INSECTS AFFECTING PARK AND WOODLAND TREES 243 



rains occurring- in early spring- just as the insects are beginning to de\elop 

 and before the foliage is abundant enough to afford adecpiate shelter. Such 

 inclement weather undoubtedly destroys large numbers of these delicate 

 insects, and severe continued rains later in the season may also be quite 

 injurious, not only by washing the insects from the leaves or removing pro- 

 tective coverings from them, but also because the damp weather favors the 

 development of bacterial or fungus diseases. 



There are also a number of insect enemies which are very effective in 

 controlling these forms. Among the most important and certainly the most 

 conspicuous are our well known latly beetles or ladybugs, which mav be 

 observed in practically every portion ot the countrv, and are usually found 

 in numbers wherever plant lice are abundant. These little insects comprise 

 an entire family of beetles, most of them feeding very largely on plant lice 

 of various species. Their general forn-i ixnd api)earance is so familiar that 

 no description is necessary in this connection. The llower or syrphid tlies 

 are also very efficient checks on the increase of plant lice, and a number of 

 species may be found about jjlants where aphids are numerous. The eggs 

 of these insects are whitish, o\al, very delicate affairs with the surface of 

 the shell marvellously chased. The maggots or young of these flies may 

 be easily recognized by their somewhat conical appearance and usually 

 bright colors. The slender, pointed head of the creature is extended to its 

 victim and the fluids rapidly drawn from one plant louse after another. 



The aphis lions, or young of the delicate green, golden eyed lace- 

 winged flies, are also well known enemies of plant lice and are frequently 

 met with on bushes where these pests are numerous. The exceedingly 

 voracious young have a somewhat oval, depressed body with a flattened 

 head. They may be at once distinguished by the enormous forward pro- 

 jecting mandibles with incurved points meeting at the tip. The little 

 creature approaches a plant louse, grasps it between its enormous mandibles 

 and draws the nourishment from its struggling victim. Certain small four 

 winged parasitic flies, known as Chalcids, are also exceedingly beneficial 

 species and are important factors in keeping these insects in check. I he 



