270 



THE GARDENERS' CHRONICLE. 



[April 27, 1912. 



FRIEND OR FOE P 



The gardener who is engaged in turning over 

 his farmyard manure in various stages of de- 

 composition, or is mixing his leaf-mould, often 

 finds a variety of living creatures in addition to 

 the larger earthworms with which he is already 

 familiar. What are they? May he feel uneasy 

 at the sight, or should he be glad that they are 

 present? How can he tell whether they are 

 beneficial or injurious? Is it possible that they 

 may help him in one stage of development or 

 in one situation, and yet be a real source of 

 danger in another? I imagine that many a 

 thoughtful gardener has, like myself, had such 

 questionings as these, and has wished for some 

 one to guide him. 



Let us first notice a few of the things we are 

 likely to meet with. Of the earthworms, brand- 

 ling, gilt-tail, and other large species, I need not 

 at present speak. But here are a number of 

 smaller things, most of which are more or less 

 worm-like in outline and appearance. Out from 

 the leaf-mould a number of creatures, possessed of 

 a greater or lesser number of legs, emerge. They 

 are at once seen to be centipedes or millipedes. 

 Among them is the familiar Julus, which bears 



Fig. 130. — MILLIPEDES. 



rather a bad name, and is certainly dangerous 

 under certain conditions. Then there are smaller 

 or larger mai ots, and in the ease of the latter 

 there is no difficulty in deciding what they are. 

 They are stoutly-built, their heads may be easily 

 seen, and their movements are such that we can 

 at once recognize them. Not so, however, with 

 the smaller forms. Even with the pocket lens, 

 which every careful gardener arwaya carries, it 

 may be difficult to decide whether we are look- 

 ing at a grub or at one of the many species of 

 worms which they so closely resemble. 



I think, however, it is a safe rule to assume 

 that all the living creatures found in decaying 

 mould and manure are useful, so long as the pro- 

 cesses of decomposition are in progress. The 

 worms break down the waste material and 

 hasten the processes which are going forward to 

 fit the decaying material for further use in the 

 nourishing of living plants. I .should allow the 

 worms and other creatures to do their work in 

 peace. Then the centipedes and grubs are also 

 useful both as scavengers and as police. They 

 help to maintain the balance of nature, and keep 

 in their place certain forms of life which would 

 otherwise become too numerous, and so prove 

 injurious. The evil comes when the manure 

 heap is a breeding ground for flies, insects and 

 other creatures which presently emerge and be- 

 come a pest in the byre, the stable, the home, 

 or the garden. Maggots and larvae as such, 

 while in the refuse, are not usually a source of 

 danger. It is, however, a question of great im- 

 portance, what is to be done to keep the harm- 

 less larvae from becoming a harmful pest? May 

 the friend become a foe? And may the worms 

 and grubs which are beneficial while in the 

 manure heap, become a source of danger when 

 the manure or leaf-mould are wheeled on to the 

 borders, taken into the potting house, or allowed 

 to remain until the life-history of the creature 

 is complete, and swarms of living things wing 

 their way in every direction? 



Manure heaps become a source of danger in 

 •pring. It is then, as a rule, that two things 



happen. (1) As the weather becomes warm 

 armies of flies of a variety of kinds emerge from 

 the mixen, carrying with them all sorts of germs, 

 or making straight for the places where they 

 can lay their eggs and work destruction amon 

 the plants. (2) Or, if the worms are true worms, 

 and not grubs, they are wheeled into the garden 

 with the manure in which they have been breed- 

 ing, and deposited there to find a living as best 

 they c«in under the new conditions in which 

 they find themselves. Doubtless many fall a 

 prey to the beetles, centipedes, birds and other 

 fierce assailants which are alwavs on the look-out 



head from the tail. 



fly 



But as a rule the larva of 

 has a well-defined head. 



may 

 measures 



for something in the soil to feed upon. Others, 

 perhaps, finding no suitable pabulum in the soil 

 which as yet is in a rough condition, perish, and 

 give up their stores of nitrogen to the soil. But 

 if it happens that the manure is placed on a 

 plot of ground which is already planted, or a 

 plot which will be planted immediately, who 

 shall say that the worms will not begin to prey 

 upon the flowers or vegetables and prove a 

 dangerous pest? 



That a number of white worms, as well as wire- 

 worms, leather jackets, centipedes and other 

 creatures now infest growing plants, and work 

 much havoc among Asters, Strawberries, bulbs, 

 Celery and other garden and field crops, is well 

 established. The question, therefore, arises "How 

 can we distinguish the creatures which are likely 

 to be injurious, and what can we do to check 

 their ravages?" Perhaps the chief difficulty 

 lies in the fact that, in the first place, the worms 

 and grubs are very small, and cannot be dis- 

 tinguished by the naked eye; and then that 

 they are so much alike that, even if the expert 

 can distinguish them in the study and laboratory, 

 no such distinction is possible in the field. If 

 anything is done the innocent and the guilty 

 must alike be subjected to the same treatment, 

 and it must be left to the innocent to find a way 

 of escape. It may seem a hard doctrine, but at 

 present we do not see that any other can be 

 preached. 



