EXPERIMENT STATION REPORTS. 213 



and auother when the graijes are about the size of buck-shot and before 

 they touch in the clu.ster, it being possible at that time to make the spray 

 penetrate between the berries so that each berry receives a coat of poison 

 on all sides. 



I'aradichlorobenzene has apparently come to stay. Its use in tlie 

 control of the peach-borer has given us much gratification. Thus far no 

 harm seems to have resulted from its use in this way and the destruction 

 of the borers seems to have been almost complete. At any rate complete 

 enough to make it a commercial success. 



Our efforts toward getting the time for the most effective spray for the 

 second brood of the codling moth seem to have .been generally successful. 

 It would be of great value to run a string of cages straight across one or 

 two counties, from the lake shore inland in order to determine how far the 

 influence of Lake Michigan extends and just to what extent the time of 

 emergence and consequent hatching of the second brood of eggs is influ- 

 enced by the lake. This will be done next year if it is financially possible. 



For the first time in the experience of the writer, white ants actually 

 injured com in our State. An inquiry into the case revealed the fact 

 that there were in the field a quantity of decaying stumps which liar- 

 bored the termites and from Avhich they attacked the corn. 



The potato leaf hopper which causes hopper-burn in potatoes was prev- 

 alent during 1921 and is now appearing to a more limited extent in 1922. 

 We are recommending the use of Boixleaux. The addition of nicotine 

 sulphate adds to its effectiveness but the use of the latter poison seems 

 to be hardly warranted for use on potatoes owing to its cost, and in most 

 eases the grower seenns to be able to "get by" with the Bordeaux alone. 



For several years now the writer has been experimenting with a new 

 borer repellant directed primarily against the flat-head borer of apple. 

 Thus far the results have been yevj gratifying and if the results of the 

 present season do not prove contradictory we may hope to put out some 

 advice of commercial importance in the near future. 



Two new pests of fruit have appeared during the year, one tlie grape- 

 blossom midge, Contarinia jolinsoni, which destroys the grape while in 

 the bud stage and which has baffled groAvers in the East for several years ; 

 the other the apple flea weevil, Orrhestes canus, an insect apparently of 

 lesser importance which eats small pits in the foliage of apple. 



Another record of interest is the finding of a flea, hitherto found only 

 as a rarity in Brazil, a flea inhabiting the rat, and therefore, prop- 

 erly under suspicion as a possible carrier of disease. The few specimens 

 received came from Detroit and are known as Piilex hrazilensis. 



At no time in the past has the cockscomb gall of ebn, Colopha ulmicola 

 been so prevalent. Every day for months has brought in samples of this 

 aphis and of its work. Furthennore aphids of all isorts are plentiful. 

 The cool damp weeks of early spring being unfavorable to the develop- 

 ment of aphid parasites. Canning peas have suffered severely. The pea 

 •aphis, MacrosipJiwn pisi, developing on clover, early in the season and 

 migrating to the peas during July in swarms. Dusting experiments have 

 proven that it is possible to destroy the lice but whether this can be done 

 at a profit in the generality of cases is still open to grave doubt. The 

 development of a new killing agent for plant-lice, a cheaper killing agent 

 that can be used freely against plant-lice on potatoes, peas and many 

 other field crops, is still greatly to be desired. Nicotine is effective but 



