170 INDIRECT INJURIES CAUSED BY INSECTS. 



Mr. Markwick has given us the history of a fly that 

 attacks wheat in a later period of its growth, Avhich, if 

 it be not indeed the same, appears to be nearly related 

 to the Musca Pumilionis of Bierkander^, accused by 

 him of being extremely injurious to rye in the spring. 

 Our insect was discovered on the first sown wheats early 

 in that season, making its lodgement in the very heart 

 of the principal stem just above the root, which stem it 

 invariably destroyed, giving the crop at first a most un- 

 promising appearance, so that there seemed scarcely a 

 hope of any produce. But it proved in this and other 

 instances that year (1791) that the plant, instead of be- 

 ing injured, derived great benefit from this circum- 

 stance; for, the main stem perishing, the root (which 

 was not hurt) threw out fresh shoots on every side, so 

 as to yield a more abundant crop than in other fields 

 w here the insect had not been busy. These flies there- 

 fore seem to belong to our insect benefactors; and I 

 should not have introduced them here, had it not been 

 probable that in some instances later in the spring they 

 may attack the lateral shoots of the w heat, and so be 

 injurious. It is also not unlikely that the new progeny, 

 which is disclosed in May, may oviposit in barley or 

 some other spring corn, vi^hich would bring the next 

 generation out in time for the wheat sown in the au- 

 tumn. — These flies are amongst the last, and, in some 

 seasons, the most numerous, that take shelter in the 

 windows of our apartments when the first frosts indi- 

 cate the approach of winter, previous to their becoming 



" Jet. Stockh. 1778. 3. n. 11. and 4. n. 4. Marsliam in Limi. Trans. 

 ii. 79. This insect probably belongs to Latreille's genus Mosillas, and 

 seems related to Mosillus anualus, Gen. Crust. £^ Ins, iv. S57. 



