194 Journal of Agricultural Research voi. xxii, no. 4 



part laid on the ground in the wire cages for wet seasoning. The con- 

 dition of the wood on which the insects were first found ehminated the 

 use of certain of these periodic cuts and conditions of seasoning. How- 

 ever, the first-year adults were usually caged with the choice of many of 

 these cuts and the one infested most heavily was considered as the 

 optimum condition and used afterwards for continuation of the succes- 

 sive broods. The optimum cut could only be determined when sufficient 

 material was given for the number of insects present, as an unfavorable 

 cut may be attacked when the adults are confined on it without sufficient 

 optimum material. 



Wood used a month or two after being cut is spoken of as green or 

 freshly cut material. 



In many cases wood from several individual trees was used to avoid 

 any possibility of offering an undesirable individual. 



To illustrate the variation in optimum conditions of wood, several 

 examples are given: Callidium antennatum Newm. requires wood dry- 

 seasoned over winter; Neoclytus capraea, wood cut during the late winter 

 with the inner bark still sappy ; Liopus alpha Say in hickory, twigs cut 

 in the early fall, air-seasoned for a while and then left on the ground 

 over winter so that the inner bark sours somewhat. (This condition is 

 brought about by the girdling habit of Oncideres cingulata Say.) 



Several terms which may need explanation are used in reference to 

 the species of host wood: Primary host, or original host, refers to the 

 wood in which the insect is found in nature and first caged in these experi- 

 ments ; as secondary host is understood wood in which a colony has been 

 successfully produced in the experiment, but it may or may not be 

 recorded as a host in nature; an unfavorable host is one not recorded 

 from nature and in which attempts to produce a colony have not been 

 entirely successful. 



All experiments conducted are here given, although a few have been 

 unsuccessful or have given no results. Occasionally failure to continue 

 a colony is recorded. In all cases an explanation can not be given. It 

 may be because of an improper cut of wood or of a peculiarity of the 

 individual host. In one case partial failure was due to a nematode 

 parasite causing sterility of the females; in another, the parent insects 

 were entangled in spider webs and killed before ovipositing. 



Reference is made to larval transfers from one host to another. This 

 is accomplished by making a smooth cell through the bark of the new 

 host, partially filling it with frass from the larval mines of the original 

 host, then placing the larva in this cell and finally tightly fixing a piece 

 of bark over the cell. Such transfers do not injure the larva or affect 

 its development. Many cases of transfer to the same host resulted in 

 the survival of every larva. 



These experiments were conducted at tlie Eastern Field Station, East 

 Falls Church, Va., and all flight dates of the adults and times of cutting 

 of the wood refer to this locality unless otherwise stated. 



