204 



TREES AS GOOD CITIZENS 



Cankerworm 



Habits This is the worm commonly 



and known as the "measuring 



Damage, worm" or "looper," because 

 of its curious way of looping its 

 body in crawling. An attack by this 

 species may result in the destruction of 

 the entire foliage of a tree. The species is 

 divided into spring and fall types; the 

 latter is the one which attacks shade trees. 

 The eggs of the fall moth, shaped like 

 flowerpots, are laid in regular rows, 

 usually in rings around twigs near the 

 end of a branch. The eggs hatch into 

 caterpillars when the leaves start to 

 expand in the spring. These cater- 

 pillars feed on the leaves, and in June spin 

 silken threads by which they descend to 

 the ground to bury themselves beneath 

 the surface. They emerge late in the fall. 

 The egg-layers have no wings and must 

 crawl up the trunk of a tree to deposit 

 their eggs. 



Remedies. If unchecked by their 

 natural enemies the can- 

 kerworms become a serious menace to 

 trees. The first step is to prevent the 

 wingless females from crawling up the 

 trunks in order to lay eggs. This may be 

 done by banding the trees with some 

 sticky substance or cotton batting. 

 (Page 192.) These bands should be placed 

 late in September and kept in position 

 until the end of May. Where banding 

 has not been done, or where it has not 

 proved effectual, a tree which shows 

 signs of being heavily infested should be 

 promptly sprayed with arsenate of lead. 

 Necessity for spraying is shown by the 

 appearance of perforations in the leaves 

 when they are opening in early spring. 



White-marked Tussock Moth 



Habits One of the worst insect ene- 



and mies to the Elm and other 



Damage, shade trees, sometimes destroy- 

 ing the foliage of the trees in 

 an entire community. City trees seem 

 especially susceptible to its attacks. 

 When a tree becomes infested the signs 

 are at once visible, in the form of conspic- 

 uous egg masses on the trunk or larger 

 limbs; these masses are present from the 

 time of the egg-laying in September, until 

 the following spring. They are shiny 

 white, frothy looking patches, with four or 

 five hundred eggs in a single cluster. 

 Hatching takes place in May, with a 

 second brood in August, and each cluster 

 may produce hundreds of caterpillars. 

 The caterpillars immediately attack the 

 leaves, first reducing them to transparent 

 skeletons and finally devouring all but the 

 principal veins. After five weeks the 

 caterpillars weave cocoons in which they 

 go through the stages of transformation, 

 emerging as moths to repeat the egg- 

 laying and hatching process for a second 

 time and in warm climates for a third time 

 during the same season. The full grown 



Remedies. Destruction of the egg 

 masses in the fall or winter 

 is the simplest and most effectual means 

 of control. They may be easily picked 

 off by hand, or scraped off and burned; or 

 they may be destroyed by spraying or 

 daubing with creosote oil, kept liquid by 

 being mixed with turpentine. It will be 

 found that because the masses are loosely 

 attached the removal can be accomplished 

 with little effort. If any of the eggs 

 remain and are hatched the tree must be 

 thoroughly sprayed with arsenate of lead, 

 completely covering all infested foliage. 

 The spraying should be done with equip- 

 ment and method similar to those out- 

 lined for the control of the fall webworm. 

 (Page 203). 



The tussock moth does not appear 

 every year, for the reason that it has a 

 number of natural enemies which keep 

 it in check. 



