198 HOW TO GROW GOOD CORN. 



little doubt but that their periodical appearance, to 

 the extent to cause them to be recognised as blights, 

 is due to the thinning of their enemies ; and we have 

 always observed that a paucity of the Sirundines — 

 the swallow tribe of birds, their greatest enemies — is 

 coupled with a great increase of the smaller insects 

 which it is the vocation of swallows, bats, and others 

 of the hawking insectivorous creatures, to take on the 

 wing. 



3. The Wheat-midge {Cecidomyia tritici), also called 

 the Hessian-fly, is sometimes very destructive to the 

 wheat crop. In 1860 we observed the effects of this 

 creature to a greater extent than we have before 

 known, in not a few instances rendering the crop 

 scarcely worth reaping. Upon this creature we sent 

 the following notice to the Agricultural Gazette for 

 August 30, 1862 :— 



The wheat-midge {Cecidomyia tritici) has been so destructive for 

 the last two or three years, that every fact connected with its history 

 ought to be of great interest. Curtis tells us that "in Scotland one-third 

 of the crop was lost, and the farmers suffered severely in 1828 and the 

 three following years ;" whilst "in Suffolk the yield* of wheat was 

 one- third less in some districts in 1841 than was expected." 



The presence or absence of this insect is so important as affecting 

 the yield, that we now never fail to look for it in every crop upon 

 which we would offer a judgment in this respect. 



It is easily detected in the larva state on opening some of the chaff- 

 scales — pales — of affected crops, as in the interior of these will be 

 found some minute larvse (maggots) of a bright yellow or oi-ange colour. 

 In the earlier period of the blossom these larva? will be found about the 



* We believe this creature to be one of the most common causes of 

 deficient yield, so that a knowledge of its history is all-important in 

 estimating the value of a crop, which, as a rule, we should always put 

 lower in the seasons when this blight abounds. 



