CHEYSANTHEMUM MIDGE. 11 



the yolk then takes place, an equal portion being present in each seg- 

 ment. At this stage the pigment takes up a posterior position. , 

 Finally the complete outline of the larva is visible through the shell. 

 At this stage the darker head and mouth parts can be seen, and the 

 previous yolk material appears as a chainlike formation which ex- 

 tends from the anterior to the posterior end throughout the entire 

 inner or central portion of the body. Distinct segmentation is now 

 clearly visible. 



Hatching. — Borden observed the larva when hatching to break 

 from the eggshell by a small cap at one end. Complete development 

 of the larva and pupa takes place within the gall. 



LARVAL AND PUPAL STAGES. 



The larva or maggot upon hatching moves about on the surface 

 among the plant hairs for a period of from 1 to 3 days, preparatory 

 to boring into the tissue. It varies in color from a transparent white 

 to pale orange when seen with the aid of a binocular just after boring 

 beneath the epidermis. On February 2, 1918, H. F. Dietz observed 

 larvae, which hatched from eggs laid four days previously, boring 

 into tissue. (10 X eyepiece, 24 mm. objective, binocular.) The 

 observations were as follows : One larva which was found half buried 

 in the tissues of the stem was timed until it disappeared. It required 

 12 minutes for complete disappearance. During this period the 

 larva moved back and forth with an irregular spiral movement, 

 about 30 seconds being necessary for one complete movement back 

 and forth. Several larvse were then observed beginning to bury 

 themselves, but the operation was interrupted and discontinued, the 

 interruption being caused by another larva which was slowly crawling 

 about in search of a suitable place to "dig in." One of these larvae 

 was observed crawling slowly about for approximately 3 minutes. 

 The bright red pigment of the posterior third of the body is very 

 characteristic at this particular stage. 



As a result of the larva boring into the tissue, an irritation is pro- 

 duced which results in the production of swellings or galls on the plant 

 containing the developing larvse and pupse. 



No molts have been observed from the time of hatching to the time 

 at which the larva is seen entering the tissue. The larva lies bathed 

 in a fluid within the gall. The fully developed larva is of an orange 

 color. 



The female pupa is usually orange colored with the head, thorax, 

 legs, and wing pads nearly black, while the male may be of a lighter 

 or straw color. Formation of the pupa takes place about two weeks 

 from the time the egg is hatched. It is white at first with only a 

 slight brown tinge about the head, but later the head, thorax, wing- 



