INSECTS ON GREENHOUSE PLANTS 217 



Hand picking of the larvae, or trapping the moths by placing 

 lanterns in pans of water, seem the most effective remedial 

 measures. For caterpillars on chrysanthemums and sweet 

 peas, hand picking also seems the most practical method of 

 extermination. 



245. Pests which may be kept in check by removing them from 

 the soil. White grubs or May-beetles. White grubs are often 

 exceedingly injurious to many crops. They live in the soil and 

 feed on plant roots. The attention of the writer was recently 

 called to a serious attack of this larva on the roots of cyclamen. 

 They also attack the roots of the rose, carnation and other 

 plants which are usually grown in beds or benches. The life 

 history of the white grub has been worked out as follows : the 

 grubs begin to pupate in the ground in June or July. Later, 

 they change to beetles and remain in the ground through the 

 winter. They feed through a second summer, and the following 

 spring they emerge and feed on the leaves of trees, mate, and 

 lay their eggs in the earth in June or July. These soon hatch 

 into grubs, which remain in this stage over winter. These 

 pests, therefore, may pass the winter in the ground in the beetle 

 stage or in the larval stage. The feeding habits of the two vary, 

 however, for the larvae are the only forms destructive to roots, 

 hence this stage is the one of most interest to the flower-grower. 



246. Habitat. While the larvae are most common in pasture 

 sod, they may be abundant in sod from mown land, and may 

 also occur in soil which has been under cultivation for some time. 



247. Methods of preventing attack. As the flower-grower 

 makes use of large amounts of fibrous sod, it is very probable 

 that the larvae of these pests pass the winter in the compost 

 heap. Field preparation of the soil is, therefore, advisable. 

 There is an opinion among growers that late fall plowing destroys 

 this insect. Scientific observations claim that the grub goes 

 downward in late fall, and may reach a depth of two or two and 

 one-half feet. If this is true, the larger part of the larvae are 

 below the reach of the plow by October. Early in the spring, 

 they come nearer the surface, but the greater part are uninjured 

 by spring plowing or other treatment of the land. However, 

 until further experiments have demonstrated the ineffectiveness 

 of fall plowing for ridding the soil of white grubs, this practice is 

 safe to follow. Swine feed on these larvae, and are recommended 

 as a means of ridding the soil of the pest. 



248. Pests exterminated by poison baits or by hand picking. 

 Cutworms. There are many forms of cutworms, and they 

 belong to different genera. Of these genera, Agrotis, Hadena, 



