34 Journal New York Entomological Society. [VoI. xxviii. 



lost. The time of the attack makes a great difference in the devel- 

 opment. If the injury is to a growing region of a biennial plant 

 still in the rosette stage, the plant fasciates during the rosette period, 

 and the growing region becomes linear before the time of the elonga- 

 tion. The stems are then flat from the base. If the plant is adult 

 at the time of the invasion the injuries are in the upper part of the 

 stems which have already completed their first growth. These fas- 

 ciated stems are round below and flat above. In a given field of 

 plants it will also be noticed that most of the fasciated individuals 

 begin to flatten from the same relative point on the axis. This seems 

 to indicate that the banding is stimulated in all of them at the time 

 of the advent of the new swarm, or its less penetrating mode of 

 attack may account for the absence of any degree of fasciation 

 whatever. 



'■ The importance of conditions of culture correlates well with the 

 above observations and the character of the environment is signifi- 

 cant in the production of the fasciation in two ways : namely, in 

 providing a favorable habitat for the insect, and in promoting vigor 

 in the individual plant, such that it will recover from, and not suc- 

 cumb to, the mutilations. Degrees of moisture, isolation, and light 

 all influence the activities of the insect as well as the development of 

 the plant itself. Healthy plants may be more attractive to the 

 insects; damp or rainy weather may drive the insects into the flow- 

 ering heads, or under the young leaves; isolated plants in full sun- 

 light may be better exposed for the hatching of the eggs. An ento- 

 mological study of the habits of these animals would be of interest 

 in this connection, and would throw light on the exact relation of the 

 insect's life-history to the life-history of the plant. There always 

 remains the further necessity that the plant shall be ' susceptible,' 

 but we are assured by de Vries that the degree of susceptibility of the 

 normal and flourishing primrose is superior to that of the ailing 

 plant, and that the physiological responses of the two are not alike." 



Without attempting to explain the relation of insect injury to 

 fasciation in these plants, we wish to state that the " Mompha" re- 

 ferred to by Miss Knox consists of several distinct species, which 

 confine their attacks almost exclusively to certain parts of the plant ; 

 also that these insects belong to the Lepidoptera, the members of 

 which do not possess a true ovipositor and that the eggs of these 



