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GARDENERS' CHRONICLE 



(OF AMERICA) 

 Devoted to the Science of Floriculture and Horticulture 



I Vol. XXIV JULY. 1920 



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No. 7 



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Things and Thoughts of the Garden 



MONTAGUE FREE 



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E are now in the midst of the open season for 

 insects, and most of us are busy trying to keep 

 them under control. In spite of extensive writ- 

 ings on the subject there are apparently still a few gar- 

 deners who have not yet grasped the fact that there is 

 a fundamental difference in the methods adopted to con- 

 trol insect pests which obtain their food by sucking plant 

 juices and those which actually chew their food. Thus 

 we find a prominent grower advocating in his catalog 

 the use of arsenate of lead ''to keep away aphis or green 

 fly." This is, of course, preposterous as arsenate of lead 

 is a stomach poison, and aphids obtain their food in such 

 a way, by inserting their beaks in the plant tissue and 

 sucking the juices, that they do not absorb any of the 

 poison. Broadly speaking, sucking insects, such as 

 scales, mealy bugs, and aphids, are best controlled, ex- 

 cept when fumigation can be resorted to, by the use of 

 a contact spray or dust which acts by corrosion or by 

 clogging the breathing pores of the insect. Examples 

 of sprays and dusting materials of this kind are nicotine 

 solution, kerosene emulsion, and tobacco dust. On the 

 other hand, those insects which actually eat the leaves of 

 the plants are best dealt with by poisoning their food. 

 This can be done by spraying with one of the arsenical 

 poisons, such as Paris green or arsenate of lead. 



The problem of controlling garden pests is not always 

 so simple as some might infer from the preceding para- 

 graph. For instance there are insects which feed in such 

 a way that they cannot be reached by insecticidal sprays. 

 One of these is the beet-leaf maggot which tunnels be- 

 tween the upper and lower epidermis of the leaf. Here 

 the only remedy indicated is to cut off and burn infected 

 leaves. If this is attended to when the cro]) is harvested 

 it will lessen the danger of trouble the following year. 

 \Mien these pests attack crops which are grown for their 

 leaves, such as spinach and Swiss chard, their depreda- 

 tions are even more serious, for, although it seems im- 

 possible to detect any difference in the flavor of leaves 

 so attacked, the womenfolk, even if they are not vege- 

 tarians, arc somewhat squeamish about finding these 

 maggots cooked in sjiinacb and so when a crop becomes 

 badly infested it is practically valueless. I was fortu- 

 nate enough a year or two ago when searching for the fly 

 responsible for the beet-leaf maggot to find an insect on 

 Swiss chard which was determined by Dr. Chittenden 

 of the U. S. Bureau of Entomology as a parasite on the 

 pest. Unfortunately I have no reliable data to show 

 whether this parasite is sufficiently active in keeping 

 down the maggot to make it of horticultural importance, 



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but the impression is that the maggots were not nearly 

 so prevalent the following year. 



^lany of us, no doubt, inspired by the reports of the 

 success with which the fluted scale was put out of busi- 

 ness in California by a species of lady-bug imported from 

 Australia, have had visions of what might be accom- 

 plished by finding suitable parasites for all of the pests 

 to which our gardens are subject, but we still have to 

 hustle around with the .spray-pump and dust-gun. and 

 will probably continue to do so for sometime to come. 



One often wonders if in some of our spraying opera- 

 tions we do not do considerable harm as well as good. 

 The beneficial larvas of the lady-bug must surely suffer 

 when we .spray with nicotine to combat aphis and we are 

 thus in the position of injuring one of our best friends. 

 But, alas ! it so often happens that we cannot aft'ord to 

 wait until the industrious lady-bug has cleaned up the 

 ajjliis colony and so we proceed on the principle that "if 

 yt)u want a job done properly you must do it yourself" 

 and consequently the lady-bug, is an innocent victim. 



While on the subject of pests the English sparrow is 

 at once brought to mind. It is admitted that he has 

 already been pretty well castigated for his varied mis- 

 deeds by garden writers in many lands, but I have not 

 yet seen any mention of his fondness for taking a dust 

 bath in the midst of germinating seedlings. Of course 

 those areas which contain very small and very choice 

 plants are always selected as the scene of his abandoned 

 wallowings, with usually disastrous results so far as the 

 seedings are concerned. .\ writer in the Garden Maga- 

 cinc calls attention to the fact "recently demonstrated 

 at a British experimental station"' that sparrows have a 

 horror of blue paper. Most of us suffer from the ex- 

 liberance of sjiarrows in the garden at some time or an- 

 other and any means of repelling them is worth trying 

 oul. If strips of blue paper disposed advantageously will 

 prevent them from wreaking their will on the young peas 

 and lettuces gardeners everywhere will be properly grate- 

 ful for the information. It may be, however, that the 

 English sparrow from long residence in America has 

 become so sophisticated as to refuse to be intimidated 

 by blue paper whether it be of ultramarine or forget-me- 

 not ! One of the most effective ways of conveying to 

 the sparrow intelligence the fact that their room is pre- 

 ferred to their comjiany is to trap a few of them with 

 the common "break-back" mousetraps baited with bread. 

 This is a perfectly humane method of despatching them 

 as the traps kill instantaneously. It is not suggested that 



