1050 + WattTeR 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. 
