The protection of shorebirds need not be based solely on esthetic or sentimental grounds, for few groups of birds more thoroughly deserve protection from an economic standpoint. Shorebirds perform an important service by their inroads upon mosquitoes, some of which play so conspicuous a part in the dissemination of diseases. Thus, nine species are known to feed upon mosquitoes, and hundreds of the larvae or "wigglers" were found in several stomachs. Fifty-three per cent of the food of twenty-eight northern phalaropes from one locality consisted of mosquito larvae. The insects eaten include the salt-marsh mosquito (_Aedes sollicitans_), for the suppression of which the State of New Jersey has gone to great expense. The nine species of shorebirds known to eat mosquitoes are: Northern phalarope (_Lobipes lobatus_). Semipalmated sandpiper (_Ereunetes pusillus_). Wilson phalarope (_Steganopus tricolor_). Stilt sandpiper (_Micropalama himantopus_). Killdeer (_Oxyechus vociferus_). Pectoral sandpiper (_Pisobia maculata_). Semipalmated plover (_Aegialitis semipalmata_). Baird sandpiper (_Pisobia bairdi_). Least sandpiper (_Pisobia minutilla_). Cattle and other live stock also are seriously molested by mosquitoes as well as by another set of pests, the horse-flies. Adults and larvae of these flies have been found in the stomachs of the dowitcher, the pectoral sandpiper, the hudsonian godwit, and the killdeer. Two species of shorebirds, the killdeer and upland plover, still further befriend cattle by devouring the North American fever tick. Among other fly larvae consumed are those of the crane flies (leather-jackets) devoured by the following species: Northern phalarope (_Lobipes lobatus_). Pectoral sandpiper (_Pisobia maculata_). Wilson phalarope (_Steganopus tricolor_). Baird sandpiper (_Pisobia bairdi_). Woodcock (_Philohela minor_). Upland plover (_Bartramia longicauda_). Jacksnipe (_Gallinago delicata_). Killdeer (_Oxyechus vociferus_). Crane-fly larvae are frequently seriously destructive locally in grass and wheat fields. Among their numerous bird enemies, shorebirds rank high. Another group of insects of which the shorebirds are very fond is grasshoppers. Severe local infestations of grasshoppers, frequently involving the destruction of many acres of corn, cotton, and other crops, are by no means exceptional. Aughey found twenty-three species of shorebirds feeding on Rocky Mountain locusts in Nebraska, some of them consuming large numbers, as shown below. 9 killdeer stomachs contained an average of 28 locusts each. 11 semipalmated plover stomachs contained an average of 38 locusts each. 16 mountain plover stomachs contained an average of 45 locusts each. 11 jacksnipe stomachs contained an average of 37 locusts each. 22 upland plover stomachs contained an average of 36 locusts each. 10 long-billed curlew stomachs contained an average of 48 locusts each.