THE CHEESE SKIPPER AS A PEST IN CURED MEATS \) 



An advanced case of cheese skipper infestation in ham is shown in 

 Figure 1. The history of this infestation is given herewith to bring 

 out several points of interest, particularly the fact that large num- 

 bers of the insects may develop in one piece of meat. 



This dry-cured ham weighed 21 pounds and 4 ounces when removed 

 from the smoke on May 14, 1920. On August 15 it was found to be 

 infested, discarded as inedible, wrapped in paper, and placed in a 

 cotton sack. On May 10, 1921, after being stored during the winter 

 in a cold building, there were found to be 14,819 puparia, nearly all 

 empty, among the folds of the paper and on the surface of the meat. 

 Apparently none of the adults were able to escape, but large numbers 

 of dead ones were present. From May 13 until July 15, 1921, on 

 which latter date the ham ceased to produce skippers, probably 

 because of the presence of the predacious ham beetle Necrobia 

 rufipes, 37,808 full-grown larvae migrated from the interior of the 

 meat, making the total recorded production of skippers 52,G2T. On 

 October 31, 1921, this ham weighed 15 pounds, thus showing a loss in 

 weight, due to evaporation, the feeding of the skippers, and (toward 

 the end of the observations) to some feeding by ham beetles, of 

 6 pounds and 4 ounces in 18 months. The daily migration of mature 

 larvae from the ham is recorded in Table 1. 



Table 1. — Daily mi grat ion of larva? of Piophila casei from an infested ham from 

 Map 13 to July 15, 1921, at Washington, D. C. 



Date 



No. 



Date 



No. 



Date 



No. 



Date 



No. 



Date 



No. 



May 13 



75 



May 27 



308 



June 10 



648 



June 24 



988 



July 8... 



266 



14 



64 



28 



342 



11 



754 



25 



1,150 



9... 



254 



15 



152 



29 



333 



12 



758 



26 



920 



10- _ 



171 



16 



310 



30 



610 



13 



1,173 



27 



989 



11.. . 



97 



17 



417 



31 



799 



14 



1,265 



28 



887 



12... 



66 



18 



303 



June 1 



772 



15 



1,250 



29 



731 



13... 



28 



19 



280 



2 



813 



16 



1,230 



30 



667 



14.._ 



38 



20 



249 



3 



879 



17 



1, 226 



July 1„— 



591 



15... 



30 



21 



337 



4 



753 



18 



992 



2 



546 









22 



556 



5 



741 



19 



957 



3 



410 





37, 808 



23 



437 



6 



837 



20 



878 



4 



328 





1+14,819 



24 



763 



7 



721 



21 



949 



5 



340 









25 



444 



8 



689 



22 



990 



6 



332 



Total... 



52, 627 



26 



266 



9 



606 



23 



769 



7 



274 







Migrated before May 13. 



THE ADULT INSECT 



TECHNICAL DESCRIPTION 



Head black above, the front sericeous except for the large ocellar triangle, 

 toward the antennae narrowly yellow ; occiput finely roughened, polished, the 

 lower occipital orbits narrowly pruinose ; face, cheeks, mouth parts and 

 antennae yellow, the cheeks greatly broadened behind, vibrissa? prominent, oral 

 hairs weak or absent ; third joint of the antennae short, oval, the arista brown. 

 Notum black, with faint aenescent tinge, not smoothly polished but minutely 

 roughened, bearing three rows of fine setulae in lieu of the irregularly scattered 

 hairs of the other species of Piophila ; mesoplurae with scattered minute hairs, 

 proplurae pollinose. the bristle evident; scutellum convex. Abdomen more 

 oblong than usual, the black pubescence conspicuously long. Legs largely black 

 and hairy, coxae, trochanters, knees, and posterior tarsi more or less yellow. 

 Wings hyaline, veins pale, anterior crossvein shorter than usual but variable, 

 located beyond the middle of the widened discal cell, basal cells indefinitely 

 wider than usual, anal vein evanescent some distance, before the margin. 



Length 2.5 to 4 mm. 



6102°— 27 2 



