Jdnb 16, 1921 



The Florists^ Review 



17 



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BATTLING ROSE BEETLE 



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HE strawberry beetle, Ty- 

 pophorus canellus, is rath- 

 er an ambitious insect. 

 It is always striving to 

 get into the limelight. It 

 first succeeded in getting 

 its name into print by 

 destroying strawberry 

 plants; next it caused a 

 stir by attacking apple 

 orchards in New England; but it did 

 not arrive in the "Who's Who" until 

 it began to attack roses under glass. 

 As mentioned, the Typophorus canel- 

 lus was first known as the strawberry 

 root-worm, because of the fact that the 

 larva of this insect works under ground, 

 destroying the roots of the strawber- 

 ries. To the rose growers, the adult, 

 the beetle itself, is of greatest concern, 

 since it is the beetle that does the great- 

 est, at any rate, the visible damage 

 to the rose plants. It feeds on the 

 leaves and on the tender bark of the 

 young growth, also on the eyes as they 

 begin to swell. How much 

 damage is done by the larvae 

 feeding upon the roots is 

 difficult to determine. At 

 times it must be great, for 

 Mr. Dietz, our entomologist, 

 has told me of a case where 

 the tender white roots have 

 been almost entirely de- 

 stroyed. 



A paper read by Herman Jiinge, of Indianap- 

 olis, before the meeting of the Indiana State 

 Florists' Association June 7 at the Smith & 

 Young Co., Indianapolis. 



patent remedies, but no matter what 

 he uses, it seems to be effective. 

 For, beginning about the middle of Au- 

 gust, he notices a decrease in damage 

 done and flatters himself that he has 

 found a remedy to cope with this evil. 

 Encouraged by his apparent success, 

 more diligently than before he attends 

 to spraying or dusting the plants. As 

 the season becomes cooler and the days 

 become shorter the damage and the 

 number of beetles continue to decrease, 

 until sometime in November the rose 

 houses appear about normal. Then the 

 grower, after reconciling himself to a 

 loss of one-half or one-third of his rose 

 crop, discontinues his efforts at the very 

 time when winter weather puts his 

 enemy at the greatest disadvantage. 

 And so it goes, year after year, and so 

 it will continue until we resolve to fight 



Begin in June. 



THE TRADE'S AID 



D D n 



In June, generally between 

 the first and the fifteenth, 

 the signs of the beetle's de- 

 .structive work increase rap- 

 idly, until in a badly in- 

 fested place there can hardly 

 be found a leaf or a bud or 

 four inches of young growth 

 unmarred. For all this dam- 

 age the beetle itself is little 

 in evidence, because it feeds 

 on the under side of the 

 leaves, keeping well out of 

 sight. It also has the habit 

 of "playing possum;" that 

 is, at the sliglitcst disturb- 

 ance it will drop to the 

 ground and lie there motion- 

 less, and being small and of dark color, 

 it is almost invisible. If you wish to 

 get a correct idea of the number of 

 beetles, blow tobacco smoke among the 

 plants. If you listen carefully, you can 

 hear them drop and so get an idea of 

 the number present. Another good way 

 of ascertaining the number is to shake 

 the bushes and immodiatly afterwards 

 let the flame of a gasoline blow-torch 

 play upon the ground between the 

 bushes. The heat of the torch will 

 make the beetles run or fly. 



When the grower sees the increasing 

 signs of another onslaught of the pest, 

 he realizes that his strenuous efforts of 

 the previous season have failed, once 

 more, to rout the enemy. If rose grow- 

 ing is not absolutely vital to his busi- 

 ness, he may decide, as a number have 

 done, to drop rose culture entirely, but 

 if he is not so fortunately situated, he 

 takes up the battle anew. He smokes, 

 sprays, powders or gasses; he uses arse- 

 nate, tobacco, cyanide or some of the 



Combative measures of the Philadelphia 

 rose growers against the strawberry beetle 

 were described in The Review of May 6, 

 1 920. To aid rose growers throughout the 

 country further in their fight against this 

 dangerous pest, the Indiana State Florists' 

 Association voted to submit for publication 

 in the same columns this excellent account 

 of steps taken against the insect in Indiana. 



and watch our enemy, not only when 

 he goes over the top in the balmy days 

 of June, but also while he is lying low 

 during fall and winter, preparing for 

 another campaign. 



