THE INSECT FAUNA OF THE GENUS CRATAEGUS 1051 



The apple redbug, Heterocordylus malinus, is another hawthorn insect 

 which has adopted the apple. It was formerly believed that the false 

 apple redbug, Lygidea mendax, was also originally a hawthorn insect, 

 but the observations of Cushman (1916), as well as those of the writer, 

 indicate that L. mendax is a wild-crab insect and does not feed extensively 

 o.n hawthorns. 



The quince curculio, Conotrachelus crataegi, is a very common feeder 

 in haws which has occasionally injured quinces seriously and has thus 

 gained its common name. Likewise the lesser apple worm, Laspeyresia 

 prunivora, has gained its common name because of occasional migrations 

 from hawthorn to apple. 



Baker (1915:10) considers the woolly apple aphis, Eriosoma lanigera, 

 to have been originally an elm-Crataegus feeder which has adopted the 

 apple and traveled around the world with it. The woolly aphis is undoubt- 

 edly common on hawthorns. 



Numerous other native American insects that feed on apple, pear, or 

 quince are included in the catalog of hawthorn feeders beginning on 

 page 1090. 



The possibility that foreign hawthorn insects may be imported and 

 become pests in North America should also be considered. When intro- 

 duced into a new environment away from their natural checks, these may 

 become more important here. Recent examples of this are three small 

 moths imported from Europe the apple and thorn leaf skeletonizer, 

 Simaethis pariana; the hawthorn ermine moth, Yponomeuta padellus; 

 and the lesser bud moth, Recurvaria nanella. These have attracted 

 the attention of economic entomologists in North America as apple and 

 cherry pests, while in Europe they feed commonly on hawthorns. 



Since the catalog of hawthorn insects included in this memoir lists 

 their food plants and the continents where each species occurs, further 

 examples of foreign hawthorn insects that are now in North America 

 may be found there. 



BIOLOGICAL NOTES ON INSECTS FEEDING ON CRATAEGUS, AS OBSERVED 

 BY THE WRITER FROM 1917 TO 1920 2 



ACARINA 



Tetranychidae 



telarius Linn., Tetranychus (Red spider) 



The leaves of all species of Crataegus observed showed attack by 

 Tetranychus telarius. The European hawthorns, however, seem to be 

 more often severely injured by these mites than the native species. The 



2 The insects are grouped according to order and family, and arranged alphabetically by species within 

 the family. 



