NUMBER. 1 59 



are of no importance to the forester ; such are the stag-beetle 

 {Lucanus cervus, L.), and many species of Anohiidae and 

 Ceramhycidae. 



Many insects confine their attacks to fully-grown or old 

 trees ; others attack only young plants (Ili/lohius ahietis, L.) ; 

 others attack trees of all ages {Myelopldlus inniperda, L.). 



The attack may be on the roots {GrylloUdpa ruh/aris, L,, 

 Melolontha vidgaris, Fabr., in the larval state) ; on the bark 

 (most species of Tomicus and Hylesimis) ; on the wood 

 itself {Trypodendron lincatum, Gyll., species of Sir ex and 

 Ceramhyx) ; on the leaves or needles (Chrysomela and 

 most lepidopterous larvae) ; on buds (Curcidionidae, Tortri.r 

 huoliana, Schiff.) ; on the blossom {Anthonomus pomorum,'L.) ; on 

 fruits (Balaninus nncum,Ij., Ccuyocapsa jwmonella, L., Tortrix 

 strohillcla, L.) ; on the pith {Myelop)hilus pinipcrda, L.). 



Many insects by biting and sucking produce malformations 

 termed (falis on leaves, shoots, fruits, etc. XCy)dps, Aphis, 

 Cecidomyia, Chermes and Coccidae, etc.) ; such damage is easily 

 discernible, but is of subordinate importance. 



Damage by insects reduces the production of good seed by 

 the trees attacked. Dr. A. Hosaeus investigated the seed of 

 Scots pine from trees attacked by and free from leaf-larvae, 

 obtaining 1 and 45 per cent, of good seed respectively. 



Section IV. — Number. 



The number of individuals of a particular insect that may 

 coexist is in many species limited, but in others may attain 

 vast proportions, especially under favourable circumstances. 

 Thus in 18B4,* 200 square miles of sal forest {Shurca rohusta) 

 in Assam, north of the Bramaputra river, were ravaged by 

 the caterpillars of Dasychira Thicaitcsi, the trees exhibiting 

 complete or partial defoliation. The appearance of certain 

 insects shows a periodicity, corresponding to the eleven years' 

 weather periods. 



Fortunately, the most prolific of insects, plant-lice, are not 

 the most destructive to forests ; these creatures, according to 

 E^aumur, may produce 5,000 millions from one female in the 



* •' Indian Forester," vol. xx., p. 2o(;. 



