gO NINETEENTH REPORT STATE ENTOMOLOGIST OF MINNESOTA—IQ22 
Palmer (1922) also calls attention to the work of Physalix (1894) 
who made chemical tests of the red pigment in one of the Heteroptera: 
“Red coloration in the integument among some species of bugs 1s un- 
questionably carotinoid at times, perhaps carotin itself. Thus, Phy- 
salix (1894) extracted the red pigment [undoubtedly frem the hypo- 
dermal layer} of the hemipter, Phyrrhocoris apterus, from two liters 
of the insects. The pigment was deep red in carbon disulfide, yellow 
in alcohol and ether, gave the lipochrome reaction with concentrated 
H,SO,, and showed the absorption spectra of carotin. Physalix as- 
serted that the pigment was carotin or a very closely related substance.” 
In the case of Perillus, it is interesting to note that once the red 
pigment is laid down in the hypodermis of the adult, it is never 
diminished, thus it must be protected from oxidation. The case is 
different in growing nymphs, for the yellow and red nymphs may at 
times (under high temperatures) become distinctly paler even between 
molts, altho the most rapid changes occur at the time of molting. 
Adults and nymphs placed in alcohol (70 to 95 per cent) remain for 
years (10 years) without losing their characteristic red and yellow 
colors, while dried specimens preserved on pins and kept for the same 
period retain the bright red and yellow colors nearly as in life. 
The type of coloration manifested in Perillus bioculatus is exhibited 
in some degree throughout the order Hemiptera. In numerous forms 
examined, the yellow and red colors are all located in the hypodermis. 
Correlating the prevailing temperatures with extensive collecting of 
Neoborus amoenus (Reuter) and Horcias dislocatus (Say), indicates 
that the color varieties of these species are influenced by temperature 
in a manner similar to Perillus. 
In the present work no attempt has been made to determine the 
chemical nature of the pigments involved, but rather to arrive at some 
understanding of the ecological factors which influence or govern the 
production of color in the body wall of Hemiptera. To the biologist it 
is worth something to know when and how the color pattern manifests 
itself. It is left to the chemist to say what it is. 
In 1923 the writer interested Dr. L. S. Palmer, chemist and 
an authority on carotinoid pigments, in making chemical tests on the 
nature of the red and yellow pigment found in the hypodermis of 
Perillus bioculatus. Results of these experiments will be published 
elsewhere, but it may not be out of place to state that all the tests 
show the pigment to be nothing but carotin, the yellow or red color 
depending on the concentration of this pigment. Furthermore, chemical 
