20 FOREST PROTECTION 



Par. 5. Protection Against Insects. 



A. General Remarks. 



I. Insects are the most serious animal enemies of the forest. More 

 than that, they are the worst enemies of the forest within 

 organic nature. 



But in a certain sense, many insects seemingly injurious, are 

 in fact beneficial, since they form one of the means by which 

 nature selects the fittest individuals for the propagation of 

 our trees. 



II. Almost all of the orders of insects contain families, some or 

 all the members of which are directly beneficial. These bene- 

 ficial forms are usually zoophagous, and may be — 



a. Predaceous insects feeding on eggs, larvae, pupse, or 

 imagines of injurious species, notably — 



Order Coleoptera: Families Coccinellidce, Cicin- 



delidce, Carabidce, Elateridce, Cleridce, Trogositidce, 



Colydiidce. 



Order Diptera: Families Asilidce, Syrphidce. 



Order Hymenoptera: Superfamily Formicoidea. 



Order Hemiptera: Family Reduviidce. 



Order Orthoptera: Family Mantidce. 



Many Neuropteroid insects.* 



b. Parasitic insects, ovipositing on or in the bodies of 

 injurious species. The more important are — 



Order Diptera: Family Tachinidce. 



Order Hymenoptera: Superfamilies Ichneumon- 



oidea, Proctotrypoidea, Chalcidoidea. 



e. Parasitic insects, paralyzing their prey by stinging, and 

 carrying them into their nests where the eggs of the 

 parasite are deposited. 



Order Hymenoptera: Superfamilies Sphegoidea, 

 Vespoidea. 



Many families are neither injurious nor beneficial, and are there- 

 fore of no economic importance. Other groups which may be 

 either injurious or beneficial to man, are not mentioned here, 

 because they bear no direct relation to forest trees. Amongst 

 the phytophagous insects, there are however, very many forms 

 that are injurious to our forests. Those living on tree weeds 

 mufit, of course, be considered as beneficial; but speaking gen- 



*The old order Neuroptera, has been divided into several orders in modern systems of 

 classification. The group as a whole is of little economic importance to the forester, and 

 for that reason, the inclusive term, Neuropteroid, is used. 



