Jan. IS, 191S Agrilus Bilineatus 287 



the day, and their feeding habits as observed in the insectary, indicate the 

 probabiHty that the early part of the day is ordinarily spent in this way. 



It was definitely proved that the adults of Agrilus bilineatus feed on 

 the foliage. They usually eat around the margins of leaves, but also 

 tear off the epidermis and sometimes eat nearly the entire leaf, including 

 the midrib. Plate XXXIX, figure i , shows a leaf on which four beetles 

 had fed for 24 hours. They even ate the edge of a paper bag which was 

 on the floor of the insectary, where most of the obsers'a tions were made. 



The difficulty of observing the feeding in the field was increased by the 

 protective habits of the beetles. The flight to and from leaves or logs 

 and tree trunks was ordinarily quite direct, but in some cases they hov- 

 ered before lighting. When disturbed, however, they flew rapidly in a 

 zigzag manner, which is probably of protective importance, as under 

 such conditions it is almost impossible to follow them even with the eye. 

 If they are startled while at rest, they fold their appendages and drop 

 to the ground, feigning death. They dodge from side to side very quickly 

 and run rapidly over any kind of surface. On one occasion a beetle was 

 watched walking about inside a glass tube. It experienced no difficulty 

 unless it tried to walk upside down upon the slippery concave surface, 

 when it began to lose its footing. This was evidently not a new occur- 

 rence, for it immediately put one of its front tarsi to its mouth and ap- 

 parently moistened it; it then reached this appendage back to rub it 

 against the posterior ones. When all the tarsi had been treated in this 

 way, the beetle ran about until it began to slip again, when the process 

 was repeated. 



On sunny davs during the entire season males and females were court- 

 ing and mating. These performances were often noticed on logs or 

 woodpiles and on the foliage of small plants at the base of trees, as well 

 as on tree trunks. The courting was usually abbreviated and sometimes 

 wanting. Males were seen to fly from the air directly to females on the 

 tree. At other times a male was seen to side-step to within an inch of a 

 female and then spread its wings as if to fly before advancing farther. 



In one case a male stood near a female until she finished ovipositing 

 and then mated with her. But it was not always the males that made 

 the advances, for it was not uncommon to see females courting males, in 

 which case they often found themselves ignored. In mating, the sexes 

 were together from 2 to 1 2 minutes, with an average of about 4 minutes. 



The females were ovipositing from June 19 to July 13. No record 

 of ovipositing was obtained before 1 1 a. m. and but one after 5.30 p. ni. 

 While it was not so common to see females actually ovipositing, they 

 could be seen nearly all the time during the hours of activity with their 

 ovipositors out searching for places to oviposit. They laid the eggs in 

 the bottoms of cracks, but not every crack was suitable. The females 

 went carefullv along, using their ovipositors as tactile organs, exploring 

 everv crevice. The insect often appeared to be in a great hurry and 



