103 



Research work has also been carried out on the pink bollworm of 

 €otton [Pectinophora gossypiella], sugar-cane insects in south-western 

 Texas, tobacco insects, and insect pests of castor beans. 



Forest insects were studied under the supervision of Dr. A. D. Hopkins, 

 and it was shown that the very heavy loss in ash logs in Mississippi 

 was due to failure to utilise them promptly after the trees were cut 

 and thus prevent the attack of borers. The California survey of the 

 pine belt along the western flank of the Sierra Nevada Mountains 

 showed that the loss in 1917 due to tree-killing beetles amounted to 

 about £12,000. In the south-west, where the mesquite [Prosopis] 

 furnishes the only local supply of fuel, etc., heavy losses occur each 

 year from wood-boring insects. It has been found that this can be 

 avoided by cutting in November and December and piling in loose 

 ricks. Timber cut during other months is seriously affected and in 

 some cases entirely destroyed. The black locust tree [Robinia 

 pseudacacia], which is valuable as supplying pins used in the construc- 

 tion of wooden ships, is so seriously damaged by the locust borer 

 [Cyllene robiniae] that hitherto it has not been found practicable to 

 grow it commercially. Experiments have shown, however, that 

 the young trees can be protected by spraying with a poisoned liquid, 

 or by the planting of some quick-growing shade-producing plant 

 between the rows in plantations. 



Investigations on the control of tropical and sub-tropical fruit insects, 

 under the charge of Mr. C. L. Marlatt, showed that the citrophilus 

 mealy-bug [Pseudococcus citrophilus], a comparatively new pest, 

 infesting a few trees in 1915 but now covering an area of about 1,000 

 acres, can be eliminated by spraying the trunks of the trees, utilising 

 predatory natural enemies, and controlling the Argentine ant 

 \Iridomynnex humilis] by the use of poisoned syrup. Investigations 

 on the use of hquefied hydrocyanic acid gas have shown that this 

 method bids fair to supersede that of generating the gas at the moment 

 of use. The control of the fluted scale [Icerya purchasi] has been 

 accomplished in and around New Orleans by the propagation and 

 liberation of over 300 colonies of Novius cardinalis over an area of 

 40 square miles, and also by the control of the Argentine ant. 

 Quarantine measures regulating the shipping of fruits and vegetables 

 from Hawaii to the mainland have been enforced as a means of protec- 

 tion against the Mediterranean fruit-fly [Ceratitis capitata] and 

 the melon fly [Dacus micurbitae]. 



The extension and demonstration work of the year is recorded in 

 detail, also the institution of a war emergency entomological intelligence 

 service. Bee-keeping extension work is fully treated, it having been 

 undertaken as a war-measure for increased food-production. 



During the year ended 30th June 1918 the area infested by the gipsy 

 moth [Porthetria dispar] in the New England States has increased by 

 1,880 square miles, nearly half of this being in Maine, an area in which 

 it is very difficult to prevent the spread of the small caterpillars owing 

 to the prevalent warm west and south-west winds. Isolated colonies 

 found during previous years appear to have been exterminated. 

 During the year the territory infested by the brown-tail moth [Nygmia 

 phaeorrhoea, Don.] has been reduced by 3,694 square miles. Special 

 attention has been paid in towns just within the border of the infested 

 areas to discovering and stamping out infestations on high elevations. 



