530 Scientific Proceedings, Royal Dublin Society. 



antennae folded by the sides. They lie in the normal position. On the 

 application of slight heat, or when disturbed, slow movement begins ; and 

 after the legs and antennae have assumed the normal positions, a beetle may 

 commence to walk or even jump away from the place of hibernation. Even 

 then, however, they are sluggish in movement and readily reassume a 

 quiescent state. 



Hibernation usually occurs in October, or in late September, if the 

 weather is severe. In early October, 1920, the beetles were observed going 

 into hibernation, although individuals were seen on the 19th of October 

 feeding on flax seedlings which were growing in the dug portion of a potato 

 field from seed spilled there. 



12. — Natural Checks and Enemies. 



Various birds were seen to prey on the larvae and pupae when exposed 

 to their view. Some adults become entangled in the webs of spiders placed 

 near the soil, and thus fall a prey to them. A carabid beetle, Bembidium 

 lampros (which Mr. Halbert kindly identified), was seen early in May to 

 attack the gravid females; and by placing three of the latter in a tube 

 containing some small lumps of soil with two of the carabids, it was found 

 that by next day two of the flea-beetles had been devoured. 



It is highly probable that B. lampros is also predaceous on the eggs, 

 although this has never been actually observed. This species of ground 

 beetle was exceedingly abundant in the soil of the experimental plots 

 throughout the 1921 season. 



Larval mites of the family Trombidiidae have been found attached to the 

 adults. One specimen which Mr. Halbert believes to be the larval form of 

 Rhyncholophus ■phalanyeoides was attached to the abdominal tergites under- 

 neath the right elytron. Many mites belonging to the family Tyroglyphidae 

 have been found attacking larvae and pupae in rearing cages ; but their 

 presence was probably accidental, and they cannot be regarded as natural 

 enemies in free life. 



The larvae and pupae appear to be singularly free from the attacks of 

 Hymenopterous parasites. Not a single internal parasite has been reared 

 from the hundreds of larvae and pupae collected outside and brought through 

 to the imago in the laboratory. This would appear to be the general condition 

 in the flea- beetle group. 



13. — Suggestions for Control Measures. 



It is an acknowledged fact that weak, slow-growing seedlings in thin 

 brairds are, for some unknown reason, particularly liable to attack, and, 



