23 



THE CANADIAN HORTICULTURIST 



Floral £}<Ution. 



Full-grown larvae of the Fruit-tree Leaf-roller. 

 (Natural size.) 



has the same habits, but is, as has been 

 said, seldom at all abundant. 



Nature of the Injury. 



The larvae of the Fruit-tree Leaf- 

 roller attack the leaves, fruit-buds, or 

 blossoms, and also the fruit. The at- 

 tack on the leaves begins about the 

 time they begin to open. At this date 

 the little larvae have just hatched out 

 of the egg. They at once work their 

 way in among the unfolding leaflets, 

 fasten them together with a few silken 

 threads and feed upon the inner tissues 

 in this sheltered position, Avhere it is 

 clear one cannot reach them with a 

 spray mixture. As the leaves get larger 

 they roll them either up or down, but 

 usually np, keeping them in this , posi- 

 tion by a little silken web. In these 

 they feed, often eating holes right 

 through them or devouring part of the 

 top or base. The fruit buds are often 

 bored into and destroyed and, when the 

 blossoms have opened, these are often 

 webbed together, and some of them de- 

 stroyed. 



Once fruit begins to form the cater- 

 pillars prefer it to anything else, and, 

 coming out of their hiding places, they 

 eat holes in it. These holes frequently 

 extend to the core, but often do not go 

 so deeply. The Avorst injured apples 

 drop; the rest remain on the tree, but 

 are deformed and seldom are good 

 enough to grade as anything but culls. 

 It is by the attack on the fruit that 

 the chief injury is done. 



Pears often suffer severely; plums 

 are also subject to attack, but so far 

 the chief injury has been to apples. The 

 pest is not confined entirely to fruit 

 trees, as it also feeds and breeds to some 

 extent on forest trees. In the orchard 

 the caterpillars will, where there are 

 weeds or clover, drop down in large 

 numbers and feed on these, but we have 



never found eggs on any of these plants 

 but only on trees. 



Brief Life-History. 



. At this lime of the year (January) 

 the insects are in the egg stage. The 

 eggs are laid in small clusters and 

 nearly always on the upper side of two 

 or three year old twigs. This is the 

 place to hunt for them. The clusters 

 are, as seen in the photo, about one- 

 quarter of an inch or less in length, 

 and are oval and dark brown in color. 

 After hatching they soon become near- 

 ly white, and show the little holes out 

 of which the caterpillars come. Eggs 

 do not begin to hatch until the leaf- 

 buds have started to burst. Hatching, 

 however, continues for nearly a month, 

 especially ii the weather is cool. 



The young larva attacks first the 

 opening leaflets, then the larger leaves, 

 fruit-buds, blossom and fruit. About 

 the middle of June they begin to be 

 full grown, and by July 1st moths may 

 be seen in the orchard. During the day 

 the moths conceal themselves among 

 the foliage, but if the branches are 

 shaken they will rapidly fly out with a 

 zig-zag motion and usually go down 

 into the grass or weeds to hide. Late 

 in the evening they begin to fly ar. aiud, 

 mate and lay their clusters of e.^gs on 

 the twigs. The last of the moths is 

 usually dead by the end of July, and 

 as there is only one brood, the insect 

 from July to the next May remains in 

 the egg stage. 



In our study of this insect we found 

 that there were several kinds of para- 

 sites that attacked it, both in the larval 

 and pupal stage. The larvae were also 

 subject to disease. Birds and predace- 

 ous insects destroyed some, but it was 

 clear that all these forces combined 

 were not at present sufficient to keep 

 it in check. 



Means of Control. 



Anyone who has ever seen the tat- 

 tered foliage, and the holes eaten in 

 the apples v/ould think that all that was 

 necessary to control this biting pest 

 would be to spray the trees a couple of 

 times with arsenate of lead while the 

 injury was being done. I also had 

 great hopes of success by this method, 

 but, when I tried it I found that arsen- 

 ate of lead, no matter when or how 

 carfifuUy applied, did not kill more at 

 the most than 50%. It often did not 

 seem to destroy even that many. The 

 reason for this is that although the 

 larvae will die, if they eat the poison 

 while thej'' are still small, yet their 

 habit of feeding inside the little webbed 

 leaflets presents most of them from get- 

 ting any of the poison on their food, 

 and later on when they are half an inch 

 or so in length they seem to be able to 

 eat the poison and not be killed. 

 Arsenate 0£ lead does kill some, how- 

 ever, and we strongly advise any one 



troubled with this pest to give the tree 

 two applications of arsenate of lead (4 

 lbs. to 40 gals, of dilute lime-sulphur 

 or bordeaux mixture), the first applica- 

 tion being just before the blossoms 

 open and the second just after they fall. 

 These are two of the regular sprayinga 

 that every apple and pear orchard 

 should receive even if this pest were 

 not present. Both sprayings should be 

 thorough and every leaf, if possible, be 

 covered bolh from above and below. 

 The Best Remedy. 



Scalecide is a miscible oil spray, 

 manufactured by The B. G. Pratt Co., 

 50 Church Street, New York City. It 

 costs about $30.00 per barrel, and 

 should be used at a dilution of 1 gal. 

 to 15 gals, of water, so that one barrel 

 will make 16 barrels of spray. When 

 diluted the spray looks like milk, and 

 is easy and pleasant to use. This or 

 some other good miscible oil is the only 

 substance yet known that will give real 

 good results against the pest. The 

 mixture must be applied just before the 

 leaf-buds burst in spring, and at that 

 date will destroy the eggs or prevent 

 their hatching, but will not do so if 

 applied in the autumn. Great care, 

 however, is necessary to see that every 

 egg mass is thoroughly wet; a mere 

 light mist spray will, therefore, not do. 



In order to save material and make 

 the spraying easier badly infested trees 

 should be severely pruned and the 

 tops, if very high, lowered. In spray- 

 ing we must keep in mind that the egg& 

 are laid on the twigs, and not on the 

 branches, hence the former must be 

 carefully sprayed while the latter, un- 

 less there is San Jose Scale present, 

 may be disregarded. It is very diffi- 

 cult to cover every twig, and so one 

 should examine his work as he goes 

 along and see that this is being done. 

 A strong wind or high pressure to force 

 the spray right through the tree helps 

 greatly. The stronger the wind the 

 better. 



Cultivate. 



Many larvae were found feeding on 

 weeds, clover, etc., and also maay 

 pupae on the ground ; hence we believe 

 that good cultivation and discing 

 throughout June would destroy many 

 larvae and pupae. The last discing 

 should be as deep and as late as is safe 

 for the district. In some districts this 

 would be about the last week in June, 

 in others not until about July 10th. 



Where fruit-growers have many 

 chickens, these could be kept in the 

 worst affected portion of the orchard, 

 and would destroy great numbers of 

 the larvae as they dropped doAvn on 

 their silken threads, or pupae when- 

 ever these were on the ground or on 

 weeds, but poultry would give best re- 

 sults where the orchard was cultivated 

 because they then would see the insects 

 more easilv. 



