26 BULLETIN 134, L T . S. DEPARTMENT OF AGRICULTURE. 



Tomasi, of the Station Chimico-Agraria Sperimentale di Roma, 

 strongly recommended the prohibition of arsenicals for general 

 agricultural purposes. They conclude that their use is injurious to 

 all sorts of plants and animals, but the most potent of their reasons 

 is that the farmers, instead of poisoning their insect foes, might 

 destroy human life. In addition to these control measures practiced 

 in Spain and Italy, a small amount of spraying has been done around 

 Jaffa in Palestine for a species of thrips on the orange. From the 

 little evidence of thrips work that was seen at Jaffa the species occur- 

 ring there is not Euthrips citri, as was supposed. 



MEDITERRANEAN CITRUS FRUIT INSECTS THAT DO NOT OCCUR IN 

 THE UNITED STATES AND THE POSSIBILITY OF THEIR INTRO- 

 DUCTION. 



Of the citrus insects discussed in the foregoing pages, two do not 

 occur in the United States, namely, Ceratitis capitata and Prays citri. 

 Two others, Chrysomphalus dictyospermi and Parlatoria zizyphus, while 

 occurring in the United States, do not appear to be established as 

 important pests, as is the case in the Mediterranean region. Con- 

 cerning the distribution of these two scales, Mr. C. L. Marlatt, under 

 date of March 5, 1914, writes as follows: "■ 



Chrysomphalus dictyospermi is frequently found on palms and quite a number of 

 other plants which are probably imported, and has a wide distribution in greenhouses. 

 Out of doors it does not seem to thrive very well on this continent, and I think we 

 have very few outdoor records of it, and these naturally from southern points. It has 

 been so often brought into this country that its failure to establish a foothold in citrus 

 orchards apparently indicates unfavorable conditions for this insect, but it is, of course, 

 possible that this may have resulted, after all, from lack of favorable opportunity. 

 Parlatoria zizyphus, as you know, is brought to this country all the time on Italian 

 lemons, and has been found in the open market wherever these lemons are sold, in- 

 cluding well-established citrus districts such as those of Florida and Louisiana. 



In case these two scales did become established in our citrus groves 

 our present control methods, at least fumigation, would handle them 

 successfully. This fact, however, should be no exccuse for not quar- 

 antining against them. On the other hand, the other two, Ceratitis 

 capitata and Prays citri, would not only be serious pests but would 

 not be controlled by any of our methods now in use for citrus trees. 

 Ceratitis, moreover, is not limited as a pest to citrus fruits; indeed, 

 citrus fruits are by no means its favorite food, but it attacks a long 

 list of deciduous fruits. The scope of this paper has to do, however, 

 chiefly with citrus fruits. 



The first shipments of oranges are made from Spain as early as 

 October, and a few of the mature fruits at this time may contain 

 larvse of Ceratitis. But with the approach of cold weather in Novem- 

 ber and December the fly disappears. The time when infested fruits 

 might be received from Spain is at the beginning of the shipping sea- 



