304 



Insects Injurious to Wheat. 



Vol. XI. 



north-eastern part of Pennsylvania, probably 

 twelve or fifteen hundred feet above the 

 level of the ocean, in the summer of 1835, 

 after one of the severest winters for twenty 

 years, the only two peach trees observed in 

 travelling many miles, were full of peaches; 

 while the same winter, in Stroudsburg val- 

 ley, a large tree was noticed killed down to 

 the ground. While those hills are often 

 covered with snow throughout the winter, 

 the valleys are subjected to thaws, and 

 hence become more unfavourable to tender 

 vegetation. 



Most of these cases show the great advan- 

 tages of elevated sites. A dry and firm soil 

 is, however, quite important. The influence 

 of a compact knoll, rising scarcely above 

 the rest of the field, has saved the corn 

 which grew upon it; while on the more 

 mucky and spongy portions of the rest of 

 the field, radiating heat more freely, the 

 crop has been destroyed. A successful cul- 

 tivator of drained swamps, told me he could 

 never plant such lands with corn safely till 

 two or three weeks after the usual time oi 

 planting in common soils on an equal level. 

 These influences apply with greater force to 

 tender trees. Succulence and lateness of 

 growth, caused by such soils, are always un- 

 favourable to the endurance of cold ; while 

 a hard, dry soil, at the same time that it 

 produces a less rapid growth, causes also an 

 earlier cessation, and the young wood be- 

 comes matured and hardened before severe 

 frosts. "Many kinds of herbaceous plants 

 and small shrubs," says A. J. Downing, 

 ♦• may be naturalized on dry rock-work, or 

 aggregations of stones mingled with soil, 

 where they are found to thrive perfectly, 

 We observed in the Botanic Garden at Cam^ 

 bridge, an Azalea indica and a species of 

 Erica, that had braved the exceedingly low 

 temperature of 30 degrees below zero, the 

 past winter, having been planted several 

 years previously in a mass of rock work, 

 where they had annually matured their 

 wood in the most perfect manner." The 

 successful cultivation of the peach and 

 grape, on the gently swelling hills called 

 mounds, in the western prairies, while the 

 crops are destroyed by frost on other lands, 

 more fertile, affords another example. In 

 Lycoming county, Pa,, on the banks of the 

 Loyalsock, a creek so rapid that no muck is 

 deposited, but fine dry soil, peaches have 

 been raised, though the cold is often intense. 

 It will be observed that in the preceding 

 remarks, the influence of large bodies of 

 unfreezing water, in softening the severity 

 of the cold, in chilling the dangerous warm 

 air which starts the buds in winter, and 

 which afford great protection by the screen 



of fog which they spread before the morn- 

 ing sun, has not been taken into account 

 This influence, where it exists, will in some 

 cases, reverse some of the preceding rulea. 

 J. J, Thomas. 



Macedon, Third mo., 1847. 



From the Maine Farmer. 

 Insects Injurious to Wheat. 



Sir, — Being very desirous of obtaining 

 the means for completing the history of 

 some of the insects injurious to grain, and 

 having seen several articles on this subject 

 in the "New England Farmer," copied from 

 the "Maine Farmer," I have taken the lib- 

 erty of addressing you respecting them. 



There are several different kinds of in- 

 sects which are injurious to wheat ; and ag- 

 ricultural writers are not commonly enough 

 acquainted with natural history to distin- 

 guish and describe the kinds correctly. This 

 is the source of the contradictory statements 

 and unsatisfactory discussions that have ap- 

 peared in the public prints respecting the 

 history and ravages of these insects. 



One of these insects is the Hessian fly, 

 the grub of which confines its attacks to the 

 stems of the wheat, near the ground. 



Another is the wheat fly — Cecidomyia 

 Tritici — which, in its first or young state, 

 is an orange coloured maggot, without legs, 

 and growing to the length of one-tenth of 

 an inch only, and never suspending itself by 

 a thread. It lives in the ears of the wheat. 



A third is a " worm" — probably a kind of 

 caterpillar — color variously described, grow- 

 ing to the length of one quarter of an inch, 

 or more. It is found on the ears of the 

 wheat, and it devours the substance of the 

 grain. I have now some grains of wheat 

 more than half eaten by an insect, said to 

 be of this kind. This " worm," as it is gen- 

 erally called, has been compared to the 

 " clover-worms," which are sometimes seen 

 suspended by threads from the clover in the 

 mow, and it has the same power of spinning 

 threads and of suspending itself thereby. 

 Permit me to refer you to my work on in- 

 sects injurious to vegetation, pages 445 to 

 447, where has been collected a summary of 

 the various accounts respecting this particu- 

 lar kind of wheat insect. It is possible that 

 these accounts refer to more than one kind; 

 but it is certain that they cannot, if correct, 

 refer to the orange colored maggot of the 

 wheat fly above mentioned. The great dis- 

 parity in the size is sufficient to show tiiat 

 the insects are not the same ; and the habit 

 of suspending itself by a thread, peculiar to 

 caterpillars, is not found in the true maggots 

 of the Cecidomyia or wheat fly. 



