16 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 47 



Control Measure 1 or 2 (end of circular). Some people 

 grow catalpa trees mainly to raise caterpillars for fish bait, but 

 most tree lovers want to protect their trees from these cater- 

 pillars. 



Comstock Mealybug, Pseudococcus comstocki (Kuw.) . — An 

 occasional pest of catalpa, the Comstock mealybug is likely to be 

 found in cottony masses at the forks of tender shoots or at the 

 bases of leaves. The male, which has wings, is seldom seen. The 

 female, a wingless, slow-moving insect, when grown is about 

 one-fourth inch long and elliptical in shape; she has a fringe of 

 short, soft spines and is covered with "mealy," white wax. A 

 sucking insect like the aphid, the mealybug likewise secretes 

 honeydew, which supports a sooty mold. 



The mealybug's yellow eggs, found in crevices of bark, are 

 covered with a cottony mass of wax. When leaves appear on 

 catalpa trees in spring, the eggs hatch, and the young mealy- 

 bugs move to likely places to feed and grow. This insect may 

 produce several generations a year. 



Control Measure 3 (end of circular) applied with force. Two 

 or three spray treatments may be needed. 



CRABS AND HAWTHORNS 



Yellow-Necked Caterpillar, Datana ministra (Drury), fig. 

 10. — While seeming to prefer the foliage of apple and other fruit 

 trees, the larva of this species finds nothing distasteful about 

 the foliage of ornamental crabs and hawthorns wherever these 

 plants are grown. Reddish in color when young, the ugly, fuzzy 

 caterpillar has a yellow neck. It has a black head and four yel- 

 low stripes along each side of its body. Caterpillars of this spe- 

 cies feed ravenously in groups, but, when disturbed, they stop 

 feeding and rear up at both ends. When fully grown, each cat- 

 erpillar drops to the ground, burrows in a short way, and pu- 

 pates. The adults, or moths, appear in early summer, and at 

 about this time the female deposits eggs in clusters on the 

 under sides of leaves. 



Control Measure 1 or 2 (end of circular) when caterpillars 

 are small. 



Woolly Hawthorn Aphid, Eriosoma crataegi (Oest.), fig. 11. 

 — Occurring in dense colonies on twigs and branches, the white, 

 restless plant lice of this species are conspicuous. They may 



