246 



THE CANADIAN HORTICULTURIST 



October, 1914 



Injurious Garden Insects* 



Prof. P. W. Broderick, Winnipeg, Man. 



INSECTS attack plants in various ways 

 and the nature of the injury caused 

 by them may Ix; very varied. Very 

 often the severity of the attack, particu- 

 larly with those insects which burrow 

 within the tissues of trees and plants, is 

 unnoticed until severe injury is done. 

 Some insects may attack the roots and 

 injure the plant in that way, while others 

 work on the buds or leaves, and by de- 

 foliating it seriously interfere with its 

 development. Serious injury is often 

 done to trees in wind breaks and in our 

 forests by these leaf eating insects. In 

 regions where fruits are grown the grow- 

 er has to contend with the injuries of in- 

 sects which bore into the fruit and cause 

 it to become seriously deformed or to 

 fall and decay. 



While many insects bite the tissues of 

 the plants on which they feed, others in- 

 jure the plants by sucking up the tender 

 juices. These insects, from the nature 

 of their attack are often difficult to con- 

 trol and often do serious injury beforere- 

 medial measures can be applied. 



MBTAMOBPHOSIS 



A study of insect life is interesting 

 from the fact that they display many re- 

 markable habits, and that they undergo 

 a rather intricate development. Through- 

 out their life they may pass through a 

 number of well-defined changes. For 

 instance, a common house fly (Musca 

 domestica) was not always a fly but lived 

 for a time as a maggot under co'nditions 

 most unsanitary. As it develops towards 

 a fly, it rests for a time as a dormant 

 pupae, which neither eats nor moves be- 

 fore it emerges as a full grown fly. The 

 period of time that is required for in- 

 sects to complete their development may 

 vary from a few days, as in the case of 

 our common mosquito, to several years, 

 as in the case of the June beetle. 



In the spring and early summer more 

 or less injury is done to garden crops by 

 inects affecting the roots, the more ser- 

 ious of which are the garden cut worms, 

 which are the larvae of night flying 

 moths belonging to the genus Nocturdae. 

 With tender garden plants, if uncheck- 

 ed ,the ravages of cut worms may be- 

 come serious. 



WHITE GRUBS 



In gardens the work of white grubs, 

 which are the larvae of a large brown 

 Ijeetle known as June Beetles (Lachnos- 

 terna fusca) may often be detected. 

 These insects require from two to three 

 years to complete their development and 

 during their larval period are found feed- 

 ing on the roots of tender garden plants 

 . and grasses. P oultry are fond of these 



•Extract from a paper read at the annual con- 

 vention of the Manitoba Horticultural AsBo- 

 ciation. 



large in.sects and if given an opportunity 

 will destroy large numbers of them. 



WIRE WORMS 



Wire worms are often found in the 

 soil attacking the roots of garden crops 

 as well as field crops. These in.sects, 

 which are of a peculiar amber color, de-. 

 velop into long narrow Ijeetles known as 

 Click Beetles (Agriotes lineatus). They 

 are called Click Beetles because when 

 placed on their backs they turned over 

 with a peculiar clicking sound. Their 

 resistance to poisons makes their des- 

 truction dillicult. Late fall plowing, 

 which breaks up the pupae cells, is an 

 effective way of dealing with them. 



WHITE MACiGOTS 



Every year injury is done to the roots 

 of onions and cabbages by small white 

 maggots. These insects prove to be the 

 larvae of small flies (Phorbia cepatorum 

 and P. Brassicea) about the size of the 

 common house fly. The eggs are laid by 

 the adult insects on the surface of the 

 soil near the roots of young plants. The 

 newly hatched larvae works into the soil 

 and begins burrowing into the roots of 

 the young plants causing a decay. They 

 pupate in the ground and emerge later 

 as flies. In their control rotation of 

 crops should be practiced and a strong 

 growth of plants should be stimulated 

 by the use of such quick acting fertilizers 

 as nitrate of soda. Watering plants 

 every seven to ten days with hellebore 

 solution in the proportion of two ounces 

 to one gallon of water is quite effective 

 in controlling this in.sect. 



