A FoREKiN Invasion of England 311 



same cycle in future. More than niue-tenths of 

 the Hessian Hy ^ruhs hatched (uit in America 

 are thus destroyed hy parasites hefore tliey reach 

 maturity ; and it seems hkely tliat the surest 

 way of lij^htinj^ in- 

 sect plaj^ues hke the 

 Hessian fly is by 

 encouraj^inj4 tlie in- 

 crease of sucli natu- 

 ral destroyers. 



At first si^^ht, to 

 be sure, it may seem 

 improbable that man 

 could do anything 

 to ** encourage " the 

 reproduction of such 

 very small creatures ; 

 but that is not really 

 so. All that is ne- 

 cessary is to keep 

 the straw in which 

 the parasitic grubs 

 abound, and so allow 

 the two hostile kinds 

 to tight it out among 

 themselves for the 

 farmer's benefit. 

 Mr. Enock mentions 



an instructive case of this sort from America, 

 where the Californian orange -growers were 

 almost being ruined by the depredations of 

 the scale-insect, a queer little beast which you 



■.o. 15. 



-Wn.Y FAF.MY r.WINr, IIKR KC.C.S 

 IN IIIK lAKVA. 



