Show ALFALFA SEED PEST RESEMBLES THE GNAT 11 f 7 4 aw i 4 aa P Z alfalfa seed field with check ridges and fence lines burned over to destroy hibernating larvae of the fly prepared by the united states department of agriculture tho th alfalfa 1 falfa seed destroyer known as the fly does doea its destructive work lc in clover or alfalfa seeds from the gulf coast to the northern limits of the united states according to the united states department ot of agrical tures specialist who has baa personally seen seem the widespread devastation ol at this pest by harvesting severely infested crops by cleaning fence lines and ditch banks and by winter cult cultivation 1 the grower of alfalfa seea mav help to control this insect A new farmers Mul bulletin letin no entitled the chalala fly in alfalfa seed gives the details of these methods of control and mv be had bad tree free ot at charge on application to the department the chalala fly under the microscope is a formidable looking insect but when seen in the held field it is frequently confused cont used with the gnat these pests pesta may bo be seen been in great numbers flying over alfalfa seed shocks and swarming over the sickle bar when the alfalfa la Is being cut the eggs are so small as to be invisible to the naked eye and are deposited through the soft green seed pods poda directly into the soft seeds when the pods are about half grown immediately upon becoming a fly the insect eats its way out through the shells of the infested seeds then through the green pods large portions of the seeds are hollowed out in this manner when they are still green and growing the infected seeds which still contain the living larvae of at the insect may be recognized by their abnormal abnor maU shape and usually by the dull brown color some of the infested seeds however retain their natural color but they always lack the api ap 1 i bearance pe arance of norm normal al seeds the extent to which alfalfa seed is damaged by the ly fly to is not generally apparent owing to the minuteness of the insect and because becaas e its destructive work la is accomplished within tho the growing seeds the alfalfa seed grower can cami only estimate the percentage ot of his blis crop destroyed by opening a large the regular seed fields are sufficiently advanced for this cutting should bo be lone done with the harvesting of each hay bay crop before tho the seed crop la Is grown it la Is sometimes necessary to bava two or more irrigation ditches running parallel making it impracticable to cut the alfalfa between them in such cases it to Is economy to fence the ditches and use this land as a small summer pasture thus preventing the development of alfalfa seed pods and the chalcea flies winter cultivation in tho the process ot at harvesting tho the seed crop many pods containing infested seeds fall to the ground hero they remain until the following spring when the hiber hibernating hating insects emerge although cultivation with an alfalfa cultivator at some time late in tho the fall or in early winter will sufficiently cover such auch pods poda and will prevent the tha adov 7 k M alfalfa seed or clover seed fly A adult 0 larvae C pupi pupa much enlarged number ot the seed pods and observing the infested seeds harvesting infested crops an alfalfa held la is frequently found witt with such a severe infestation by chalees flies that the grower considers it of insufficient value to be Lar harvested vented and simply drives in a herd of cows to pasture the crop with regard to the control of the fly for the protection of future seed production this Is ia a costly mistake observations show that many of the pods burst open while others othera are trampled to the ground here great numbers of infested seeds offer favorable conditions tor for the hibernation of the chat cis dy larvae these as mature flies will infest the seed crops the following spring ander such circumstances the crop should be me mowed wed removed from the ilela and staked it way may then be used as rough fodder and it if the remaining straw is burned in early spring the hibernating larvae will be destroyed cleaning fence lines and ditch banks banka the following faals emphasize the import sace of cutting tho alfalfa astalfa along ditch banks and fence libes ches as aa well at ae in the fields 1 the earliest seed pods are found to develop on the isolated and vigorous growing plants found in such places 2 2 the barill earliest est pods have an especially daiy large percentage of oc the seeds infested with fly larvae i 3 the fly larvae are able to pass completely through the first I 1 generation in the earliest p do da before emergence of most of the adults when the tha warm weather arrives destroying the screenings after the alfalfa Is thrashed the great mass of screenings which is left frequently contains large numbers of seeds infested tn with hibernating larvae it if the chaff together with the screen ingo inga la is placed in a compost pile tor for three or four months so BO that it will become heated and decay moat ot of the insect life will be destroyed unless it to is possible to treat the screenings in III this manner they should bo burned before the growing season opens in III the spring many of the alfalfa seed pods along check ridges and fence euce lines may be destroyed by burning off the weeds and alfalfa this should be done either in the fall or early spring in III purchasing alfalfa seed farmers upon havinga teed seed has been well cleaned after thrashing and should never plant the ua cleared product in now new fields |