STUDIES ON PERILLUS BIOCULATUS FAB. 77 
is attained. The first two instars are very similar, the chief difference 
being in size. During the third instar a difference in the red coloration 
may be noted, for in some individuals the original tomato red color 
is retained while in others the color may become orange red. In the 
fourth instar the margins of the meso- and metathorax become sinu- 
ated; in the fifth instar distinct wing pads are developed. (Plate I.) 
First nymphal instar. Length 1.5 mm., greatest width 0.97 mm. ; 
black: abdomen tomato red, with five dark patches on median line, 
lateral margins of segments with heavily chitinized black spots which 
join with similar spots on the ventral surface. The line formed by 
posterior margin of metathorax practically transverse. Antennae four- 
segmented ; tarsi two-segmented. 
Second nymphal instar. Length 3 mm., greatest width 2.3 mm.; 
similar to the first stage except in size. 
Third nymphal instar. Length 5.2 mm., greatest width 4.3 mm.; 
very similar to the preceding stage but in some individuals the tomato 
red color may become orange red. The black color of the thorax may 
frequently show distinct greenish reflections; also the sclerites of the 
metathorax show a slight change in outline. (Plate I.) Tergites 
of the abdomen finely punctate. 
Fourth nymphal instar. Length 6.5 mm. to 7.5 mm., greatest width 
4.5 to 5 mm. Distinguished from the preceding instar by the sinuated 
outline of meso- and metathorax. The red coloration exhibits two 
distinct phases; the tomato red color may be replaced by reddish 
yellow but the dark markings remain much the same. The thorax is 
usually blackish with a greenish luster. Punctures on abdomen more 
distinct. 
Fifth nymphal instar. Length 8 to 9 mm., width 5.5 to 7mm. In this 
instar there are two distinct forms, the dark form in which the corium 
of the adult will be black, and the light form in which the embolium and 
inner half (or margin) of corium will be white or yellowish. 
Dark form: Black, shining, with greenish luster, lateral margins 
of prothorax and frequently the outer margins of wing pads at base, 
yellowish to red; abdomen orange to red as in the preceding instar 
but with the dark chitinized areas larger and more prominent. Punc- 
tures of abdomen becoming fuscous or black. Wing pads strongly 
developed, attaining hind margin of second abdominal tergite. 
Pale form: Head, antennae, and legs black to greenish, tibiae more 
or less pale on middle third; thorax and abdomen chiefly white or 
yellowish, abdomen with dark spots similar to the preceding stage 
but much reduced in size. Prothorax with a pair of black spots on 
