3IO 



Flashlic.mts on NATI'KK 



most closely approach its own peculiar j^round- 

 tint. 



It is a curious fact, however, that in spite of a! 

 the apparent pains bestowed upon securin<4 the 

 perpetuation of such destiuctive creatures as tiie 

 Hessian lly, the pest itseU has its own enemies,' 

 as fatal to its life as it is to the barley. Ichneumon 

 Hies an.l other parasites prey by millions on the 

 Hessian Hy in its s^rub condition ; and many j^ood 

 authorities believe that the safest way of checking 

 the depredations of the barley-plague is by en- 

 couraj^int^ the multiplication ol its natural enemies. 

 No. 15 shows us one of these industrious little 

 scourges actually at work. She alights on a stem 

 of barley infested by j^rubs ot the Hessian liy, and 

 walks slowly alon<4 it, tappinif Lj;ently as she j^oes, 

 much as a woodpecker taps with his bill on a 

 tree-trunk to discover the spot where a worm lies 

 burierl. After carefidly examininj^ the surface, she 

 finds at last a place where somethin<4, either in 

 the sound or the feelinj^ of the stem, reveals to 

 her the presence of a Hessian fly Lfrub within the 

 leaf-sheath. Havinj^ accurately diai^nosed the spot 

 (like a doctor with a stethoscope), she brinj^s her 

 ovipositor (in plain F^ni^lish, her ei^i^-layer) just 

 above the place where the .i^rub is lyin<4 snug in 

 its j^reen bed, and pierces the hard leaf-blade with 

 her sharp little lancet. Then she lays her c^^ in 

 the body of the larva. This e<^g skives rise in time 

 to a parasitic grub, inside the hrst one ; and the 

 parasite eats out his host's body, and emerges in 

 due time as a full-grown fly, ready to carry on the 



