THE INSECT FAUNA OF THE GENUS CRATAEGUS 1069 



sufficient to say that A. nebulosus is a brown or grayish oval beetle, from 

 3.75 to 4.25 millimeters long, generally with a whitish, V-shaped .mark 

 on the fore part of the elytra, with a long, slender, curved beak, and the 

 front femur having two teeth on its apical part, one large and the other 

 small (Plate LXXIV, page 1070). 



The species has been found in New York, New Jersey, Michigan, 

 Indiana, Missouri, Arkansas, and Louisiana, and therefore it seems 

 probable that it is present wherever its hosts are found east of the Rocky 

 Mountains. Although Dietz considers this species to be more charac- 

 teristic of the European fauna than of our own, no record can be found of 

 its occurrence in Europe or elsewhere outside of this country. 



Its hosts include a number of the larger-flowered species of hawthorns, 

 such as Crataegus punctata, C. brainerdi, C. pruinosa, and C. mollis. The 

 smaller-flowered species, such as C. oxyacantha, are not selected by the 

 beetles for oviposit ion, probably because there is not space enough for 

 the full development of the larva within the bud. 



The injury caused by the hawthorn blossom weevil is most apparent 

 while the trees are in full bloom. At that time the infested blossoms are 

 brown and remain closed. On badly infested trees fully fifty per cent of 

 the blossoms may be in this condition and the trees present a scorched 

 appearance. As the young fruit begins to set, the infested blossoms com- 

 monly fall to the ground, but they may sometimes be seen on the trees 

 even after the beetles have emerged in June. 



The beetles come out of hibernation and appear on the branches of the 

 hosts about mid-April, feeding ravenously on the buds, which are showing 

 green. It is not uncommon to see a beetle with feet braced and beak 

 inserted up to the eyes in a bud while it hurriedly eats the tender leaves 

 within. As soon as all the food within reach of the entrance hole is eaten, 

 the beetle seeks another bud on the twig and repeats the process. The 

 puncture in the bud is round, is 0.3 millimeter in diameter, and turns 

 dark as 1 soon as the beak is withdrawn. The presence of the beetles may 

 be detected by these dark round holes in the buds before the egg-laying 

 period arrives. The beetles continue to feed on the buds during suitable 

 weather until the clusters have separated enough for oviposition in the 

 blossoms. 



During cool weather the beetles remain inactive, generally in the axils 

 of the twigs with their heads down. A few observations on the relation 

 of temperature to their activities were made, and these indicate that 

 the beetles remain inactive while the temperature is below 50 F. The 

 optimum temperature is from 60 to 70, and when it is raised to 78 

 the beetles rush about like mad, attempting to oviposit in every bud. 

 Under most conditions they seem reluctant to fly, but when placed on 

 distasteful food they fly away. They continue their activities on cloudy 

 or rainy days and at night if the temperature is sufficiently high. 



