PEGOMYA FUSCICEPS ZETT.)L

February, '16] SCHOENE: SEED-CORN MAGGOT 131 THE ECONOMIC STATUS OF THE SEED-CORN MAGGOT (PEGOMYA FUSCICEPS ZETT.)l By W. J. SeRoE"'"'];, Blacksburg, Va. This insect is known as the seed-corn maggot, though it is said to injure sprouting beans and peas, seed potatoes, and the roots of cabbages and onions. The early history of the species has been fully tr,eated by Slingerland,2 Chittenden 3 and others. P. fuseieeps attracted much attention during our study of the cabbage maggot Downloaded from and at times it was difficult to tell from collections of adults which was the ~nore Important species. There have been some specimens of fuseieeps in practically all our collections of adults of P. brassieCE, the numbers varying with the season and the location where the flies were captured. In one experiment in which the adults of brassiere http://jee.oxfordjournals.org/ were collected as they emerged from a badly injured cabbage seed-bed4 the males of this species constituted 23 per cent of the total number of males. In sweepings of pea-fields or wild mustard, males of fusciceps were frequently more numerous than those of the associated species. Because of the uncertainty of the part played by this insect, some efforts were made to ascertain its habits and to find its other hosts. To that end many large fields of peas, beans and potatoes in Ontario county, New York, were examined for injured plants. However, by guest on April 13, 2016 very few infested plants were found and for a period of eight years only a few cases of injury were ever reported from that region, though peas, beans and potatoes are among the principal crops. In spite of our efforts, the importance of the insect was a matter of some doubt until the following observations were made. During the autumn of HIll a number of examinations of the crop remnants of!1 cabbage field were made to secure material for breeding experiments. The field in question contained a large number of sprouted cabbage heads; that is, heads that had ripened and then because of abundant moisture had put forth new growth. These heads contained terminal sprouts eight to fifteen inches high. After the head is broken it is no longer marketable, so these had been left in the field after the crop was harvested and many of them had become infested with maggots. Apparently the eggs had been deposited 1 Contribution from the Department of Entomology of the New York State Exper- iment Station, Geneva, N. Y. 2 Cornell Agr. Exp. Sta. Bul. 78, p. 499. aU. 8. D. A. Ent. Bul. 33, p. 84. f Jour. Eco. Ent, 4: 210. 132 JOl:RXAL OF ECO","O:\IIC EXTO:llOLOGY [Vol. 9 at the point where the sprout had broken through the head. These sprouted cabbages were in various stages of decay. Some of the decayed parts of such plants contained a number of fllsciceps larvre, while heads that were not decayed contained no fusciceps larvre, although more or less infested with larvre of brassiccr. These conditions suggested that the laceration of the plants by the larvre of brassicce and the development of areas of decaying tissue had made the heads attractive to fusciceps. In all our examinations of material in which brassicw larvre were breeding there has been every indication that this species prefers sound tissue. This fact, when considered in connec- tion with the well-known range of food materials of this species, has led us to believe strongly that at least in this instance fllsciceps was Downloaded from largely a secondary pest of the cabbage, attacking the plants only after rotten tissues developed. However, in going over some of the accounts of the work of P. fusciceps it is evident that some entomologists have believed the insect http://jee.oxfordjournals.org/ to be capable of causing injuries to growing crops. Chittenden l states that" the seed-corn maggot was observed during April and May doing great damage to late planted beans in the vicinity of Diamond Springs, Va. In certain areas rows were entirely killed off, necessi- tating replanting." Also, "during the spring of 19.09extensive injury to seed potatoes was incurred in Tidewater, Virginia." Although P. fusciceps has been reported as injurious many times there are a few writers who have suggested that cool, wet weather has by guest on April 13, 2016 something to do with the appearance of the insect in sprouting seed. Fletcher2 says, "Corn sown during a cold, wet period by which germi- nation is unduly delayed is very liable to be attacked by the corn-seed maggot." During 1910 the farmers in certain sections of the central west became much alarmed because large areas planted to corn failed to germinate and upon examination found the seed to be infested with small worms. Regarding the outbreak, Dr. Forbes 3 makes the following statement: "The insect injury is due to two insects, called respec- tively, the black-headed grass maggot and the seed-corn maggot, both of which are particularly liable to infest seed corn which has been in the ground a long time, either dead and decaying, or softened and possibly sprouting, but delayed in growing. Injuries by these insects are at present, I think, not so serious as they seem, thc main damage being done by the weath~r." In conclusion, there are positive indications that the insect does occasionaly feed upon partially decayed matter, but we have no 1 Va. Truck Exp. Sta. (Norfolk) Bu\. 2, p. 34. 2 Central Exp. Farms Ottawa Bul. 52, p. 35-36. 30mO Farmer, p. 702, 1910. February, '16] E~TO~IOLOGISTS'DISCUSSIO~S 133 evidence to show that it will not also feed upon healthy plant or animal tissue. It is believed that if entomologists would study the conditions favoring the development of large numbers of P. f1lsciceps, its economic status would soon be determined. ]\tIR. J. M. ALDRICH: Recently in Michigan I had a conversation with Professor Pettit, and he told me that this fly is very injurious to beans in that state, destroying the young plants. I also heard the same complaint about its habits in Canada, when I was lately at Ottawa. It seems to be very important. MR. T. H. PARKS: In regard to the injury this insect does to beans, Downloaded from I wish to add a little to what Dr. Aldrich has said. In southern Idaho during the spring of 1914 Pegomyia fusciceps appeared in wholesale numbers in bean fields, the maggots attacking the sprouting beans after the young plants had developed the second leaf. Inasmuch as the young plants were soon killed, there was certainly circumstantial http://jee.oxfordjournals.org/ evidence that the maggots were attacking the living plant beneath the surface, and also the sprouting seed. The 'injury extended over several large areas ranging in altitude from 2,800 to 4,500 feet, and in some cases the crop was entirely destroyed. They were also seriously injuring potatoes and in some cases where potatoes followed a wheat crop of the previous year. I reared P. fusciceps from maggots found in the "bulbs" of young wheat plants in Kansas in 1909, and can add this host plant to the by guest on April 13, 2016 list presented by Mr. Schoene. It is doubtful if wheat constitutes a favorable host plant for this insect, although in Idaho I have noticed serious infestation to potatoes where this crop followed wheat. ~IR. N. F. HOWARD: This species formed a considerable per cent of 10,000 adults of the three species (brassic{£, fusciceps, cepetorum) caught at Greenbay, Wis., last summer. It was also found hibernating in the pupal stage in onions, and was bred from both cabbage and omon. MR. GEORGEA. DEAN: In Kansas, I found in two or three cases that corn was badly infested where it followed wheat. I do not know whether the maggots infested the wheat planted the previous year, but I did find that it was much worse in the two or three corn fields which followed wheat. PRESIDENTGLENN W. HERRICK: We will now hear the paper by Mr. J. G. Sanders. RECORDS OF LACHNOSTERNA IN WISCONSIN By J. G. SAKDERS, Madison, Wis. (Withdrawn for publication' elsewhere).

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