INSECT LIFE IN INDIA AND HOW TO STUDY IT. 



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issues during other months from wood which has been transported to 

 other elevations, the time passed in the larval and pupal stages being 

 considerably lessened in hotter temperatures. 



This sirex is capable of doing the most serious injury to timber, as 

 the winding galleries of the larva and the exit holes of the mature 

 Insect riddle the wood and make it useless for anything save fire- 

 wood. Fig. 38 shows a piece of wood from a large spruce tree 

 containing numerous galleries made by the larvse. Further study of 

 the habits of this Insect may show that it attacks other coniferous trees. 



Two other as yet und escribed species of this genus have also been 

 recently found boring into spruce in a manner very similar to that 

 pertainable to the sirex. 



Fam. III. Tenthredinidse— Saw-Flies. 



This is an important family, but little is known about its members in 

 India and practically nothing about their habits. The 

 perfect insects have at times a superficial resemblance to 

 a large blue bottle fly, but can be distinguished by 

 having the four wings instead of two ; there are no 

 spurs on the front tibise of the legs. The larvse are 

 very like caterpillars (cf. fig. 39), having three pairs 

 of thoracic legs and six to eight pairs of abdominal 

 ones ; in this they differ from lepidopterous caterpillars, 

 which never have more than five pairs of abdominal 

 legs. Saw-fly larvse feed exposed on the leaves of 

 plants in the same way as caterpillars, or they may live 

 in galls, etc. The eggs are laid in the bark of the 

 twigs of the food plant and may result in large wounds 

 on these latter. 



I have said that the life-histories of these Insects have 

 been very little studied in India, but one or two crop- 

 Fig. 39.— Saw-fly feeding forms being known. Within the last two years, 

 larva feeding however, three species, as yet undetermined, have 

 UP °dl rN w ^ een f° uu d feeding upon coniferous trees in the North- 

 Himalayas.) West Himalayan forests. Of these one infests the 

 deodar, a second the spruce, and the third the silver fir. Observations 

 made on their habits show that they all feed upon the spring crop of 



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