44 SMITH'S CHRYSANTHEMUM MANUAL, 



They deposit eggs in all parts of the plant where the growth is young 

 and tender ; upon the leaf and leaf stems, the stem of the plant, the buds 

 and even on the subterranean shoots or root stalks, provided, of course, 

 these are exposed to the ah-. Their molestations are confined to the 

 Chrysanthemum family, including the section which Florists are most in- 

 terested in, as well as the garden kinds. In aggravated cases they become 

 very numerous, stems and foliage are literally covered with these little 

 galls, which intercepts the natural development. They become stunted 

 and distorted and if allowed to go unchecked they will produce few if any 

 cuttings for propagation. 



While hand picking the affected leaves and stems and burning the 

 tefuse will be helpful in cases where there are so few as to give slight 

 concern, it cannot be considered a complete remedy. The surest and best 

 method is to fumigate either with some form of nicotine (tobacco) or 

 Hydro-cyanic acid gas, thus destroying the fly before it has deposited 

 eggs. 



Either these agencies, used the same as recommended for Aphis, on 

 page 42, will be effective 



From the most eminent entomologists we learn the life cycle of this 

 insect ; as near as can be determined is from 20 to 30 days, that is from 

 the time the egg is laid until the adult is developed and ready to repeat 

 the operation. 



Here we wish to impress upon the reader that while thirty days may 

 cover the life cycle, this period is not of sufficient duration to give assur- 

 ance of clean stock even though continuous fumigations have been main- 

 tained. Our experience teaches us that where the stock plants are kept 

 at a temperature below 50 degrees the development is very much retarded, 

 and where freezing point is maintained the state of hibernation may be 

 continued for several weeks, so that frequent examinations of the plants 

 and the cuttings taken therefrom should be continually resorted to. 



If the foregoing is true, the life cycle depends upon conditions during 

 the stage of incubation and should be fully considered before there is any 

 abatement in the process of elimination. When we consider that the 

 female is capable of laying a hundred or more eggs, it is evidence of the 

 importance to keep a close watch the year around for the slightest mani- 

 festations, and all employees should be instructed to report their presence 

 when detected. 



Why we wish to emphasize the importance of not discontinuing fumi- 

 gations to soon, we beg to call attention to the fact that in 1918 we were 

 convinced our stock was entirely free from this pest, but upon transferring 

 the old plants to new quarters we still found approximately a half dozen 

 which showed a few galls. This leads us to believe that fumigations 

 at least twice a week should be continued throughout the summer months. 



At the return of longer days, more sunlight and higher temperature 

 under glass, the more rapid the development, both in the transformation 

 of the larvea and the activities of the females, a similar period exists as 



