February 1942 y 
U. S. » E " 559 
\\ DEPARTMENT 
OF 
AGRICULTURE 
BUREAU OF 
ENTOMOLOGY AND 
rCANT QUAKANTIME 
MAY BEETLES, OR JUNE BUGS, ON PECAN IN LOUISIANA 
By W. C. Pierce, Division of Fruit Insect Investigations 1/ 
Introduction 
Fifteen species of May beetles, or "June bugs" (Phy llophaga spp.), 
have been observed attacking the foliage of pecan trees in Louisiana. These 
beetles have been sufficiently abundant at periodic intervals completely 
to defoliate large numbers of pecan trees in the northern and western por- 
tions of the State. The damage has been more extensive on pecans growing 
in upland soils, but young pecan trees growing in river bottoms have also 
suffered severe injury. 
Observations of injury on pecan in Louisiana by Howard Baker and 
the writer from 1929 through 1937 have indicated that May beetles are 
abundant at 2-year intervals. During this period the beetles were most 
abundant in 1929, 1931, 1933, 1935, and 1937. 
Nature of Injury 
May beetles feed on and cut off opening buds, shoots, leaves, and 
flowers of pecan trees during the early part of the growing season, before 
the young nuts have formed. Trees completely defoliated by beetle feeding 
make very little growth during the first 2 months of the growing season, 
make poor or ragged growth thereafter, and produce no nuts. 
1/ The writer expresses his appreciate on'of the" help and interest~6f 
C. r. Nickels, in charge of the Brottriwood, Tex., laboratory of the Bureau, 
under whose general direction this work was performed. Grateful acknowledg- 
ment is also made to E. A. Chapin. Curator of Insects of the U. S. National 
Museum, for identifications of the adult beetles, to A. G. Boving. of the 
Bureau of Entomology and Plant Quarantine, for identifications of the 
immature forms of Phyllophaga, and to B. G. Sitton, of the Bureau of Plant 
Industry, at Shreveport, La., who aided in securing photographs of May 
beetle injury to pecan trees. 
