78 



OUK FARM CROPS. 



placed upon their ravages by a minute white parasite, the 

 Thrips minutissima, which feeds upon them. 



The "Corn Saw Fly" (Gephus pygmcvas) is a small fly, of 

 a shining black colour, not uncommon in our corn-fields, 

 and abounding on umbelliferous flowers, and the long 

 grasses that are met with in the hedgerows and waste 

 places, in June and July. The young maggot, of a 

 wrinkled yellow colour, with a dark head, is found inside 

 of the stem, which it consumes. About the time the ear 

 is formed, it has gradually increased in strength, sufficient 

 to enable it either to cut right through the node of the 

 stem, or, at all events, to cut so deep into it as to destroy 

 its vitality and its power to perfect the grain. The head 

 then rapidly assumes a ripened appearance, and readily 



separates from the stem at 

 the severed part. The mag- 

 got then descends the stem, 

 and incloses itself within 

 the knotted stump of the 

 straw, where it rests secure 

 through the winter, and in 

 the early spring changes to 

 a pupa, which, in due 

 course, is transformed into 

 the regular "saw-fly." Here, 

 again, we have to record 

 the presence of a friendly 

 insect, the small ichneumon 

 fly (Pachymerus calcitra- 

 tor\ which you will always 

 find busy at work, hunt- 

 ing after and destroying 

 our enemy the saw fly. 



There are numerous other insects found in our wheat 

 crops, with whose habits we are not so well acquainted, 



1. Female saw-fly, magnified ; 2, natural 

 size. 3. Maggot in the stem of plant ; 4 and 

 5, natural size and magnified. 6. Pachy- 

 merus calcitrator ; 7, natural size. 



