1J)U 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Food Plants. 1 '" : — Alder, almond, American aspen, false indigo 

 Amorpha), apple, crab apple, apricot, arrow-wood, ash, balm of 

 Gilead, basswood, beech, bilberry, white birch, river birch, bittersweet, 

 blackthorn, bladder nnt, boxwood, box-elder, broom, buckeye, buck- 

 thorn, butternut, camellia, camphor, cherry, chestnut, Clematis panicu- 

 lata, coconut, cotoneaster, cranberry, black currant, red currant, dog- 

 wood, elm, water elm, false bittersweet, fig, filbert, fir (Abies firma), 

 ginseng, gooseberry, goat's-beard, grape, hackberry, hawthorn, heath, 

 heather, holly, honeysuckle, hop-tree, horse-chestnut, Horena dulcis, 

 June-berry, leather leaf, leather-wood, lilac, lime, linden, locust, water 

 locust, maple, mespil, American mountain ash, European mountain ash, 

 mountain holly, myrtle, nectarine, New Jersey tea, oak, orchid, Pachy- 

 sandra terminates, peach, pear, peony, pepper grass, plum, poplar, 

 quince, raspberry, rock-rose, rose, sassafras, senna, silver thorn, Spircea, 

 sycamore, tallow tree, tamarisk, tree of Heaven, tulip-tree. Magnolia 

 tripitala, Viburnum, Virginia creeper, willow, English walnut and 

 yucca are among the plants attacked. 



Control.— As this species usually occurs on deciduous trees, spraying 

 with lime-sulphur (1 to 11) just before the buds open in the spring 



has given very good results. A 

 kerosene or crude oil emulsion ap- 

 plied in the winter is also effec- 

 tive. Commercial control is 

 seldom necessary in this State. 



Natural Enemies.— The follow- 

 ing internal hymenopterous para- 

 sites have been reared from the 

 oyster-shell scale: 107 the golden 

 c h a 1 c i d (Aphelinns diaspidis 

 How.), A. fuscipennis How., A. 

 mylitaspidis LeB., A. abnormis 

 How., Aspidiotiphagus citrinus 

 Craw, Anaphes gracilis How. and 

 ( 'h e ilo x e u rus diaspidin arum How. 

 Ladybird beetles also prey upon 

 it to a large extent. 



THE THREAD SCALE 



Ischnaspis longirostris (Signoret) 



(Mijtilaspis longirostris Signoret) 



(Ischnaspis filiformis Douglas) 



(Fig. 166) 



Description.— The common 

 name well characterizes this 

 scale, which is exceedingly long 

 and slender. The scales of the 

 adults are black, straight or 

 curved and from ,V to £ inch long. Fig. 166 shows them very well. 



Fig. 166. — The thread scale, Ischnaspis 

 longirostris (Sign.). Natural size. On 

 palm. (Original) 



■^Cir. No. 121. Bur. Ent. TJ. S. Dept. Agric, pp. 5-6, 1910. 

 '"Yearbook, U. S. Dept. Agric, p. 254, 1894. 

 Cir. No. 121, Bur. Ent. U. S. Dept. Agric, p. 6, 1910. 



