272 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
GENERAL HABITS OF THE CHRYSOMELIDAE 
As the common name imphes, nearly all the members of this family 
as adults or larvae, or both, feed on the leaves of plants. The adults 
of all North American species are diurnal feeders. They usually move 
rather slowly over the surface of the leaves. Most of the flea bene 
however, have stout hind femora and can leap some distance when 
disturbed. The species that are free living in the larval stage are 
gregarious in their feeding habits, and it is a common thing to find 
the adults and larvae of two or more instars on a leaf at the same time. 
The eggs are generally yellowish and are, as a rule, laid in groups or 
clusters on the lower surface of a leaf or on the stem of the host plant 
and secured by a mucilaginous secretion. The eggs of the leaf-mining 
species may be laid on the leaf or thrust into punctures made by the 
female. 
A few species are leaf miners in the larval stage, and most of 
these are solitary feeders. When two or more mines are in one leaf 
the larvae generally feed apart, but if the mines join usually only 
one larva completes development. The few casebearing species men- 
tioned are not important as foliage feeders in the larval stage. 
When ready to pupate, many of the free-livi ing larvae of the Chryso- 
melidae fasten themselves to the surface of a leaf by the last abdominal 
segment. Others pupate in the ground. Many of the leaf miners 
pupate within the leaf where they developed, but some bore out of the 
leaf into the ground. The casebearers transform within their sealed 
cases. 
The feeding pattern of the adults is characterized by holes cut 
through the leaf or a skeletonization, generally of the lower surface. 
The free- lhving larvae remove the epidermal layers on the upper or 
lower surfaces of the leaf, or both, whereas the leaf- -mining larvae 
devour the tissues between these epidermal layers. Some species 
restrict their activities to certain tissue layers of the leaf. Heavy 
feeding, by either of these larval forms, causes a distinctly brown or 
burned appearance of the trees attacked. 
According to Leng (273) and Leng and Mutchler (274, 275), about 
1,250 species of this family are known to occur in North America north 
of Mexico, many of which (as the Colorado potato beetle, the asparagus 
beetles, and the cucumber beetles) are of great importance to agri- 
culture. Only a few of the species are serious forest or shade tree 
pests, and the most important of these are of European origin. They 
attack mainly broadleaved trees, although a few feed on conifers. All 
of them can be controlled by a stomach poison (p. 52). In leaf miner 
infestations, spraying should be done at the time the leaves are de- 
veloping, in order to kill both the adults and the larvae before the 
latter bore into leaves. For species whose larvae feed externally, the 
spray operation should be carried out when the larvae are first noticed, 
and care should be taken to cover the under surface, as well as the 
upper surface, of the leaves. If there is a second generation the same 
procedure should be followed. 
