320 



[NJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



are white al first, bul soon become light brown and arc about fehe same 

 length as the maggots. 



Life History. — Tlic life history of this insect has not been studied. 

 The winter is probably passed in the pupal stage in the soil or in the 

 fruit. The eggs are evidently laid on the outside of the fruits when 

 the latter are quite small and the maggots upon hatching enter the 



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trjjO'--' jSi 



-. 



Fig. 314. — The cactus-fruit gall-fly, Asphondylia opuntiw Felt. Cactus fruit 

 showing pupal cases and holes where adults have issued. Adults in upper right 

 corner, enlarged tliree times. Fruit natural size. Specimens collected at Ventura 

 by S. H. Essig. (Original) 



pulp, riddling it with holes. Hundreds may infest a single small fruit. 

 Pupation takes place in the burrow just beneath the outer skin. "When 

 ready to change to adult the pupa cuts a round hole through the skin 

 and wriggles from one half to three fourths its length outside before 

 the puparium breaks and the fly emerges. The illustration (Fig. 314) 

 shows the large number of pupae eases still adhering to the fruits. 



Nature of Work. — The first evidences of the presence of this fly is 

 the prematurely yellowing and ripening or the stunting and deform- 

 ing of the fruit. By the time the pupae begin to show through the 

 skin the fruit is entirely destroyed. Because of the possibilities of 

 growing cactus fruits in the southern part of the State, this fly is of 

 considerable economic importance and may become more so as the 

 industry is developed. 



Distribution. — The cactus-fruit gall-fly has a wide range throughout 

 the southern part of the State. It has been reported from Los Angeles 

 southward by Hunter. Pratt and Mitchell. 288 In the spring of 1914 



-" 3 Bul. No. 113, Bur. Ent., U. S. Dept. Agric, pp. 34-35, 1912. 



