers. Some one has said 

 that a toad in a garden is worth twenty dollars a season. Surely 

 their value should not be underestimated and when found they 

 should never be molested. 



There are many insects which prey upon injurious species. 

 These are called predaceous insects. Examples of these are several 

 species of lady bird beetle, certain forms of solitary wasps, wheel- 

 bugs, crane-flies, robber-flies, ground-beetles, tiger-beetles and 

 others. Still other forms are parasitic upon injurious insects. The 

 minute chalcis-flies lay their eggs in scale insects, many injurious 

 caterpillars, such as the cabbage worm and others. When the eggs 

 of chalcis-flies hatch, their larvse feed upon the tissues of their vic- 

 tims and many injurious forms are thus destroyed. It is not an 

 uncommon thing to make a large collection of injurious insects 

 and find them all parasitised by the chalcis-fly. Other common 

 parasitic insects are ichneumon-flies, braconids and others. 



Fungous diseases doubtless play an important part in keeping 

 many species of insects within bounds. The ravages of locusts, 

 chinch-bugs and others are greatly reduced by fungous diseases. 



Efforts have been made by man from time to time to introduce 



