INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



321 



S. H. Essig collected large quantities of seriously infested fruit in 

 Ventura County. 



Food Plants. — The fruits of various species of Opuntia are attacked. 



Control. — Control measures for this pest have not been worked out 

 and will undoubtedly be difficult. The entire elimination of the native 

 food plants should precede any commercial plantings of cactus. 



THE HESSIAN FLY 



Phytophaga destructor (Say) (Family Cecidomyidse) 



[Mayetiola destructor (Say)] 



(Cecidomyia destructor Say) 



(Fi£ 



515) 



Description. — This 

 insect, when fully de- 

 veloped, is a small 

 brown fly, about T V 

 inch in length. The 

 eggs are about 1-50 

 inch long, cylindrical 

 and shining red. The 

 maggots are greenish- 

 white in color and work 

 between the sheaths 

 and stems of the host. 

 The puparia are rich 

 brown and located in 

 the stems or among the 

 roots at the bases of 

 the plants. 



Life History. - The 

 adults appear in the 

 fall and deposit their 

 eggs upon the stems 

 and leaves of the young 

 growing wheat as soon 

 as it is well above the 

 ground. The larva. 1 

 work between the 

 blade-sheath and stem 

 during the fall and 

 winter, changing to 

 puparia in the spring 

 and to adults a little 

 later. These adults, 

 known as the spring 

 brood, lay eggs in the 

 growing stalks, weaken- 

 ing and causing them 

 to fall. After the grain 

 is cut the maggots re- 

 main in the stubble, 

 21— 130G4 



Fig. 315. — The Hessian fly, Phytophaga destructor 

 (Say). Healthy wheat stalk at left and infested stalk 

 at right ; a, egg ; b, larva ; c, puparium or "flaxseed" ; 

 d, exposed pupa; e, adult female laying eggs; f, female; 

 g, male ; h, puparia or "flaxseeds" in natural position 

 between leaves and stalk; i, parasite (Merisus destruc- 

 tor) . Ali greatly enlarged excepting e, which is about 

 natural size. (After Riley, Burgess and Forbes) 



