38 



CORN AND GRASS. 



infestation lies in autumn, or how it begins its attack on the young 

 Wheat, yet that we have got a strong ckie. 



The point which we liave wanted to make out throughout the years 

 of observation has been, is there ti suimiter brood / It appeared against 

 all likelihood, and contrary to all common insect habits, that the flies, 

 that came out in July or earlier, should remain alive and without egg- 

 laying until the time of the sprouting of the autumn or early winter- 

 sown Corn. Therefore we needed to ascertain whether there was a 

 second brood, of which the flies came out in autumn, in time to lay eggs 

 by the young Wheat. Failing these, there appears to be no possible 

 cause for this bad infestation, excepting the presence in the ground (in 

 autumn or winter) of eggs, or of maggots hatched from eggs, deposited 

 by the flies which we know come out about July. This, it appears to 

 me, from collation of observations, must be the case. We can put the 

 matter to practical proof presently, but meanwhile I think it will be 

 considered, from the following observations, that any other method of 

 infestation appears, so far as our information up to date goes, most 

 unlikely. 



First, about non-observation of second brood. In Mr. J. Eardley 

 Mason's notes (p. 36) we have the report of a pratised observer, and 

 one well acquainted with Wheat-bulb maggot attack, who, though 

 carefully watching the condition of Grasses for several years in a 

 Wheat-bulb fly infested district, yet never saw, amongst the various 

 forms of disease Avhich he noted, any instance of presence of this attack, 

 namely, that of the llijlcmijia coarctata. No one has ever reported it in 

 this country (or, as far as I am aware, any where else) as being found 

 in any part of the summer and autumn Wheat, or other Corn crops, 

 and therefore, if it is unknown both in Corn and common Grasses in 

 the summer (meaning by this the later part of the summer after the 

 first brood has come out of the ruined spring plant), this gives a very 

 strong presumption that a second or summer brood does not exist. 

 Therefore, that autumn attack is set on foot not hj flies laying their 

 eggs on the young sprouting Wheat, but by marjgots hatched from eggs 

 laid in the ground earlier in the year. 



This view is confirmed by the very peculiar customary limitation 

 of the area of attack to land which in the previous summer has been 

 under special conditions. It is very well known that where maggot 

 attack occurs it is usually after fallow, or on land that has been much 

 exposed to the sun. But besides the broad-scale observation of this, as 

 in whole fields, or fields of a whole district, it may be shown as 

 occurring almost to a line in portions of fields. We can point to small 

 attacked patches where ground was left bare by failure in a previous 

 crop ; again, we can point to a strip across a field being /r('e//o?» attack 

 where this part was protected by a crop which was ploughed late, 



