INSECT PESTS OF OHIO SHADE AND FOREST TREES 297 



maple scale. Another lady-beetle, Chilocorus hivulnerus Muls. is 

 reported as an enemy. As a usual thing, however, minute parasitic 

 wasps may be considered the most useful of our natural enemies 

 against this insect, the following having been reported : Cocopha- 

 gus lecanii Fitch, C. flavoscutellum Ashm., Atropates colli7isi How., 

 Aphycus pulvinariae How., Coniys fusca How. and Eunotus lividus 

 Ashm. In addition to the foregoing list may be named as enemies 

 of this .scale, a predaceous caterpillar, Laetilia coccidivora Comst., 

 a dipterous parasite, Leucopis nigricornis Egger and a bird, the 

 common English sparrow. 



Control. — Some value may be attached to the use of kerosene 

 and other oily emulsions applied in the summer when the young are 

 appearing, but at best this treatment is satisfactory in part only, 

 due to the mechanical difficulty attached to spraying thoroughly 

 when the host is in foliage. In the writer's experience far more 

 satisfactory results have been obtained by spraying with miscible 

 oil, 1 part to 15 parts of water, in the spring before the buds break. 

 This treatment destroys the over-wintering partially-mature 

 females attached to the twigs and smaller limbs. A word of 

 caution, however, should be expressed, that quantities of the oily 

 spray should not be permitted to soak into the soil at the base of 

 the tree since maples are sensitive to the action of oils. 



COTTONY MAPLE-LEAF SCALE 



{Pulvinaria acericola Walsh and Riley) 



Description. — This scale insect closely resembles the foregoing 

 species in general appearance. However, aside from the minute 

 microscopial differences, it may be differentiated easily because the 

 body of acericola is dotted with blotches of white cottony wax while 

 the body of vitis is bare. Moreover, aericola usually occurs during 

 the adult stage on the leaves of the host, while vitis is found upon 

 the twigs and branches. (See Plate LII, Fig. 3.) 



Life history and habits. — Both males and females of the cot- 

 tony maple-leaf scale pass the winter in a partially matured con- 

 dition upon the twigs of the host. By late April or early May 

 of the following spring, the males mature and after fertilizing the 

 females, the latter migrate to the leaves where they reach maturity, 

 secrete their white cottony ovisac and deposit their eggs. The fol- 

 lowing June the larvae begin to hatch. They feed for a time upon 

 the leaves and later migrate to twigs and branches for the winter. 

 There is but one brood per season. 



Nature of work. — The injury caused by the cottony maple-leaf 

 scale is not so severe as that caused by the maple cottony scale. 



