KATYDIDS INJURIOUS TO ORANGES IN CALIFORNIA. 19 
DURATION OF INSTARS. 
The average duration of the nymphal instars of the angular-winged 
katydid, as determined from a number of individual rearings, was as 
follows: Instar I, 13.8 days; instar II, 8.6 days; instar III, 9.5 days; 
instar IV, 10.2 days; instar V, 13.7 days; instar VI, 17.2 days. The 
average duration of the complete nymphal stage is therefore 73 days, 
or about 2i months. Molting is accomplished in about the same 
manner as by the fork-tailed katydid (see pp. 10-11. The nymph 
always eats the greater part of its cast skin after each molt, rejecting 
only the mandibles, claws, and certain hard parts of the head cast. 
The Adult. 
general appearance. 
The body of the adult is broad and compact, and comparatively 
very wide dorsoventrally (PL IV, fig. 2). The humpbacked appear- 
ance so characteristic of the later stages of the nymph is retained, but 
to a lesser degree, owing to the broadly rounded angle of the fore- 
wings. The hind wings extend the full length of the body beyond 
the tip of the abdomen. The color is uniform grass-green over most 
of the body, becoming yellowish green on the ventral surface. The 
insect is fully 2 inches long, the wings measuring, when spread as for 
flight, about 3 J inches. 
MATING. 
Mating rarely or never occurs earlier than 18 days after emergence, 
and the period between emergence and the first union of the sexes 
ranges from 18 to 26 days. Coitus is succeeded by the extrusion of 
a small, bilobed mass of albuminous material, which, as in Scudderia 
furcata, may be seen clinging to the abdomen at the base of the 
ovipositor in the female for several hours subsequent thereto. The 
favorite time for mating is at night, when the males are very active 
and may often be heard sending forth a loud and sustained clatter 
for several hours at a time. The stridulating note, once heard, is 
readily recognized, and to trace it to its source will often disclose both 
male and female katydids, as stridulation appears to be closely con- 
nected with courtship. The stridulating song of an allied species, 
Microcentrum retinerve Burm., has been described by Riley as con- 
sisting of " a series of from 25 to 30 raspings, as of a stiff quill drawn 
across a file" at the rate of "about five of these raspings or trills per 
second, all alike, and with equal intervals, * * * the whole 
strongly recalling the slow turning of a child's rattle." This descrip- 
tion is equally applicable to M. rhombi folium. 
OVIPOSITION AND LENGTH OF ADULT LIFE. 
In captivity females have deposited from 3 to 123 eggs each during 
