124 



AGRICULTURAL . REPORT. 



be necessary to commence with a short description of their trans- 

 formations, natural history, and habits, so as to show at what period of 

 their existence it is they do the most injury, and to enable us to decide 

 as to whether it is in the egg, larva, pupa, or perfect state that the 

 insect can the most readily be found and destroyed. 



The order of Diptera includes such insects, or flies, as possess two 

 wings only, and are provided with a i)roboscis or trunk for sucking 

 alone, and not with mandibles, or jaws, for biting or masticating their 

 food. This order is very important to farmers, as producing several of 

 the most minute, but at the same time most formidable enemies which 

 they have, as, from the extremely small size of the larvce, and their 

 habit of hiding or burrowing in the stems, leaves, or roots of plants, 

 they escaiie observation until the injury has been accomplished. 



The immense numbers, also, in which the flies appear all at once, en- 

 able them to spread almost simultaneously over his fields and lay their 

 eggs in or on nearly every individual plant in it, before anything can be 

 done to prevent them. The egg of the female fly being deposited in 

 some suitable locality, in the course of a short time a larva or maggot 

 is hatched from it, which is generally of a yellowish dirty- white, or 

 greenish-gray color, with a soft, naked body, and having no legs. 

 Some of these larvtB are provided with a distinct head, but many of 

 them have no apparent head whatever, and that part is merely indi- 

 cated by its position at the anterior part of the body. It is worthy of 

 observation, also, that it is in this larva state that the Biptera do the 

 most injury to vegetable products, by eating or boring into roots and 

 stems, mining into leaves, seeds, and fruits, forming galls, &c. The 

 larvce of the grain-destroying Biptera are generally so minute, and hid- 

 den within the substances they attack, that they escape the observation 

 of the farmer until the damage is done, and it is only by the sickly yel- 

 low appearance of his crop 'that the agriculturist is led to examine the 

 plants in order to find out what is troubling him, and then, too late, he 

 discovers the millions of almost invisible grubs which have totally 

 ruined his hopes of a good harvest. When the larva of a dipterous 

 insect is fully fed and ready to undergo its metamorphosis, it either sheds 

 its skin and changes into a naked pupa, or, the skin of the larva shrink- 

 ing and hardening, it assumes an oval form, and changes to a chestnut 

 or brown color, and it is in this hardened skin of the former larva that 

 the pupa is formed, which lies, for a shoii;er or longer period of time, 

 perfectly motionless, and eats nothing whatever, until at last the per- 

 fect fly bursts out of one end of its pseudo cocoon, and flies off to per- 

 petuate its species on the surrounding plants. 



It is in the perfect or winged state only that many of the Biptera 

 annoy mankind and cattle, by inercing the skin in order to suck the 

 Fig. 9. blood, as in the case of the horse or 



gad flies, the mosquito, and many 

 \ ^^^ ^^ *\e j>^ others. In some of the other D?*2?<em, 



however, the pupa is not quiescent, 



but is active and lively, as in the case 

 j, .1 / if ^ 1 V ^^ *^® mosquito, the pupa of which 



I V y/ 111 ^v insect swims about in the water with 

 \ ^ ^ \ great activity and restlessness. 



The larva of the common mosquito 



(Fig. 9) lives in stagnant water, and 

 may be seen on any summer day swimming about, with a sort of wrig- 

 gling motion, in small ponds or pools of water by the roadside, and 

 especially, in rain-water reservoirs or hogsheads placed under the spouts 



