jJo. 5. ] A/iseellaneous Notes. - 41 



females with mouth parts developed for blood sucking. The male is 

 likely to be a harmless insect with rudimentary mouth parts. 



The figures are after Becher. The natural size of the insect is indicated 

 by a hair line. 



A point which has been brought forcibly to notice in prosecuting the 



investigation of the Economic Entomology of 



Identification of Dip- j^^^j^ ^ ^^^^ ^^^^ ^^^^^^ ^^ ^|^-^j^ defoliating 



terous parasites, , _ ^ 



caterpillars in this country are kept down by the 



attack of parasitic Diptera. • Again and again caterpillars sent to the 

 Museum as occasioning damage to agricultural and forest plants have been 

 found to harbour these parasites in such numbers as seriously to interfere 

 with the rearing o£ iraagos for idsntification. And there is little doubt 

 that the sudden disappearance o£ destructive caterpillars, which is so 

 •characteristic a feature of this form of attack in India, is very frequently 

 due to this cause. The loss and inconvenience caused by the Bengal silk- 

 worm 6y [Tricholyga bombycis, Becher) to rearers both of the various 

 mulberry feeding varieties and also of the castor oil feeding Eri 

 {Ai/:acus ricini) is well known, but the question of the identity of the 

 parasites of the various defoliating species has not hitherto been satisfac- 

 torily determined. 



The question is obviously one of very considerable importance, in 

 view of the extent to which these parasites act as a natural check upon 

 the multiplication of destructive caterpillars. The possibility, however, 

 of propagating them artificially depends very largely upon the extent to 

 which diflFerent species of Lepidoptera are capable of harbouring the 

 same species of parasite. The number of species of caterpillars which 

 are liable at different times to cause injury as defoliators in this country 

 is enormous. Indeed it is hardly too much to say that almost every 

 plant has its own special enemies amongst the Lepidoptera. It is only 

 occasionally however that any particular species of caterpillar multiplies 

 sufficiently to cause serious injury. If therefore each caterpillar had 

 special parasites to itself the difficulty of keeping up a supply of these 

 beneficent creatures, in years when the caterpillar was scarce, in order 

 that they might be available for distribution when the caterpillar was 

 actively injurious, would be almost insurmountable. If, on the other 

 hand, it should prove that numerous species of caterpillars are subject to 

 the attack of one species of Diptera the difficulty of keeping up the 

 supply would be very much lessened. In particular it was desirable to 

 ascertain the extent to which the species Trieolyga bombycis attacks 

 caterpillars other than the silk producing Bowbyx and Eri^ for an 

 unfailing supply of this parasite is always available in the silk rearing 

 districts of Beng-al, 



