322 INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



transforming into adults, known as the fall brood, which lay their 

 eggs upon the young growing wheat. 



Nature of Work. — The maggots work in the stems, usually near the 

 ground, and either kill or so stunt the plants that little or no grain is 

 produced. Infested fields appear yellowish and look very unhealthy. 



Distribution. — This insect was introduced into the State many years 

 ago. It is recorded as occurring in the San Francisco Bay region and 

 south along the coast to Monterey Bay, 234 where it is still quite common, 

 but does little or no damage. 



Food Plants. 235 — Wheat is most seriously injured by this pest, and 

 the damage done to that crop in the central wheat-growing states has 

 been great. It also works upon Agrostis, brome grass (Bromus ciliatus), 

 quack grass and American wild rye (Elymus americanus). 



Control.— Fortunately the ravages of this fly in California have not 

 been great, and it is to be hoped that it will never become a serious 

 pest here. Control is extremely difficult, consisting in burning and 

 plowing under the stubble as soon as the wheat is cut and planting as 

 late in the fall as possible. Early trap crops of wheat are also planted 

 about August. Such crops attract the flies, and after the eggs are laid 

 they are plowed under and destroyed. 



Natural Enemies. — Parasites also play some part in the control of 

 the pest. In the Eastern States the parasite, Merisus destructor Say. 

 works upon it. The internal parasite, Semiotellus destructor, has been 

 bred from the fly in California. 



SYRPHIDvE (Family) 



FLOWER, HONEY OR SWEAT FLIES 



Always among the plant lice are to be found flat, sticky-looking 

 maggots, which are decidedly pointed at one end and do not have 

 distinct head, eyes or legs. These so-called "worms" are the larvas or 

 maggots of flies belonging to the family Sijrphidce, which are commonly 

 called syrphid or flower flies. The larvae vary from the very minute 

 first-hatched maggots to nearly an inch in length, according to the 

 species. They may be dark green, brown, orange, very light or nearly 

 black in color. Those feeding upon plant lice, and herein described, 

 are green with a longitudinal stripe on the dorsum. The mouth is 

 situated at the small end, and all of the food is obtained by puncturing 

 the body walls of the lice and then sucking out the contents. This 

 operation is easily observed in the field. The maggot, firmly supported 

 by the large posterior end, raises itself up and begins to blindly move 

 its mouth end about in quest of food. If it touches a plant louse it 

 immediately lifts it into the air and sucks it dry. This is very rapidly 

 repeated, with very disastrous results to the lice. When the larva is 

 full grown it seeks some sheltered spot in which to pupate. This may 

 be accomplished on the stems or upon the surface of a leaf. The 

 puparium is a long, roundish, or oval body of various colors, showing 

 no signs of life. The fly removes one end (the operculum) of the 

 puparium to escape. The adults are of various colors, but those most 



I'.nl No. 10, n. s.. Bur. Ent. IT. S. Dept. Agric, 1898. 

 Jr. Be. Knt. TI, p. 231, 1000. 



