December, 1915. 



THE CANADIAN HORTICULTURIST 



371 



Common Vegetable Crop Insects and Their Control* 



Arthur Gibson, in Charge of Vegetable and Field Crop Insect Investigations, Department of 



Agriculture, Ottawa 



THE Entomological Branch of the 

 Dominion Department of Agri- 

 culture has recently been con- 

 ducting important experiments in the 

 control of such serious pests of the 

 market gardener as cutworms, root 

 maggots, and locusts. Vegetables of all 

 kinds suffered severely from cutworms 

 •during 1915. In Eastern Canada the 

 species which caused most destruction 

 were the Red-backed Cutworm, the 

 Striped Cutworm, and the Dark-sided 

 Cutworm. The habits of these species 

 are similar, and all are surface-feeding 

 cutworms. 



During the past season the poisoned 

 bran remedy, as recommended in our 

 bulletin, "Cutworms and Their Con- 

 trol," with fruit added, as recom- 

 mended for locusts, was used in our 

 experiments near Ottawa, and out- 

 breaks of cutworms quickly controlled. 

 In one large field of onions, where the 

 cutworms were especially abundant 

 and destructive, a single application oi 

 the poisoned bait stopped the outbreak, 

 and no further injury by these insects 

 took place. The twenty pounds of bran 

 mixture has been found sufficient to 

 treat about three acres. The poisoned 

 bait should be spread thinly in order to 

 destroy the greatest number of cut- 

 worms, and when thus spread there is 

 no danger of birds, poultry, or live 

 stock being poisoned. A single poisoned 

 flake of bran is sufficient to kill a cut- 

 worm. 



•A paper submitted at th« recent convention 

 in Toronto, of the Ontario Vejretable Growers' 

 Association. 



Like the old poisoned bran bait, the 

 new mixture containing fruit juice 

 should be distributed over the land in 

 the early evening, so that it will be in 

 the best condition to attract the cut- 

 worms when they come out to feed at 

 night. This new poisoned bait is a 

 cheap, reliable remedy for cutworms, 

 and should be promptly used by every 

 grower on the first sign of injury. If 

 the cutworms are known to be present 

 in the land in the spring, it is a wise 

 precaution to scatter the poisoned bait 

 after the ground has been worked, aiid 

 several days before seeding or plant- 

 ing. 



In widespread infestations of cut- 

 worms in 1915, we observed that the 

 eggs had been laid during the late sum- 

 mer of 1914 on weeds or other plants 

 growing on higher locations and left 

 standing, and that the cutworms which 

 hibernated nearby in their younger 

 stages migrated in May to other parts 

 of the field where food was in plenty. 

 The importance of keeping down 

 weeds and other useless plants, so that 

 the cutworm moths will not be at- 

 tracted to the land for egg-laying pur- 

 poses, is therefore very important. If 

 in spring the cutworms are noticed to 

 be working chiefly on the higher eleva- 

 tions, large numbers may be destroyed 

 before they begin to migrate by prompt 

 application of the new poisoned bait. 

 Root Maggots. 



We have this year continued our ex- 

 periments on the control of root mag- 

 gots, and have again thoroughly demo)i- 



strated the value of the felt tarred 

 paper discs to protect cabbages and 

 cauliflowers. In one field near Ottawa, 

 owned by a prominent market gar- 

 dener, we placed these discs around 

 about 1,600 plants at the time of plant- 

 ing. Before this planting the grower 

 had lost a large percentage of his early 

 cauliflowers, and even after we applied 

 the discs to the second planting of 1,600 

 plants, many plants in adjoining rows 

 ^ were rendered useless owing to attack 

 by the maggot. Of the 1,600 plants 

 above mentioned, practically the whole 

 number were protected from the mag- 

 got. This was an excellent demonstra- 

 tion of the value of the disc, and will 

 lead many of the Ottawa growers to 

 adopt this form of protection next year. 

 It is practically the only satisfactory 

 remedy which we have for protecting 

 cabbages and cauliflowers from the 

 ravages of root maggots. 



Experiments were also conducted 

 with a poisoned bait spray to attract 

 and kill the adult flies before they de- 

 posited their eggs. This work, how- 

 ever, we hope will be continued next 

 year. In Wisconsin a poisoned spray, 

 which has been used successfully to kill 

 the Onion Maggot Fly, is made in the 

 proportion of five grains of sodium 

 arsenate dissolved in a gallon of boiling 

 water, into which is thoroughly mixed 

 one pint of molasses. This mixture is 

 applied as a coarse spray of large drops 

 once a week in strips across onion fields 

 throughout the suznmer. It is claimed 

 that the results show almost perfect 

 control of the insect at a cost of froDi 

 fifty to seventy-five cents an acre for 

 summer treatment. At Ottawa this 

 year we also continued our experiments 

 with various mixtures applied by means 



The devc.o.a..a ti.at ,.s taking piace in the fruit '"dust^ry ^in^New «-- wicjc_^f,'n^^icated^by the ...e of this nursery at A.bert. N. H., which con- 



