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The Florists' Review 



17 



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SAVING MUMS FROM MIDGE 



PEST DANGEROUS IN JUNE. 



How to Recognize It. 



"How does the chrysanthemum 

 midge look?" asks a subscriber. If 

 you read the article in The Eeview for 

 January 1, 1920, which first warned 

 the trade of the midge, and the further 

 article in the issue of June 17, 1920, 

 you are adequately informed by illus- 

 trations and descriptions, so as to be 

 able to recognize the pest when it makes 

 its appearance upon your plants and to 

 combat it intelligently. 



The insect itself, as it appears in the 

 adult stage, is a tiny fly and its length 

 is about equal to the diameter of an 

 average pinhead, while its width is 

 about one-third of its own length. In 

 the earliest stage of its life its color 

 is the same as that of the leaf. In mid- 

 dle age it is somewhat yellow, but about 

 the time that it leaves its harbor it is 

 a reddish color. It is exceedingly hard 

 to sec. 



Habits Show Means of Control. 



The midge has two fleecy wings, 

 which are apparently not used for the 

 purpose of flying, but rather as an aid 

 in balancing itself upon the leaf of 

 the plant. When the pest comes forth 

 from the egg it leaves a bit of fluff on 

 the sides of the hole in the leaf from 

 which it emerges. It rarely migrates 

 from one i>lant to another, and several 

 generations of females are often found 

 on one plant. The male, however, does 

 go from one plant to another to some 

 extent. The insect is short-lived. The 

 life of the male is much shorter than 

 that of the female. In 

 the latter, life is sustained 

 as long as from two to 

 five days. 



It is extremely impor- 

 tant to know the habits 

 of the insect, in order 

 that, when it is found to 

 exist in the greenhouse, 

 it can be intelligently 

 combated and finally ex- 

 terminated. The damage 

 to the plants is not done 

 by the insect itself, but 

 it is the container of the 

 eggs which reduces the 

 commercial value of the 

 plants and flowers. Imme- 

 diately upon emerging 

 from the egg, the insect 

 mates and Jacgins to lay 

 its eggs, producing from 

 eighty to 150 eggs and 

 dying a natural death be- 

 fore it is forty-eight hours 

 old in some instances. As 

 far as can be ascertained, 

 during the warmer months 

 the hatching period of 

 the eggs is from eleven 

 to eighteen days; during 

 the winter months the 

 eggs may remain in the 

 plant from three to five 

 months, depending upon 

 the temperature main- 

 tained in the greenhouses. 



Freezing does not affect the viability 

 of the eggs in the least. 



In laying the eggs the female pushes 

 them into the soft part of the leaf; the 

 growth of the plant is rapid and wher- 

 ever a number of eggs are buried there 

 is a scar on the leaf or stem. Instances 

 are not uncommon of the presence of 

 as many as fifty eggs on one leaf. 

 Under these circumstances, it is not 

 hard to understand why the plant is 

 often badly crippled and undersized. 

 Sometimes the bloom, if it appears at 

 all, will open sidewise and perhaps turn 

 down instead of up. 



The eggs hatch between midnight and 

 2 a. m., and it is at this period that 

 measures for the extermination of the 

 insect are most effieacious. The time of 

 the insect's emergence from the shell 

 is the only time at which it is exposed 

 and can be killed before it has a chance 

 to lay its eggs. 



Effective Measures. 



The most effective means of combat- 

 ing the insect is the nicotine spray. As 

 stated above, the insect lays its eggs 

 in the soft parts of the leaf or stem 

 of the plant. In laying the eggs the 

 insect will puncture the leaf, in order 

 to push the eggs within it, and, if the 

 leaf is covered with a coating of nico- 

 tine, the midge must necessarily punc- 

 ture this coating before it reaches the 

 leaf. As a result, it will die before ac- 

 complishing its purpose. The spraying 

 should be done at least every twelve 

 hours to be effective. In regard to the 

 strength of the mixture we will speak 

 later. 



Hydrocyanic acid gas is also an ef- 



Thc White ''Warts" House Eggs of the Mum Midge 



fective means of stopping the nefarious 

 work of this pest. But it must be re- 

 membered that if the gas is used, it 

 must be applied at about the time the 

 insect emerges from the egg and in suf- 

 ficient quantity to permeate thoroughly 

 the air around the plant. As stated 

 above, the eggs of the insect hatch be- 

 tween the hours of midnight and 2 a. m., 

 and if the air of the greenhouse is filled 

 with the gas at this time, the insect 

 will be killed before it has a chance to 

 lay its eggs. 



Tobacco dust will help to keep the in- 

 sects down, but will not clean them out, 

 as does the nicotine solution. The hy- 

 drocyanic acid gas will not exterminate 

 the pest unless it is applied every few 

 days, or so persistently as to reach them 

 at a time when they are unprotected. 



Appearance of Egg Housings. 



The presence of midge is readily 

 recognized by the protuberances or 

 ' ' warts, ' ' as shown in the accompany- 

 ing illustration, which form on the leaf 

 or the stem of the chrysanthemum plant. 

 These so-called "galls" are cone- 

 shaped and project obliquely. When 

 fully developed the projection is about 

 one-twelfth of an inch long, and it 

 usually occurs on the upper surface of 

 the leaf. If the insect has already 

 emerged from its egg, a small hole in the 

 leaf or stem of the plant will be found, 

 from which the insect came out. If some 

 of the leaves of the plants are partly 

 crippled, or if light green or white spots 

 are found on the leaves, you have a good 

 example of the midge. If these light 

 spots are opened carefully with a sharp 

 knife, a soft substance 

 will be found, which is 

 the egg of the midgo. If 

 the egg is almost ready to 

 hatch, its color will be 

 reddish and the egg will 

 have a soft shell. When 

 the insect emerges from 

 the egg it is a fully de- 

 veloped adult, and it 

 mates immediately. 



The various preventive 

 measures are well sum- 

 marized in the Depart- 

 ment of Agriculture bul- 

 letin No. 833, as follows: 

 "From the life history it 

 is clear that certain 

 points must be kept in 

 mind if the best practical 

 results are to be secured. 

 First, several generations 

 are always present in 

 greenhouses during the 

 spring and fall occur- 

 rences; second, the adults 

 emerge and mate during 

 the early morning hours 

 and egg laying quickly 

 follows; third, prelimi- 

 nary control experiments 

 show that the egg stage 

 may be controlled by 

 means of spraying or dip- 

 ping the cuttings or 

 jtlants; fourth, it has been 

 demonstrated that the 



