INSECTS AFFECTING PARK AND WOODLAND TREES 1 5 



ova with cementlike secretions. Others, like the gipsy moth and the brown 

 tail moth, cover theirs with scales or hairs from the body, and still others 

 depend on a protective resemblance and either oviposit in conspicuous 

 places or lay them so tlatly, as in the case of the nearly transparent eggs of 

 some species of leaf rollers, that they escape all but the sharpest scrutiny, 

 even when on the exposed surface of a leaf. Those interested in ingenious 

 devices for concealing or protecting these delicate objects, or who are 

 attracted by beauty of form and sculpture, will find the study of insect eggs 

 a fascinating one. In certain cases the ova or eggs hatch within the body 

 of the parent, while from others young appear about nine months after 

 deposition. The larvae of a few species of insects are known to possess 

 the somewhat anomalous power of producing young under certain 

 conditions. 



No iiictamoi'p/iosis. Members of the very lowest or simplest order of 

 insects, the Thysanura, which includes forms such as snow fleas, slides or 

 silver fish and their allies undergo no transformation, i. e. there is very 

 little or no difference, except in size, between recently hatched young and 

 adults. 



Incomplete iiiefaniorp/iosis. Grasshoppers and other related insect? have 

 what is knowm as an incomplete metamorphosis or transformation, which 

 means that there is a gradual development through a succession of active 

 stages to the adult. The immature individuals are frequently spoken of as 

 nymphs, and our best authorities confine this term to the young of forms 

 having an incomplete metamorphosis. The young grasshopper, as it 

 emerges from the &'g%, is a curious wingless little creature, bearing a general 

 resemblance to the adult, and one which can easily be recognized as a grass- 

 hopper. The little fellow increases in size, and from time to time casts its 

 skin because the comparative inelasticity of the epidermis, or exoskeleton 

 permits of only a limited expansion. The wing pads become longer with 

 each molt, and in the final change the wing cases are slipped off and the 

 organs of flight are at liberty to perform their proper functions. The wing 

 pads may be nearly as long as the fully developed wings in the stage pre- 



