SPOLTA ZEYLANICA. 67 



OH THE PHYTOPHAGOUS AND PARASITIC HYMENOPTERA 

 COLLECTED BY MR. E. ERNEST GREEN IN CEYLON. 



By P. Cameron. 



Plates A and B. 



INTE0DUCTI0IS\ 

 nriHE Ichneumonidae and other Parasitic Hymenoptera are — 

 -*~ as Dr. Sharp remarks in his volume on Insects (Cambridge 

 Nat. Hist. ?°iries) — " One of the most neglected of the great groups 

 of Insects, though perhaps of greater economic importance to 

 mankind than any other." Besides the truly parasitic families, 

 the group is usually made to include the gall-flies — insects which 

 must be considered as inimical to mankind. It is, however, 

 with the former families — those that prey upon the vegetarian 

 insects — that we are chiefly concerned and that form the principal 

 subject-matter of Mr. Cameron's paper. 



The importance of the Parasitic Hymenoptera will be recog- 

 nized when it is understood that there is probably not a single 

 vegetarian insect that does not constitute the host of one or more 

 species of these parasites. Dr. Sharp states (loc. cit.) tliat the 

 destructive " winter moth " (a serious pest of fruit trees) is 

 known to be attacked by sixty-three distinct species of Hymen- 

 opterous parasites. 



This neglect — by the generality of entomologists — must be 

 attributed partly to the difficulties of determination and partly 

 to their somewhat uninteresting exterior, for the family does 

 not rank among its members many beautiful or remarkable forms. 

 But the lack of conspicuous external beauty is amply compen- 

 sated by the interest and complexity of their habits and 

 development. 



In spite of this comparative neglect, nearly 6,000 species of 

 Ichneumonidae have been described. By far the greater number 

 of species undergo their early development inside the bodies 

 of their hosts. The adult female is usually provided with a 

 prominent slender ovipositor, by means of which the eggs are 

 inserted into the tissues of the victim. The resulting larvae 

 subsist upon the juices (the lymph or blood), taking up all the 



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