214 NATURAL HISTORY OF ARTHROPODS. 



In the family COCCIDJE we reach the most anomalous forms to be met with in any 

 part of the great class Insecta. Indeed, in many cases these creatures can hardly be 

 said to have any particular form. The males are consistent in having one pair of 

 transparent wings, of a generally obovate form, provided with a stout vein, which 

 forks near the base and sends off one long branch near the costal border and another 

 towards the posterior edge. Instead of hind wings they have a pair of halteres or 

 balancers, each furnished with a hooked bristle, which fits into a pocket on the fore- 

 wing of the corresponding side. This sex also lacks the mouth-parts which it 

 possessed in its earlier stages ; and it undergoes the final metamorphosis from a quiet 

 pupal stage beneath the protecting scale. But the strange forms of the females have 

 been, by reason of their resemblance to parts of plants and trees, a soiirce of mistake 

 and confusion to observers everywhere. These females soon pass from the active 

 stage in which they began an independent existence, select a spot upon the twig or 

 leaf of the food-plant, insert the slender rostrum into the bark, contract the legs and 

 other appendages, and settle down for the remaining few months of their existence in 

 shapeless lumps of waxy matter, in gall-like spherical bodies, or in oval or oblong 

 flattened scales. In some of the species belonging to a division of this family, the 

 Coccina proper, this sex preserves throughout the activity and somewhat the form of 

 the larval stage. The above constitute the principal characters by which to separate 

 this family from its nearest relatives, but as its subdivisions are peculiar in habits and 

 metamorphosis, we must consider each separately. 



The first sub-family to be noticed is named Diaspina from its principal genus 

 Diaspis. It contains some of the most pernicious insects in existence, which, by 

 reason of their vast multiplicity, ruin or destroy whole orchards of valuable fruit 

 trees, or groves of shade trees. These are preeminently the scale lice. A familial- 

 example may be cited in the Oyster-shell bark louse of the apple, Mytilaspis pomorum. 

 As its name implies, it is of the shape of a narrow, curved mussel or oyster-shell, 

 about one-twelfth of an inch in length, bluntly rounded on the broad end, of a dull, 

 horn brown color, tinged with gray, with the projecting edges of the exaviffi more or 

 less yellow, and with the body yellowish-white. The scale of the male is smaller, 

 of the same general color, but straighter, and having the posterior division hinged to 

 the forward part by thinner integument. 



This species has been introduced into the United States from Europe, and has 

 been found more hurtful to apple-trees in the Northern and Middle States than in the 

 South. It is also said to be single-brooded in the former and double-brooded in the 

 latter. In the latitude of Maryland the eggs begin to hatch in April or May, accord- 

 ing to the forwardness of the season, and continue to do so until warm weather is 

 settled early in June. Countless multitudes of these dark scales, packed together as 

 close as they can lie, may be seen upon twigs and small branches of the trees in 

 neglected orchards. The bark is made rough by their thickly strewn bodies, and takes 

 on the appearance of wrinkles, where they are very numerous. The eggs, when 

 freshly-laid, are of a flesh tint, but become white after maturing, and the number 

 beneath the female scale varies from about twenty-five to three or four times that 

 number. When ready to hatch, the body of the young insect shows through the 

 skin of the egg, and gives it a yellowish tinge. 



It has not been my good fortune to breed the male, but Mr. Riley describes it as 

 " translucent carneous-gray, with bands of purple-gray on the back of each ring of 

 the abdomen, and with portions of the rnesothorax and metathorax of the same color, 



