No. 6. DEPARTMENT OF AGRICULTURE. 531 



tions (See Insecticides, B.), which kill by entering the breathing 

 pores, but not the mouth. 



THE SPECIES OF INSECTS. 



ORDER PHYSOPODA: Family Thripdae: Thrips. (Fig. 4.) 



Tobacco Thrips or Onion Thrips ( Thrips tabaci). 



The Thrips are among the most minute of insects. Their mouth- 

 parts are fitted partially for suclving and partially for biting, but 

 mostly the former. They do not eat away tlie tissues of the plant, 

 but pierce the leaves and cause small white specks which may become 

 so abundant as to give the plant a grayish appearance. These in- 

 sects are from one-sixteenth to one-fortieth of an incli long and 

 about one-fifth as wide. They are dark in color and have four very 

 minute wings fringed with long hairs which increase their surface 

 firea and fiying capacity. When disturbed they suddenly disappear 

 by jumps or short flight. 



This species has been reported feeding on sixteen species of plants, 

 besides on melons, squash and cucumbers; mostly on onions and 

 cabbage, where they are at times very destructive. 



Their habit of sudden jumping flight gives the key to the remedy 

 for them, which is Mechanical Device No. 3. They will fly down 

 the wind and be carried against the tarred cloth or board held in 

 their path of flight to the leeward. They can of course be killed by 

 contact applications; also by Mechanical Device No. 3 and by in- 

 secticides 6 to 12. 



ORDER HEMIPTERA: The True Bugs, Plant Lice, Scale Insects, 



Etc. 



FAMILY COREID^E: The Squash Bugs. (Fig. 5.) 



The Squash Bug or ''Stink Bug" {Anasa tristis). 



The squash bug is about five-eighths of an inch long and one- 

 fourth of an inch wide, with antennte half the length of the body. 

 The head is dusky, nearly black; thorax or part to which the wings 

 are attached, dark brown; scutellum or triangular piece between the 

 wings, dusky; sides of abdomen or posterior part banded with six 

 yellowislh bauds; upper wings dark and brown or grayish at basal 

 half and sooty black toward the tips, which are thinner; the under 

 wings are smaller and very thin and gauze-like toward the base and 



