172 



natural enemies of the borer have been imported from Europe, and 

 about 6,000 parasites of two or more species have been liberated in 

 eastern New England. 



Owing to the very serious outbreaks of grasshoppers in North 

 Dakota and the surrounding States during the past three years, a 

 sum of about £8,000 was appropriated for work against them. At the 

 time of writing these outbreaks showed definite signs of abatement. 



Great success attended the use of poisoned bran baits against 



crane-fly larvae [Tipula simplex and T. qualei] destroying the grass 



on cattle ranges in the interior valleys of Cahfomia. It was found 



that from 70 to 90 per cent, of the larvae could be destroyed at a cost 



of about 2s. per acre [R. A.E., A, ix, 575]. The general incidence of 



Hessian fly [Mayetiola destructor] did not increase in intensity, and in 



the winter- wheat belt co-operative work resulted in a material reduction 



of losses. Chinch bugs [Blissiis leticopterus] continued to be serious 



in Missouri, Illinois, Indiana, and parts of Ohio. In addition to the 



successful method of spraying against the alfalfa weevil [Hypera 



variabilis] mentioned in the previous report [R.A.E., A, ix, 111], 



the further introduction from South Europe of natural enemies of 



this pest was decided upon. One species, imported before the war, 



is doing effective work in some localities. For the first time in several 



years an outbreak of green bug [Toxoptera graminum] occurred in 



the spring, being favoured by the mild winter, during which it was 



abundant in Northern Texas. As the season advanced, it appeared 



in Oklahoma, Kansas and Missouri, and might have become disastrous 



but for the advent of dry, warm weather in March and April, which 



allowed parasites to increase and check the pest, so that, although 



the oat crop in Northern Texas was seriously injured, the damage 



to winter wheat was comparatively shght. Self-sown oats and wheat 



should be destroyed instead of encouraged as at present, because these 



provide continuous shelter and breeding places. As sunflowers are 



being adopted for silage in certain parts of the West, an investigation 



of the insects affecting them has been begun. The wheat midge 



[Contarinia tritici], after doing httle harm for 50 years, has become 



progressively injurious during the past two years in Washington and 



Oregon. With the introduction of the hairy vetch as a forage and 



seed crop in the Carolinas the corn earworm [Heliothis ohsoleta] has 



attacked it severely [R.A.E., A, ix, 577]. 



The beneficial results of expert advice relating to insects attacking 

 stored maize and other grain products has paid many times the cost of 

 the research connected with the problem. The control of pea and bean 

 weevils by cold storage and fumigation has been studied. Fumigation 

 has been shown to give complete protection to peanuts in the shuck, 

 so that stocks can be kept indefinitely. Fumigation also largely pre- 

 vents the damage to baled skins by the hide beetle [Dermestes], 

 amounting to an annual loss of about ^200; 000 Meat of the same 

 value has been condemned as a result of insect infestation, and experi- 

 mental control work has been begun. 



The Japanese beetle [Popillia japonica] is now known to occupy 

 80 square miles in New Jersey and 10 in Pennsylvania. The barrier 

 policy [R.A.E., A, ix, 111] has been discontinued. It is hoped that 

 some peculiarity in the habits of this beetle will be found that will 

 enable its numbers to be reduced. Several shipments of predatory 

 and parasitic insects have been made from Japan, and the native 

 enemies of white grubs in other parts of the United States and certain 



