Photo from U. S. Department of Agriculture 

 TRAYS IX WHICH TINY FLIES, Schedlus (eGG PARASITES), WERE REARED IX THE 

 LABORATORY AT MELROSE HIGHLAXDS, MASS. 



Each tray is stocked with 1,000,000 gipsy-moth eggs. About 90,000 parasites were reared in 

 each traj- for colonization in the field in 1913 (see also page 66) 



the streets and in the gardens and in the 

 orchards, and the forest attack is becom- 

 ing more and more alleviated by these 

 means. But it is not intended that we 

 should rely upon parasites and diseases 

 alone to protect the forests. Careful 

 studies of the feeding habits of the gipsy- 

 moth in particular have shown that, al- 

 though when full grown it attacks almost 

 all sorts of living vegetation, when 

 young it can live successfully upon but 

 a few plants. It must grow large and 

 strong before it can eat and assimilate 

 the leaves of most trees. A pure stand 

 of pine or any other conifer, for example, 

 cannot be harmed by the gipsy-moth, and 



the same may be said of hickory, maple, 

 chestnut, alder, beech, and of mixed for- 

 ests of these kinds of trees ; but where a 

 mixed forest contains oaks and gray 

 birches, then it will suiter, because these 

 two kinds of trees are the preferred food 

 plants of these destructive leaf-caters. 



It results therefore that practical meth- 

 ods of thinning can often be adopted that 

 will almost perfectly protect a mixed for- 

 est, and experiments have shown that 

 mixtures of chestnut, ash, red maple, pine, 

 and hickory are practically uninjured by 

 the gipsy-moth. In these cases the oak 

 scrub has been cut out and the larger 

 oaks and gray birch have been removed. 



45 



