BUREAU OF ENTOMOLOGY. 313 



but thus far only four species have been obtained. No fruit flies have 

 been bred from avocadoes, nor has any suspicious fruit been seen. 



Studies of greenhouse insects. — The strawberry rootworm. which 

 is a serious pest of roses under glass, has continued to receive a 

 large amount of attention, the Avork being done in cooperation with 

 the Pennsylvania State Department of Agriculture, Avith headquar- 

 ters at Doylestown, Pa. The life history of the pest has been fairly 

 Avell worked out and experiments in control have progressed to a 

 point to warrant the issuance of recommendations. Fumigation 

 with hydrocyanic-acid gas at the rate of 1^ to 2 ounces pev 1,000 

 cubic feet of space is not only suitable for a single unit type of house,, 

 but by using heavy muslin curtains the gas may be confined to any 

 section of an open-range house. A number of open-range houses, 

 involving 33.000 rose plants, have been fumigated consecutively at 

 the above rate with a mortality of beetles of about 97 per cent, and 

 no injury whatever to the plants Avas to be noted from the treatment. 

 It has also been ascertained that the rose beetle can be reduced to a 

 negligible quantity by keeping beds free from mulch, manure, and 

 dead leaves during the Avinter months if persistent hand picking of 

 the beetles is resorted to during the latter part of the summer. Fur- 

 ther studies of the bulb mite, Rhhoglyphus hj/aclnthi, have been 

 made, including tests of numerous insecticidal materials. Para- 

 dichlorobenzene proved to be most effective in killing the mites. 

 During: the fiscal vear studies of the greenhouse leaf-tyer have been 

 concluded and a control program worked out, involving a combina- 

 tion of remedies directed progressively against the several stages, 

 beginning with the adult. 



In cooperation with the superintendent of the United States Bo- 

 tanic Garden, important experiments have been carried out to 

 determine the practicability of frequent fumigation of greenhouses 

 Avith hydroc3'anic-acid gas in order to keep the greenhouses free from 

 such common insects as white flies, etc. No permanent injury fol- 

 lowed, and the houses were kept virtually free of pests by the 

 treatment given. The results are of much importance to florists 

 as indicating the desirability of adopting the practice of frequent 

 fumigation Avith reduced strengths of gas as a means of keeping 

 under subjection their injurious insect pests. 



The camphor scale. — Progress has been made in the iuA^estigation 

 and control of the camphor scale, Pseudaonidia duplex^ in coopera- 

 tion Avith the Louisiana State Department of Agriculture and the 

 administrative authorities of the city of New Orleans. The dis- 

 tribution of the insect was ascertained to be more general than anti- 

 cipated at first, demonstrating the impracticability of an eradication 

 program. Special attention was giA^en during the year, with funds 

 supplied largely by the State of Louisiana and the city of New 

 Orleans, to large-scale spraying operations to protect Aaluable shade 

 trees along the streets and in the parks. This work serA-ed as an 

 object lesson to many citizens in New Orleans, and. along with 

 other educational effort in progress, it is believed will serAC to in- 

 duce property owners to undertake spraying operations to protect the 

 trees on their own account. The camphor scale has also been found 

 at Hattiesburg, Miss., and quite recently at Grand Bay, Ala. These 

 outbreaks have been investigated and proper State authorities ad- 

 vised of the occurrence of the insect Avithin their States. Begin- 



