
Oy ects ical g/L Gontrol 
SOWBUGS 
INJURY. Sowbugs often become so plentiful in the greenhouse that they eat the newly planted 
cuttings at the base. 
CONTROL. Any of the many poison baits will give partial control but a complete spraying with DDT 
under the benches has given excellent control. Deenate 50W will give complete control. 
TARNISHED PLANT BUGS 
The tarnished plant bug or sting fly comes into the greenhouse through open doors and ventilators 
in late summer or early fall and does considerable harm to this crop. Chrysanthemums growing in 
the open are frequently affected. Varieties such as Mary L. Hall and Sea Gull are attacked to a 
greater extent than other varieties. 
INJURY. It has sucking mouth parts and obtains its food by inserting its long, slender beak into the 
plant tissues and sucking up the contents of the injured cells, apparently injecting saliva, which 
causes the death of the tissue in the immediate vicinity. The stem is often slightly bent and the 
terminal growth is malformed because of this injection. 
CONTROL. Early morning spraying or dusting with any of the pyrethrum materials will kill those 
bugs that are present but this will have to be done each day for complete eradication. Deenate 
50W has been giving fair control but again this insecticide is best used as a contact. Parathion 
fumigation will control this insect in the greenhouse. 
THRIPS 
The chrysanthemum is usually attacked by one or more species of thrips. These small, narrow-bodied, 
active insects which range in color from yellow to brown or almost black, injure both the leaves and 
the blossoms. 
INJURY. Thrips have mouth parts that are fitted for piercing and scraping the leaf surface and for 
sucking the juices and other cell contents. The upper surface of the foliage is covered with whitish 
blotches while minute black specks appear on the lower surface. Unless a constant watch is kept 
on the plants, and control measures properly executed, thrips are capable of causing severe injury 
within a short time. 
CONTROL. Deenate 50W used at the rate of I-1!/. pounds to 100 gallons of water is a very effective 
control. Other insecticides containing Benzene Hexachloride are also recommended. Parathion 
will control the chrysanthemum and onion thrips. 
25 

Tarnished Plant Bug Thrip Injury 
