i8o LETTERS TO PROFESSOR RILEY [CHAP. xvm. 



considered them to be Ephestia of a species previously 

 undescribed, and they were named by him kuhniella (fig-4i) 

 specifically after their observer. All this most likely you 

 know well, but it is the appearance of this "pest" here 

 which I am more particularly writing to you about. In 

 1887 the caterpillars did great harm in some large stores in 

 London, and last year the attack established itself in a 

 wheat-flour steam-mill in the North of England. The 

 great harm caused is by reason of the caterpillars " felting " 

 up the meal or flour by the quantity of web which they 

 spin in it. They feed, of course, but this is not so injurious 

 as working up the flour together, as thus they clog the mill 

 apparatus to a very serious extent. I have much reduced 

 their numbers by getting the manager of the steam-mill to 

 turn on steam to scald them; and cleaning, whitewashing, and 

 some use of paraffin have done good. The real cure would 

 be to change the material ground. If we could use rye- 



2 



3 



i, Moth, with wings expanded ; 2, moth, at rest ; 3, caterpillar ; 

 4, chrysalis all magnified ; lines showing natural length. 



FIG. 41. MEDITERRANEAN FLOUR MOTH, EPHESTIA KUHNIELLA, ZELL. 



meal for a few weeks we could clear out effectually this 

 wheat-flour-feeding caterpillar. Unfortunately, however, the 

 delicate apparatus of our recently arranged wheat " roller " 

 mills does not allow of this. One point that would help us 

 in preventive measures would be to know where the attack 

 comes from. I am told it is a " scourge " amongst the flour 

 (or rather the meal, as it prefers the more branny parts) in 

 wheat from Russia and Hungary at the Mediterranean ports, 

 so I am making inquiries ; but Dr. Lindeman is not aware 

 of this attack having been noticed in Russia. Under these 

 circumstances I thought that I would write to you about it, 

 and if you are acquainted with this moth and the larval 



