June, '15] 



SEYERIX-SEYERIX: IMPORTED OXIOX FLY 



347 



many of the onion fl}' puparia and expose others to the sunshine and 

 these, in all probability, would fail to hatch. Many puparia would 

 probably be destroyed by natural enemies, such as birds and Carabids. 



V PoisoxED Bait Spray 



Although seYenty methods of fighting root maggots haYe been put on 

 record, no attempt has been made to poison, with a sweetened spray, 

 the adult before the egg-la^-ing period begins. Under natural condi- 

 tions the imported onion flies were obserYed feeding on wild and 

 cultiYated flowers, onion leaYes and soil. In captiYity Phorhia cepeto- 

 rum relished diluted black-strap molasses, and they fed upon this 

 sweetened liquid until their abdomens became greatly distended. If 

 this insect is attracted to diluted molasses under natural conditions, 

 the greediness of the flies for this sweet when poisoned, would be the 

 weak point in the life history to attack the pest. If this poisoned bait 

 be applied in the form of a spray to the onion leaY^es when the imagoes 

 first appear on the wing and if the Anthomyicls were to feed upon the 

 insecticide no doubt large numbers would be killed before the egg- 

 lajing period commences. 



A series of experiments were performed to determine the length of 

 time that the imported onion flies would Hyc in captiYity when fed with 

 diluted black-strap molasses to which had been added different kinds 

 and amounts of insoluble poisons. Some of the flies were still aliYC at 

 the end of a week in these experiments even though the poisoned bait 

 was applied daily T^dthin the jars. The folloT^-ing proportions of 

 molasses and water were used ^dth each poison: 



\ pint molasses. 



1 or 2 ounces arsenate of lead, or zinc arsenite. 

 1 gallon water. 



A series of similar experiments were now performed with different 

 quantities of sodium arsenite, a soluble poison. One gram of sodium 

 arsenite dissolved in a gallon of water sweetened ^dth one-quarter of a 

 pint of molasses, killed the onion flies within a day; in fact, a few 

 specimens succumbed to the effects of the poison at the end of three 

 hours. Too much emphasis, however, should not be attributed to any 

 of these experiments, because the insects were in captivity and in feed- 

 ing were forced to consume the poisoned bait. 



In our field work, the first application of the spray was given to the 

 onion leaves to control the second brood of flies on July 10, 1913. The 

 poisoned bait was applied with a hand pump provided with a vermorel 

 nozzle. The minute droplets of the spray adhered to the waxy coating 

 of the onion leaves without a "sticker" being added to the poisoned 



