1050 WALTER H. WELLHOUSE 



feeds on Crataegus, Malus, Sorbus, Quercus, Ulmus, and Corylus, which 

 may all be found in the open-woods community, as may the host plants 

 of the flat-headed apple-tree borer, Chrysobothris femorata Fabr. On 

 the other hand, the leaf beetle, Cryptocephalus bipunctatus Linn., feeds 

 near the streams on such plants as Salix, Betula, Crataegus, and Corylus, 

 and Agrilus vittaticollis Rand, is found along the fence rows on Crataegus, 

 Prunus virginiana, and Amelanchier. No very distinct lines can be 

 drawn between the members of these communities, since many of the 

 plants and insects belong to more than one community. 



THE RELATION OF CRATAEGUS INSECTS TO APPLE, PEAR, AND QUINCE 



A more complete knowledge of the insects that feed on Crataegus is of 

 considerable importance as an aid in the control of insect pests of the 

 cultivated commercial fruits. It has for many years, since the days of 

 Walsh and Riley, been recognized by entomologists as the original native 

 host plant of a number of important insect pests which now attack the 

 apple, the pear, and the quince in the northeastern section of the United 

 States. In all probability new pests must be expected to attack the culti- 

 vated fruits in the future as the population of the country increases, 

 since as a consequence less uncultivated land will remain where the insects 

 may feed undisturbed on their natural hosts. 



The main commercial fruits of the United States, such as the apple, the 

 pear, the quince, and the cherry, are natives of the Old World and have 

 been imported by man into America. With them were imported a number 

 of foreign insects, such as the codling moth, the bud moth, and the sinuate 

 pear borer, which continued to feed on them in this country. Many of 

 the pests now destructive to these fruits, however, are native to North 

 America and are not found in the Old World. Before the extensive plant- 

 ing of the imported fruits these insects must have fed on native plants. 

 Among the most numerous of the native plants which are similar to the 

 apple, the pear, and the quince are those of the genus Crataegus, and the 

 members of this genus are widely distributed throughout many of our 

 commercial fruit districts. 



A young orchard which is set in the midst of hawthorns may be ruined 

 in a few years by the insects that migrate to it from the surrounding trees. 

 Well-established orchards may suffer from the attacks of new pests when- 

 ever there is a failure of the crop of wild haws or a clearing of the land 

 occupied by hawthorns so that their natural guests must seek other 

 hosts. 



It is commonly known among entomologists that the apple maggot, 

 Rhagoletis pomonella, was originally a hawthorn insect and that after the 

 apple had been cultivated in North America for many years this insect 

 selected the larger, juicier fruit of the apple for its home. It is still found 

 in the haws but is now known as an apple pest. 