I have before me now a number of living 

 creatures which I have obtained from manure 

 heaps and decaying matter. In the usual course 

 of things these creatures would be taken on to 

 the garden, and the question is, would they 

 be beneficial or injurious? Is it wise to take 

 such material into the garden without first mix- 

 ing it with some one or other of the preparations 

 which are destructive of germ and insect life? 

 If my bulbs and beds and trenches suffer may 

 the blame be laid to the living things which 

 swarmed in the manure? These are such vital 

 and practical questions that they demand an 

 answer. 



Examining the organisms then with my pocket 

 lens I find that they vary from £ inch to 1 inch 

 in length, and that while the smallest are like 

 a tiny snip of the finest white cotton the largest 

 might be an inch of fine twine galvanized into 

 life. I put aside the larger forms because it is 

 easy to see that they are the grubs, maggots or 

 larvae of different kinds of flies. If allowed to 

 live they will in due time change into blue- 

 bottles or some other form of diptera, and do 

 more or le^s harm both as germ carriers and by 

 depositing their eggs where they are not desired. 

 But it requires a little skill and patience to dis- 

 tinguish the smaller forms k and a few simple 

 rules may now be advanced to aid the student in 

 his determination. 



In the first place we count the number of seg- 

 ments into which the body is divided. If there 

 are 13 we may be pretty sure we are locking at 

 a grub or larva. It is possible that we may 

 be in doubt as to the exact number, for some- 

 times one or other of the segments is marked, 

 but if we find 12 or 13 we shall have our first 

 clue. There are few white worms whose seg- 

 ments number fewer than 20, whereas nearly all 

 larval forms have about 13. 



Next we look for the head. In the case plant. 



„ usually browner 

 than the rest of the body, and provided with 

 sundry organs such as worms never posee* 

 Moreover, the white worms move backward 

 readily as forwards, whereas the grub usually 

 prefers to let the head lead it. 



Our surest guide, however, lies in the struc- 

 ture of the body. If the creature under review 

 possesses a number of tubes and vessels which 

 can be easily seen under the integument, run- 

 ning through the entire length of the body, we 

 are in all probability looking at a grub. ' If 

 on the other hand we see four sets of tinv 

 bristles on each segment, and find that the tubeg 

 and vessels are either wanting, or are limited 

 to a few of the foremost segments we may on- 

 clude it is a worm. We shall find, usually, 

 that the integument or skin of the larva is much 

 less tender than that of the worm, and as the 

 former is usually harmless in the garden we may 

 take comfort from the thought that if we attempt 

 to destroy the injurious worms the insecticide 



not cause the larva to suffer. 



doubtless wiTl involve the 



St re rig 

 innocent 



with the guilty, but the careful use of germicidal 

 will leave the gardener's conscience free. 



We have now learned to distinguish grubi 

 from white worms. But before I pass to our 

 next point it may be well to give the main differ- 

 ences in tabular form for ready reference in 

 the future. 



Characters. 



Number of seg- 

 ments 

 Head 



Bristles or setae ... 

 Tubes and vessels 

 Colour 



Grub. 

 Thirteen 



Well-defined 

 Absent ... 

 Clearly seen 



Variable ... 



White Worm, 



Twenty and u^ 



wards. 

 Not distinct. 

 Present. 

 Few or absent 

 White. 



of worms the two extremities of the body are 

 so nearly alike that it is sometimes necessary to 

 magnify the creature highly to distinguish the 



Since the grubs of which I am writing are not 

 of the kind to work injury in the garden we 

 may now dismiss them from consideration. The 

 white worms, so long as they were confined to 

 the manure heap and the leaf-mould, were bene- 

 ficial. But of late years it has been clearly de- 

 monstrated that certain fpecies are either per- 

 sistently injurious, or become so under certain 

 conditions. I gave, in these pages, some years 

 ago, an account of a small white worm which 

 was doing immense harm up and down the coun- 

 try to Asters and other plants. I have also 

 found Celery trenches infested with other forms, 

 while Clover and a variety of other crops hive 

 from time to time, been known to suffer greatly 

 by their depredations. I always look upen the 

 white worms with suspicion, and hold that every 

 endeavour should be made to keep them out of 

 the garden. The Aster wxxrm is usually very 

 abundant where leaf-mould is forming, and n 

 the gardener has sJjh mould brought to him 

 from copse or woodland he should use it vita 

 the greatest caution. I therefore advise that 

 whenever it is proposed to carry manure on to 

 the garden it should first be well inspected to 

 see whether or not white worms are V reae ™' 

 If they are, the manure should be mixed *** 

 lime or treated with one of the usual prepara- 

 tions for the destruction of pests. , 



In the case of mould which may be infest^ 

 the need for care is even greater. The wor 

 are minute, and may easily escape detec i • 

 The mould may be mixed with ingredients w^ 

 potting purposes which encourage the *° 

 for a time till they find their way to the rootie 

 of the growing plant. In this case I s ™£ 

 recommend that the mould be baked, 

 process kills the worms and their egg C *P S £ 

 while it does not prove injurious to ^.^ 

 Indeed in many cases a new set of con ^ 

 arises which makes the baked soil all tne 

 productive ; and such a process is tar **x ^ 

 the application of germicides to ^..^f t hat 



If these hints are followed I belu* ■ ^ 

 there will be a greatly reduced risk m ^ 

 when manure and leaf-mould are broug 

 use. Hilderic Friend, Swadlincote. 









