388 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
portant is necessary to the most successful control of this insect. In 
addition to this I am convinced that all of the apple trees liable to 
infestation in an orchard should be sprayed in order to prevent any 
migration of the flies from untreated varieties. In any clean-up 
attempt all old derelict trees about the farm buildings should be 
thoroughly sprayed or else cut down and destroyed. 
WILD HAWTHORNS AS HOSTS OF APPLE, PEAR AND 
QUINCE PESTS 
By Walter H. Wellhouse, Ithaca, N . Y. 
The wild hawthorn trees have for many years been recognized by 
entomologists as the native hosts of a number of injurious native in¬ 
sects which now attack the apple, pear and quince, having adopted 
these hosts after they were introduced and cultivated in North Amer¬ 
ica. Among the number may be mentioned the apple maggot, Rhago- 
letis pomonella, the dark apple red bug, Heterocordylus malinus, the 
quince curculio, Conotrachelus cratcegi, the lesser apple worm, Las- 
peyresia prunivora and the woolly apple aphis, Eriosoma lanigera. 
This migration to new hosts has been generally attributed to the 
close botanical relationship which exists between the hawthorns and 
the apple, pear and quince, all four being classed in the apple family. 
Another factor which tends to make these hosts interchangeable is 
their almost identical habitat. This allows insects which are re¬ 
stricted by differences in temperature, moisture, light or soil, as well 
as by botanical relationship, to accept apple in place of hawthorn. 
The native hawthorns grow wild in most of the apple and pear growing 
sections of the country. The planting of orchards in places where 
hawthorns were growing has already initiated a number of new fruit 
tree pests. With the continued extension of agriculture the uncul¬ 
tivated areas where hawthorns grow are still being reduced and their 
insect population must continue to seek substitute hosts. 
The writer has a list of 374 species of insects which have been found 
to feed upon the hawthorns, and 210 of the species are found in the 
United States. Very few of these seem to be permanently injurious 
to the hawthorns and many of them do almost no injury, yet when they 
adopt as a host the apple, pear or quince which has been nursed and 
shielded from hardships so long that it has become tender and non- 
resistant, the injury may become much greater. For instance the 
puncture of the quince curculio in the side of a haw causes no great 
deformation of the fruit but its puncture in the side of a quince or 
pear will cause a marked depression and result in a knotty fruit. 
