LIBRARY

HEMIPTERA 333
Cornic1es or oil- or wax-secreting organs absent or present; variable in size
and shape from mere rings to long, cylindrical or swollen, straight or curved
tubular organs almost as long as the body; smooth, imbricated, partly reticulated,
or hairy, with or without flaring opening. Seven pairs of spiracles; with
cauda or tail, anal plate, genital plate, and rarely with precaudal tubercle (in
Cavariella). Male genital organs consist of a pair of valves, penis, and genital
plate.
The biologies of aphids present to the student some complex problems owing
to the number of kinds of forms, reproduction by parthenogenesis and sexuales,
alternation of host plants, and variations in the life histories because of climatic
factors.
Kinds of forms
1. Fundatrices or stem mothers - apterous or winged, viviparous,! parthenogenetic
2 females. From overwintering eggs on the primary
host.
2. Fundatrigenire - apterous or winged, viviparous, parthenogenetic fe·
males. Several generations from the fundatrices. This form may be
omitted in some species of the subtribes CALLIPTERINA and DRE­
PANOSIPHINA in which only certain of the sexual forms are truly
apterolls as in Callipterus, Myzocallis, Drepanaphis, Drepanosiphum.
and others.
3. Migrantes or migrants - winged, viviparous, parthenogenetic females
arising from the second or third generations of the apterous fundatrigenire
on the primary host. They disperse or migrate either to other
similar hosts, where they give birth to apterous and winged individuals,
or to secondary hosts, where they usually produce only apterous
forms.
4. Alienicolre or seconds - apterous, viviparous, parthenogenetic females
born on the secondary hosts and comprising several to many generations.
They appear much the same as the fundatrigenire.
5. Sexuparre or gynoparre - apterous or winged, viviparous, parthenogenetic
females, offspring of the alienicolre, which give birth to apterous or
winged sexuales, either on the secondary host or after migrating back
to the primary hosts.
6. Sexuales or sexes - male and female progeny of the sexuparre, either
born on the secondary host, whence they migrate to the primary
host, or born on the primary host. Females usually apterous; males
apterous or winged or both forms may occur within the species. They
feed very little or not at all, develop rapidly, and mate. The females
lay from one to several or many eggs, usually around the buds or On
1 These forms are also often referred to as being ovoviviparous because the egg hatches
within the body. .
• Reproducing without mating.