80 



In this condition they pass through the winter, and it is not until the following 

 spring that the sexes are developed. Some of the ecales will then be noticed to increase 

 in size, and these are the females. Under the smaller scales the transformations of the 

 males take place, and they are remarkably difierent from those of the females, for in this 

 sex there is what is not found in any other member of this order, a complete metamor- 

 phosis. These males remain under the scales (their outer skins) from which they detach 

 themselves, until they evolve as perfect insects. After the insects have paired, the body 

 of the female dries up, the whole substance apparently being consumed by the enormous 

 number of eggs she lays. Many of these insects are exceedingly injurious to vegetation, 

 and are difficult to combat. We have several species in Canada, but there is little positive 

 knowledge concerning them. It is a very curious thing how they migrate from one tree 

 to another. They will appear suddenly on trees which have been without them for years. 

 This year, and from the amount of downy material in which it envelops its eggs, a very 

 conspicuous species has appeared for the fii'st time on a Virginian creeper near my house. 

 There were, perhaps, a dozen females this year, and on examining the young shoots a 

 few days ago, I found them well stocked with the half-grown scales. This species seems 

 to answer the description of one Harris mentions on page 256, a thorough investigation 

 of which he was prevented from carrying out by its premature destruction by fire, together 

 with the grape-vine upon which it was feeding. 



The Aspidiotus conchiformis, oyster-shell bark louse, attacks many different trees, 

 but chiefly the apple. It has also been found on the currant, plum, pear, cherry, and 

 apricot. Fig. 9 1 represents a twig of an apple 

 tree covered with these scales. This is becom- 

 ing a very injurious pest in Ontario, and un- 

 luckily gardeners seem to have got an idea that 

 nothing can be done to stop its ravages, so let it 



take its chance. I have been frequently told " ~ -p. 



that it was useless to ftpply the soap wash, on 

 account of the insect being protected by a scale. This of course is not the case. If a 

 strong mixture of whale-oil soap, with tobacco in it, is syringed on the trees four times 

 through the month of June, it can be kept well in hand, because then the young larvae 

 are unprotected by a scale. 



Although the greater number of the Coccidse are so injurious, yet there are some 

 among them which produce commodities of very great commercial value. It is from the 

 female scales of C. lacca, a species of this family which attacks Fieus indica, that the 

 Indian product lac is obtained. This substance has many uses in the economic arts ; it 

 is the chief ingredient in sealing wax and several varnishes, and is also the basis of French 

 polish. In India it is mixed with sand to form grindstones; dissolved in water and mixed 

 with ivory black it makes a good ink. It is also from this insect that the colouring 

 matter called lac-lake is prepared, which has been used as a substitute for cochineal. 

 The East India Company are said to have saved in a few months $70,000 in the purchase 

 of scarlet cloth dyed with a mixture of this colour and cochineal conjointly, and this 

 without any inferiority in the colour obtained. These scales are known as stick-lac when 

 they are unseparated from the twigs upon which they formed ; seed-lac when removed 

 and pounded, and a part of their colouring matter extracted in water ; lump-lac when 

 melted down into cakes ; and shellac when strained and allowed to harden in thin laminae 

 or flakes. But the most valuable of these insects is, perhaps, the Cochineal (0. cacti), 

 which attacks a kind of indigenous cactus (Opuntia cochinillifera) found in Mexico where 

 it is called nopal, and which is cultivated in plantations called nopalleiros, for the express 

 purpose of feeding these insects. It is one of the most remunerative industries of the 

 country. It has been calculated that 70,000 dried insects are required to make a pound 

 of cochineal. In 1866 England imported 32,757cwt., valued at £594,818, and exported 

 21,238cwt, the annual consumption being about 12,000cwt. The price in 1870 was 

 about 3s. a pound. In 1871 the imports into the United States were 1,849,8421b, valued 

 at $1,184,255. Many attempts have been made to introduce this insect into other 

 countries. The East India Company even offered a reward of £6,000 to anyone who 

 would introduce it into India. It was introduced into the Canary Islands about 1830, 