Knowledge Needed. 



To win this battle, we must learn all 

 about this beetle; in order to apply our 

 remedies intelligently, we must know 

 all about its habits and its life cycle; 

 we need facts, scientific facts, that only 

 an entomologist is qualified to establish, 

 and here I am glad to report that Harry 

 Dietz, of our state conservation depart- 

 ment, and C. A. Weigol, of the United 

 States Bureau of Entomology, are mak- 

 ing good progress in their efforts in that 

 direction. 



Under natural conditions, according 

 to our state entomologist, the typo- 

 phorus lays eggs in spring; the larvae 

 are feeding upon the roots of the straw- 

 berry during June and July and in fall 

 the mature beetles appear above 



ground, feeding upon the strawberry 

 leaves. The beetles pass the winter in 

 a dormant or semi-dormant state and 

 conclude their life cycle by depositing 

 their cluster of eggs in spring at the 

 base of the plants. 



This is a simple and orderly plan of 

 life and leaves little to surmise. Un- 

 fortunately for us, however, the beetles 

 under glass have adopted a more care- 

 less way of living. No longer do all 

 the beetles deposit their eggs within a 

 week or ten days, but eggs may be 

 found from early spring until late in 

 July, so that at the present time we are 

 uncertain whether there are not two or 

 even more broods reared annually. At 

 the end of last July I found, at one 

 time and within a few inches of each 

 other, eggs, two sizes of larvae, pupa; 

 and beetles in different stages of devel- 

 opment. Indications are, however, that 

 at least from October 15 to February 15 

 the ground is free from these insects in 

 any form, and the beetles above ground 

 arc all that we have to con- 

 tend with during that time. 

 The beetle in winter, say 

 from November until Febru- 

 ary ];"), is sluggish, lying or 

 crawling slowly on the 

 ground. It seldom and only 

 during the warmest hours of 

 the day appears on the 

 plants, and it never flies. 

 That means, and this is im- 

 portant, that at this time of 

 the year it is not likely to go 

 from one bench to another, 

 so that if one bench is 

 cleaned of beetles there is no 

 immediate danger of its be- 

 ing again infested. 



Remedies Tried. 



As to the remedies, arse- 

 nates are most frequently 

 used. We have tried both 

 arsenate of lead and Paris 

 green, and according to our 

 experiments with beetles con- 

 fined in catches, dusting with 

 a mixture of eight parts of 

 flour to one of poison, P.aris 

 green is tiie more effective 

 of the two; it also has the advantage of 

 being less conspicuous upon the foliage. 

 At best, however, arsenates and all 

 other stomach poisons, whether applied 

 as dust or liquid, will reach only a small 

 number of beetles, because this insect 

 habitually feeds on the under side of 

 the leaves and on such other parts of 

 the plant as are the hardest to reach 

 with the poison. Hydrocyanic acid gas, 

 using two ounces per thousand cubic 

 feet of space, will kill practically all 

 beetles caught above ground, according 

 to Mr. Weigel. Since, however, the gas 

 also injures the plants more or less, its 

 use is practical only during a brief 

 period in summer and at that time, as 

 we have shown, new beetles are con- 

 tinually emerging from the ground. 

 Mr. Weigel also reports good results 

 from applications of wood ashes and 

 tobacco dust in controlling the larva;. 

 He writes: "These materials are ap- 

 plied at intervals of five days and at a 

 rate of thirty-five to forty pounds per 



