"546 SIDNEY I. KORNHAUSER 
predacious dipterans often pounce down and carry the Thelia 
away without much trouble. 
In my principal collecting fields, Formica truncicola Nyl. 
subsp. obscuriventris and Cremastogaster lineolata Say were 
the chief ants associated with Thelia. When tapped by the 
antennae of the ants, the Thelia nymph or adult exudes from 
the anal tube a drop of clear fluid which is taken by the ant with 
great alacrity. Toward the middle of June, the ants build 
collars about the bases of the locust trees, and inside these collars 
in the cracks of the bark are to be found hundreds of Thelia 
nymphs of third to fifth instar, quietly feeding and undisturbed 
by the numerous ants in attendance. In this moist situation, 
protected from many of their enemies, the nymphs thrive. 
Formica builds the protecting collar of leaves, twigs, and bits 
of wood; Cremastogaster builds of sand grains cemented to- 
gether. When one breaks the collar, many ants swarm out and 
attack the intruder, Formica biting one’s fingers ferociously, 
while others grab the Thelias and drag them into underground 
passages. These pugnacious ants seem to have complete mas- 
tery of the Thelia nymphs. 
After completing its growth in the fifth instar, the Thelia 
emerges from the collar of leaves or sand, climbs higher on the 
trunk or branches of the tree, and molts into an adult. Mature 
males are first to appear, generally being found early in July. 
The females and parasitized adults of both sexes mature a week 
or two later. In July and early August, the adults sit motion- 
less on the bark and are not found in groups. One can often 
catch them. between the forefinger and thumb. The males, 
however, are more active than the females and hop or fly at less 
provocation. Both sexes are more active on hot, sunny days. 
Toward the end of August and in September, the individuals 
gather into groups on the branches or the trunk of the tree, and 
there is evidence of courtship, for very often one sees a single 
female surrounded by several males. In September, individuals 
mating can occasionally be found. The male and female face 
in opposite directions and the tip of the abdomen of the male is 
placed beneath the ninth abdominal segment of the female. 
