ENTOMOLOGY 161 



appearance, sometimes noticeable at quite a distance. The leaves 

 or tops decay if the weather turns wet and the keeping qualities of 

 the bulbs are impaired. 



The immature insects are usually more abundant than the 

 adults, they are about one-twenty-fourth of an inch in size, and yel- 

 lowish-green in color. The body is long and slender, with six legs 

 and six jointed antennae. The feet, like those of all true thrips are 

 destitute of claws. The general color is dirty yellow with dusky 

 markings. The antennae are seven-jointed in the adult. The ex- 

 tremely narrow wings are fringed with long hairs giving them a 

 feathery appearance. The time required for each generation is said 

 to be about six days in the South. Here in Michigan, more time 

 will, no doubt, be required; at any rate, a number of broods are 

 developed each year. 



Thrips feed by scraping minute particles off from the soft 

 parts of the plants, but as far as their control is concerned, they 

 may be classed with the sucking insects, and we must resort to con- 

 tact insecticides to kill them. Kerosene-emulsion, used at the rate 

 of one part of the emulsion to ten of water will kill them. To- 

 bacco water should also prove effective. Drenchings of cold water 

 are said to be useful when practical, for thrips thrive best in a dry, 

 warm atmosphere. (B. 233, Mich. E. S.) 



ONION. 



Onion Maggot. It is very similar in mode of attack and life- 

 history to the Cabbage Maggot already described; it is unnecessary, 

 therefore, to repeat these particulars. It is often extremely destruc- 

 tive, and has almost driven market gardeners to despair. The pre- 

 ventive measures referred to above are hardly suitable for a plant 

 whose style of growth is so different from that of a cabbage, and few 

 persons would take the trouble to protect onion beds with cheese- 

 cloth screens, nor could tarred paper disks be employed. There is, 

 however, a simple method of protection which has been found effec- 

 tive : as soon as the tiny shoots of the onions begin to appear above 

 the soil, the rows should be treated with a whitewash made of lime 

 and watei; and thick enough to form a thin crust over the surface. 

 The effect of this is to close up all crevices and openings in which 

 the parent fly would lay her eggs, and prevent the maggots which 

 may hatch for any eggs laid above ground from reaching the roots 

 beneath. The young plants penetrate through the thin crust of 

 lime without difficulty. 



Later on, when hoeing, any plant that is not growing satisfac- 

 torily should be cut out and crushed underfoot so as to destroy the 

 maggots. Furthermore, onions should not be grown a second time 

 on, or close to, a bed which has been infested with these insects. 

 Pyrethrum insect powder or white hellebore may be applied in the 

 same manner as recommended for the cabbage maggot. Many other 

 substances, such as salt, plaster, Paris green, etc., have been tried 

 without any satisfactory results. When taking up the onions in the 

 fall any bulbs infested by maggots should be carefully destroyed. 



