INSECT ENEMIES OF EASTERN FORESTS 173 
in small quantities, but, on the basis of present information, they 
cannot be said to be destructive to nurseries and plantations. Larvae 
have been collected in both pine, especially jack pine, and hardwood 
stands. The heaviest concentration so far discovered was in a heavy 
stand of nearly mature aspen-white birch on the Huron National 
Forest. The species probably overwinters in both the adult and larval 
stages. The life cycle is 2 or 3 years, and the adults are most common 
in June and July. 
The genus )iplotaxis Kby. is another one of the little-known groups, 
as yet without a recognized common name. The adults are more 
oval-shaped than those of Dichelonyx, and are light brown to blackish. 
The exoskeleton is exceedingly hard and rigid. All species seem to 
be nocturnal, and most of them feed on conifers, the pines being the 
preferred food. 
In the jack pine and red pine stands in the Lake States, Diplotaxis 
sordida (Say), a slate-colored beetle having the pronotum covered 
with yellowish hairs, and DP. liberta (Germ.), a smooth, blackish spe- 
cles, appear to be the most abundant. VL). hayden? Lec. has been taken 
on the Hiawatha National Forest, and undoubtedly occurs in other 
northern areas. ‘This is a large, shiny beetle, much hghter in color 
than the two forms named above. Various other species are known in 
the Eastern States. 
Diplotaxis larvae, under experimental conditions, fed on the roots 
of coniferous seedlings. ‘They cannot, however, be said to be destruc- 
tive to nurseries and plantations except, perhaps, where extremely 
heavy concentrations occur. Under such conditions they destroyed 
less than 20 percent of the 1—0 and 2-0 pine seedlings used in connection 
with the experiments. It is believed that this degree of injury would 
seldom or never occur in the field. 
The group has a 2- or 3-year life cycle. Adults are most abundant 
in June and July, at which times hundreds of )iplotaxis liberta have 
been collected at light traps in a single night. LY. sordida does not 
seem to be particularly attracted by lights. Larvae, as far as known, 
have never been collected far from pine trees, and the genus, in the 
Lake States, apparently is not associated with pure hardwoods. The 
heaviest grub concentrations were collected in the immediate vicinity 
of open, mature jack pine. 
The long-legged, tan beetles of the genus J/acrodactylus Latr. are 
about 10 mm. long and are well-known pests of rose and flower gardens. 
They are appropriately called rose chafers. During the mating 
season, in gardens and some forested areas, they may literally cover 
certain flowering plants. Adults appear in June in the more northern 
localities. The initial emergence is sudden and swarmlike, soon after 
which the beetles gather on the nearest flowering plants. In the Lake 
State forests these are New Jersey tea, the numerous species of roses, 
and various flowering herbs. The beetles are actively mating during 
the first few days, following which the adults scatter to black oak 
and other hardwood species and soon die. The rose chafers have a 
1-year life cycle, and overwinter in the larval stage. In the Lake 
States, oviposition seems to be heaviest around clumps of New Jersey 
tea, as indicated by larval concentration near these plants. 
The chief species is the rose chafer (Macrodactylus subspinosus 
(F.)), but a few other forms are known. Rose chafer larvae are 