Among the insects affecting the leaves 

 of garden crops are the larvae of moths, 

 butterflies and beetles, and the adults of 

 some of the leaf eating beetles. 



OABBAjaE WORM 



An insect common on the leaves of cab- 

 bage is the cabbage worm, the larvae 

 of the imported cabbage butterfly (Pieris 

 rapae.) These larvae, which are of a pale 

 green color, do considerable damage by 

 eating holes in the leaves of the cabbage. 

 They later develop into the pale white 

 butterfly seen flitting about the cabbage 

 fields during the summer. Collecting and 

 destroying refuse lying about the cab- 

 bage fields and spraying the leaves of 

 the cabbage with a solution of white 

 hellebore in the proportion of two ounces 

 to one gallon of water is effective in hold- 

 ing the insect in check. 



BLISTER BEETLE AND POTATO BEETLE 



Leaves of the potato are frequently 

 destroyed by leaf eating insects. The 

 old fashioned blister beetle (Epicauta 

 Pennsylvanica) and the Colorado potato 

 beetle (Leptinastora decembeneata) are 

 frequently found in the potato field. The 



1.1 tier which was first ff»und in the state 

 of Colorado, is particul.'irly destructive, 

 the larvae and adults eating both leaves 

 and stems. There are usually two 

 broods during a season, the second being 

 most destructive. The insect winters as 

 adult beetles, and for this reason all re- 

 fuse should l>e collected and destroyed 

 The spraying of the leaves with arsenical 

 poisons, such as Paris green or arsenate 

 of lead, should be effective in keeping 

 these insects in control. 



CURRANT WORM 



The currant worm or currant saw 

 fly (Nematus ribe.si) is particularly 

 injurious to the garden red currant by 

 r(x;ding on the leaves and completely de- 

 foliating the plant. The greenish larvae 

 which hatch from the eggs laid on the 

 under surface of the leaves, are very 

 active feeders and .soon strip off all the 

 leaves if unmolested. When fully de- 

 veloped they pupate and later emerge as 

 an active four winged fly. They may be 

 controlled by the use of white hellebore 

 in the proportion of two ounces to one 

 gallon of water. 



Diseases o{ Ginseng 



Prof. J. E. Howitt, O.A.C., Gaelph, Oat. 



Sclerotinia disease is widely spread. It 

 is reported as occurring in ginseng gar- 

 dens in Michigan, Wisconsin and Ohio. 

 I have never been able to find it in On- 

 tario, nor have I met any growers who 

 are familiar with it. Although quite 

 widely spread it does not appear to be 

 very destructive, only a plant here and 

 there in the beds being destroyed by it. 



This disease usually appears during 

 wet weather in the spring or early sum- 

 mer. Attacked plants wilt and fall over 

 owing to the rotting of the stem at the 

 base. This rot usually extends into the 

 crown of the root. The rotted stems 

 are soft and white and often covered with 

 a cottony, felty, fungus growth. Black 

 resting bodies of the fungus are often 

 found inside the stem in the pith. The 

 diseased roots become soft and doughy, 

 very watery, and tough, but non elastic. 

 The diseased parts remain white, hence 

 the name White Rot. The fungus 



threads penetrate through the tissues of 

 the root and grow out through the 

 breathing pores (Lenticels), forming 

 tufts of white, felty, fungus growth in 

 which black hard resting bodies devel(^, 

 varying from the size of a grain ot 

 wheat to that of the end of the fingc 

 These lie in the soil and carry the dis- 

 ease over the winter. 



To eradicate the disease remove and 

 destroy the affected plants before the 

 resting bodies have time to form. Soak 

 the soil from which the roots have been 

 removed with a solution of copper sul- 

 phate. 



