INSECT ENEMIES OF EASTERN FORESTS hd ks? 
The antennae of the land forms are usually rather long, the pro- 
thorax is large and free, and the mesothorax and metathorax are fused 
together. All species in this group that attack forest and shade trees 
are winged in the adult stage, with the forewings, or elytra, thickened 
for about the basal one-half and the distal ends membranous (except 
in the Tingidae, where the elytra are membranous over the entire sur- 
face). The wings li flat over the back when folded, and the mem- 
branous tips overlap. 
In the Heteroptera the mouth parts usually are located near the 
front of the head. The mandibles and maxillae, drawn out to form 
piercing stylets, are adapted for sucking. The maxillae lie with the 
two inner faces pressed together, and the inner surfaces are grooved, 
forming tubes. The mandibles form a sheath around the mavxillae, 
which strengthens and holds them in place. 
The feeding habits of this group vary greatly, even within a species. 
Some species are entirely phytophagous, some feed now and then on 
either plants or insects, some are phytophagous in the early instars 
and predaceous later, and others are entirely predaceous. 
In their feeding on plant growth these insects may produce injury 
of various types. Secretions of the salivary glands, injected into the 
plant while the insects are feeding, may prove to be more harmful 
than is the withdrawal of plant juices. The toxic effect of these secre- 
tions often causes the plant tissue around feeding punctures to turn 
brown, to become distorted, and eventually to die. Large numbers of 
such punctures may even kill entire plants. Feeding by insects in this 
group may also cause a stoppage in the conductive tissues of plants, 
and a comparatively few insects may kill a twig or branch, and heavy 
infestations may killa tree. In their feeding on plants, these insects 
may also transmit diseases, although known instances of such trans- 
mission are uncommon. 
The biology of many species of Heteroptera remains undetermined. 
The number of generations each year varies widely among species, and 
within any species, according to the length of the season and the alti- 
tude and latitude. The winter may be passed in either the adult 
or the egg stage. All species undergo gradual metamorphosis, in 
which newly hatched nymphs, as well as those in successive stages or 
instars, bear a striking resemblance to the mature insects. In the 
immature stages color changes may develop from molt to molt, and 
fully developed wings are not present until the adult emerges. In 
some pentatomids the first-instar nymphs do not feed, but all other 
stages feed during their development. mn 
Eggs of the different groups vary greatly in appearance. ‘Those of 
the Pentatomidae are usually barrel-shaped and are cemented in com- 
pact clusters on the surfaces of leaves or branches, many species having 
beautiful iridescent colors and bearing a fringe of processes around 
a dorsally located cap. Eggs of the Coreidae are generally cylindri- 
cal and cemented flat in loose clusters or rows on plant surfaces. ‘The 
Miridae, Anthocoridae, and Nabidae insert elongate cylindrical eggs 
into plant tissues. The eggs of the Tingidae appear as black, volcano- 
shaped structures on the under side of leaves, usually along the veins. 
One thing in common among eggs of most heteropterous Insects 1s the 
presence of a removable cap at one end, which has a diameter approxt- 
mately the same as that of the egg. 
