ECONOMIC ZOOLOGY — ENTOMOLOGY. 457 



1910. An examination of the orcliard from wliich tliis sawfly leaf miner had 

 been collected showed that more or less of the leaves on nearly all of the trees 

 of the English Morello cherry had shriveled and died, others with well-defined 

 light-colored areas or blisters revealing a loss of chlorophyll. 



In addition to the cherry the hawthorn serves as a host plant. Of the cher- 

 ries, it has so far largely confined its attacks to the English Morello variety. 

 In its attacks on hawthorns the leaf miner tunnels the foliage in the same 

 manner as in the cherry. The authors' observations indicate that the insect 

 is more destructive to certain species of Crataegus than to the cherry. As a 

 cherry pest the leaf miner is definitely known to occur in injurious numbers 

 in orchards of English Morello cherry about Geneva in western New York and 

 about Germantown in the Hudson Valley. A study of the literature has failed 

 to reveal any record of its occurrence as a cherry pest outside of New York 

 State. As a depredator of hawthorns it has a wider distribution, being known 

 as a serious pest about Boston, Mass., and as common on various species of 

 Cratfegus growing in the vicinity of New York City, Rochester, Ithaca, Geneva, 

 and Skaneateles. 



Technical descriptions are given of its life stages. The sawflies make their 

 appearance as the first leaf clusters are unfolding and the cluster buds are 

 beginning to open. Oviposition commences soon after emergence from the 

 ground, which in 1913 was first obsei'ved on May 6. In examinations for the 

 location of the point of deposition of the eggs, it was found that they are 

 more often deposited near the base of the leaf than the tip. From 1 to 5 eggs 

 were observed on a single leaf and the average for all observations was 2.3 

 eggs per leaf. In 1913 young larvae were first observed on May 24, as the 

 trees were coming into full bloom, and by May 27 the hatching period was 

 practically completed. Eggs deposited on cherry leaves in the insectary hatched 

 in 8 days. Upon hatching out the young larva works its way through the 

 tissue of the leaf until it reaches the upper epidermis, usually mining toward 

 the distal end of the leaf. Upon reaching maturity the larvre make a hole 

 in the tissues forming the mine and escape to the edge of the leaf, thence to 

 the ground. In 1912 the larvfe began to leave the foliage on June 7 and by 

 June 10 it was estimated that 50 per cent had abandoned their mines. 



The chalcidid egg parasite Trichogramnia minutum is said to be a common 

 enemy of this leaf miner, the parasitism in 1915 ranging from 40 to 90 per cent 

 on individual trees. An ichneumonid parasite reared from P. collaris is de- 

 scribed by Rohwer (see p. 456) as Pezoporus tentliredinarum. As regards 

 control measures it is thought that picking the affected leaves will prove most 

 effective and economical in controlling this insect. The removal and destruction 

 of all mined leaves, coupled with the practice of destroying wild hawthorns in 

 the immediate vicinity of a cherry orchard, should leave few opportunities for 

 the pest to develop to injurious numbers. Of the various measures employing 

 insecticides to protect cherry foliage from the work of the leaf miner, fumiga- 

 tion with hydrocyanic acid gas alone was effective. The authors state, how- 

 ever, that it should only be undertaken as an extreme measure and in an 

 experimental way under expert direction. It is pointed out that fall or early 

 spring plowing or cultivation may be of value in destroying the larvse in the 

 soil. In the protection of hawthorns in decorative plantings the practice of 

 spraying seems to be preferable, the most satisfactory results having been 

 obtained from the use of nicotin at the rate of 1 pint (40 per cent solution) to 

 100 gal. of water to which 4 lbs. of soap has been addded. This should be 

 used in liberal amounts and applied with rather high pressures at the time 

 when the insects first begin to mine the foliage. 



