V f; / 



2 E. A. OEMEEOD — PKEVENTION OF INSECT-INJXJET. 



In considering the question of insect-attacks on our food-crops, 

 and to a certain extent on our fruit, it is of some importance to 

 remember that we are very often, if not for the most part, dealing 

 with plants that are in some way or other in an abnormal state — 

 in an unnatural condition as regards their own vegetable develop- 

 ment ; or the numbers in which they are grown together ; or the 

 soil they grow in. The object of cultivation is frequently to 

 produce an increased development of some particular part, as for 

 instance the enlarged succulent mass which forms the so-called 

 bulb of the turnip, and the mass of close-pressed leafage of the 

 " hearted " cabbage. A greater amount of fruit- cultivation also 

 produces the aggregation of one kind of plant unnaturally over 

 many acres, sometimes (as may be seen especially in the cultiva- 

 tion of cabbage in what is known as " garden- farming ") without 

 due rotation of crops. 



With an increase of population it is necessary to increase our 

 vegetable supplies, but the great increase of the insect-pests from 

 the unavoidable massing together of food-plants which in their 

 natural state would be thinly scattered amongst other kinds, either 

 not infested by the same insects or deterrent to them, is one special 

 point. Where there are only a few plants together of a kind, 

 whether they are killed or not by the insect-attack, the attack 

 itself either dies out for want of food, or is not propagated to any 

 great extent, but where a space of many acres is covered by one 

 crop, if any insect-pest that produces many generations in one 

 season once gets hold, it has everything at hand for continuance. 



Before entering on these points a little in detail, it may be of 

 interest to quote the account given in Holinshed's ' Chronicles,' of 

 the variation in the amount of vegetables cultivated in this country 

 which was observable in a general view of a period of about three 

 hundred years before the date of 1586. The extract is given from 

 the Chapter entitled " Of Gardens and Orchards " in the 1st volume 

 of the ' Chronicles.' 



"Such herbs, fruits, and roots also as grow yearly out of the 

 ground, of seed, have been very plentiful in this land, in the time of 

 the first Edward and after his days : but in process of time they 

 grew also to be neglected, so that from Henry the Pourth till the 

 latter end of Henry the Seventh, and beginning of Henry the 

 Eighth, there was little or no use of them in England, but they 

 remained either unknown, or supposed as food more meet for hogs 

 and savage beasts to feed upon than mankind. Whereas in ray 

 time their use is not only resumed among the poor commons, I 

 mean of melons, pompions, gourds, cucumbers, skirrets, parsneps, 

 carrots, cabbages, navews, turnips, and all kind of salad-herbs, but 

 also fed on as dainty dishes," etc. 



In our own days the quantity of food-crops is enormously in- 

 creased; and as a matter of course there is an increase of the 

 insect-feeders on these crops, but the amount of this increase 

 depends on many circumstances or coincidences. Kegarding some 

 of these we have gained solid practical knowledge — long-continued 



