GLADIOLUS THRIPS 
 
 MXRY F. BENSON 
 
 a. Adult thnps: b, egg; c, larva; d, pupa (or resting stage); e, foliage 
 and flower spike showing typical feeding injury; /, uninjured gladi- 
 olus corm; g, corms injured by feeding of thnps, showing charac- 
 teristic russeted appearance, (a, b, c, and d about 20 times natural 
 size; e, /, and g about one-halt natural size.) 
 
 (See other side for life history and control) 
 
 Bureau of Entomology and PUnt Quarantine 
 States Department of Agriculture 
 
 Picture Sheet No. 6 
 
GLADIOLUS THRIPS 
 (Taeniothrips simplex Mor.) 
 
 Life I listen 
 
 The gladiolus thrips overwinters on the stored corms, where feed- 
 ing and reproduction are continuous as long as the temperature Is 
 above 50° F. During the growing season the foliage and (lowers of 
 
 the growing plant are attacked. The eggs are inserted in the plant 
 ti>sue. Under favorable conditions a generation of the thrips may he 
 completed in 2 weeks or less. The larvae and adults are responsible 
 for tin' injury; no feeding occurs in the pupal stage. 
 
 Control 
 
 This thrips is subject to chemical control, either on the stored 
 corms or on the growing plants. Very often both types of control 
 measure's may be used. 
 
 Control on the Corms 
 
 On dormant corms the thrips may be eliminated by the use of 
 naphthalene (lakes. Apply the flakes at the rate of 1 ounce per 100 
 corms and leave them with the corms for 4 weeks at a temperature of 
 ()()° to 70° F. The conns may be contained in paper sacks, or in bulb 
 trays or boxes covered with paper. Do not use naphthalene on non- 
 dormant corms. If late spring treatments are necessary, soak the 
 corms for 12 to 24 hours in a solution of 1 ounce of mercuric chloride 
 (corrosive sublimate) in 7}i gallons of water, in an earthenware or 
 wooden container. 
 
 Control on the Plants 
 
 The growing plants should be watched for evidence of thrips 
 feeding; and if such feeding is noted, spraying should be begun at 
 once and continued at weekly intervals until flowering. If infested 
 plants are not sprayed until blooming, the (lowers cannot be saved. 
 The spray should be applied as a fine mist, and an effort made to 
 avoid run-off. 
 
 The recommended spray combination is as follows: 
 
 Small Large 
 
 quantities quantities 
 
 Tartar emetic. - 1 ounce. 2 pounds. 
 
 Brown sugar.. 2 ounces. I pounds. 
 
 Witter 3 gaUons. LOO gallons. 
 
 16 20760 
 
 UNIVERSITY OF FLORIDA 
 
 3 1262 09082 4649 
 April 1941 U.S. Government Printing Office 
 
 For Bale by the Superintendent of Documents, Washington, I). C. Price 5 cents