78 MICHIGAN ACADEMY OF SCIENCE. 



tuberculosis which is a true parasite; and the disease is spread (directly 

 and indirectly) only from infected animals and persons. 



7. Tuberculosis in cows is easily restricted. 



S. As a nu^asure of i)ecuniarv economy to citizens of the State, and 

 also in the interest of the public health, it is the imperative duty of 

 the State to promptly take such action that tuberculosis in cows shall 

 be restricted; and that the ])resent very considci-able and unnecessary 

 waste of human life because of infected milk shall be stopped. 



THE SCALE-INSECTS OR COCCID.E. 



U. 11. PETTIT, AGRICULTURAL COLLEGE. 



The family of scale-insects or Coccidie forms a natural group, well 

 defined and quite distinct, in many ways, from the rest of the hemiptera 

 with which it belongs. It comprises about 800 species at the present 

 time and new species are constantly being added as they are discovered. 



As is usually the case where a natural group is well defined and quite 

 distinct from its allies, the members of the group itself are very much 

 alike and the distinctions between genera and species are very close. 

 When such a state occui's in a family of insects, whose members average 

 in size less than the head of a pin, there is ottered opportunity for 

 considerable study. 



The family Coccidte is placed in the Hemiptera Homoptera, usually 

 with the Alcurodida^ and PsyllidiP near the A])hida\ The fact that three 

 of these families have a common character, tliat of the beak apparently 

 arising from the sternum, has induced some authors to group the 

 CoccidiP, Aleurodidai' and PsyllidtF together into the super-family 

 Sternorhynchia. 



The members of the Coccidie have a life history that is unique. The 

 metamorphosis is incomplete with the females, and complete with the 

 males, a state of things that does not exist in any other group of 

 insects. The males all have a quiescent juijial stage and emerge as 

 very small, delicate two-winged creatures, whose lives are of such short 

 duration that they require no food and for this reason they have no 

 mouth-parts. In the })lace where the mouth ordinarily is found, there 

 is placed an extra pair of eyes. The second ])air of wings is re^luced to 

 a rudimentary condition and each is armed with one or more hooks at 

 the apical end which hooks are i)laced, during flight, in corresponding 

 folds in the front-wings. 



The female does not ])ass through such a nu4auu)ri)hosis. She is, as 

 an adult, always without wings, and has always a long beak to suck 

 food. The members of some genera are footless sacs, without antenniP 

 or eyes, and capable only of feeding and reproducing. Other genera 

 have females jiossessing freedom in difi'(M'ent degrees. The membei-s of 

 some genera have legs, antenna' and eyes during their entire life. Some 

 are enclosed in sacs of felted material, some secrete a covering of w'ax, 



