INSECT CONTROL 297 



of Hippodamia convergens (a species of ladybird) boxed 

 in 60,000 lots each, in screened cases, and in our own cold 

 storage. We handle them in large cages, run them into a 

 chute, and handle them like grain. They are for the melon 

 growers of the Imperial Valley." 



The final, and most important, stage in this work is the 

 transfer of beneficial insects from one country to another, 

 and, though his efforts were unsuccessful, the credit for 

 priority belongs to Dr Asa Fitch, an American entomo- 

 logist. Sometime in the early eighties the European wheat 

 midge, Contarinia tritici, had been introduced into America, 

 and in 1854 a most disastrous attack by this insect dev- 

 astated the wheat crops of the Eastern United States. Dr 

 Fitch knew that in Europe the midge was heavily parasit- 

 ised and that, accordingly, it did relatively little damage. 

 Speculating as to the cause for the dissimilarity of the 

 status of the pest in the two countries, he wrote : " There 

 must be a cause for this remarkable difference. What can 

 that cause be ? I can impute it to only one thing we here 

 are destitute of nature's appointed means for repressing 

 and subduing this insect. Those other insects which have 

 been created for the purpose of quelling this species and 

 keeping it restrained within its appropriate sphere have 

 never yet reached our shores. We have received the evil 

 without the remedy, and thus the midge is able to multiply 

 and flourish, to revel and riot, year after year, without let 

 or hindrance. This certainly would seem to be the prin- 

 cipal if not the sole cause why the career of this insect 

 here is so very different from what it is in the Old World." 

 Requests by Dr Fitch to British entomologists to study 

 the matter and send parasites to America came to naught. 

 In 1873 an American predatory mite, Tyroglyphus phyl- 

 loxera?, which in its own country feeds on the vine phyl- 

 loxera, that scourge of European vineyards, was imported 

 into France, without appreciably checking the pest. 



The transportation of parasitic and predatory insects 



