TRUE ORTHOPTERA 



3165 



SPRUCE-GAI.I, APHID (Chetmes abietis). 



Larva; b. An older larva with its molded skin still 

 attached to it; c. Winged insect; d. The gall. 

 (All enlarged.) 



the antennae are short, and in the tarsi, which appear at first sight to consist of 

 but one joint, two or three joints may on close examination be distinguished, 

 the last ending, as a rule, in a single claw. In many species the female dies shortly 

 after laying eggs beneath her when her body dries up and remains as a protec- 

 tive cover for them. When the larvae 

 are hatched they soon leave this shelter, 

 and rove about the food plant in search 

 of a suitable place in which to insert 

 their beaks and begin the operation 

 of pumping up the sap. They cast 

 their skin several times in the course of 

 their growth; and those which become 

 adult females undergo no great change 

 in appearance, beyond an increase in 

 their size, a gradual lengthening of the 

 antennas, and a partial or almost com- 

 plete obliteration of the segmentation 

 of their bodies. With the male larvae 

 the case is different; these, unlike all 

 others belonging to the order, undergoing a true metamorphosis before reaching 

 the perfect state. Each prepares for itself a sort of cocoon, and it becomes trans- 

 formed into a quiescent pupa, from which, after a certain lapse of time, the 



winged insect emerges. In Orthezia and other 

 genera the female, instead of keeping to one spot 

 on the food plant, moves about and taps it at 

 different points in order to extract the sap. 

 When the eggs are laid, she envelops them in 

 a kind of white cottony secretion and leaves 

 them. Some species penetrate beneath the 

 epidermis of their food plant, and often cause 

 the formation of galls, which, growing up around 

 them, sometimes take the most extraordinary 

 shapes. Scale insects are probably more numer- 

 ous within the tropics than in more temperate 

 regions, although comparatively few of these 

 tropical species have been described. These in- 

 sects are found on the bark and leaves, and some- 

 times even on the roots of several different kinds 

 of plants. They multiply rapidly, and often 

 prove as injurious as the most noxious plant 

 lice. The orange, apricot, olive, peach, fig, and 



other fruit trees, as well as ornamental shrubs like the rose, have each their 

 own species, from which they sometimes suffer severely. Some years ago the 

 orange plantations of California were threatened with ruin owing to the ravages 

 of Icerya purchasi, which had been accidentally imported' from Australia, and 



=^ --^ *; c '^^^^jf = ^^~ - V-.<T^J 



FEMALE OF Orthezia urticce. 

 (Natural size.) 



