April. VJ2Z 



BETTER FRUIT 



Page Seven 



Cherry Fruit-Sawfly and Its Control 



Bij W. P. DuRuz 



Division uf Pomology, U iiiversity of Calijorfiici 



THE cherry fruit sawfly, Hoplo- 

 campa cookei (Clarke) does consid- 

 erable damage to cherries and plums 

 in certain fruit districts. The insect has 

 not spread rapidly, so control measures have 

 not been very urgent. Severe loss, however,, 

 has occurred at times to a few California 

 growers, and it is necessary to have a full 

 undertsanding of the insect and the latest 

 remedies thit will check any outbreak in 

 the future. 



F. B. McKevitt, Jr., of Vacaville, ex- 

 perienced great loss in his plums from the 

 cherry fruit sawfly in 1920, and it was at 

 his suggestion that a study of this insect 

 was undertaken, w'ith a view of working out 

 a satisfactory control. He generously vol- 

 unteered the use of his orchard and made 

 spr.aying treatments as suggested. This is a 

 report of the one season's work, which has 

 revealed the h.ibits of the insect and some 

 points, thought valuable in controling it.* 

 Nature of Injury — The larva of the 

 cherry fruit sawfly attacks the small fruits 

 of the cherry, (sweet and sour), plum and 

 prune, and, occasionally, apricots and 

 peaches. It also feeds on wild plums and 

 willows. Mr. McKevitt describes the in- 

 jury as follows: "The plums were ap- 

 parently all right until they were about 

 as large as peas, when they turned vellow 

 and dropped off." 



The presence of the larva is first ap- 

 parent from a dark decayed area on the very 

 small fruit (Fig. 1). On cutting open one 

 of these fruits, the small whitish slug-like 

 larva is revealed. It is from one-eighth 

 to one-fourth inch long, always rests in a 

 curved position and feeds on the kernel 

 and much of the fleshy portion of the 

 fruit. If the kernel is hard, onlv the 

 flesh is eaten. 



The injury is even more noticeable from 

 the clean round holes bored into the fruit 

 by the larva in entering and going out of 

 the fruit (Fig. I). One larva may injure 

 three to four fruits and cause a loss of from 

 tifty to ninety per cent of the crop. Mr. 

 McKevitt estini.ued his loss in 1920 at 

 $3,000 on Diamond and Grand Duke 

 pluins alone. 



Distribution — According to Professor 

 F.ssigf this insect is distributed through- 

 out Central California and as far north as 

 Southern Oregon, where it has been found 

 in the Rogue River Valley. The insect was 

 first found in Suisun Valley, by Matthew 

 Cookej; in 1883. The writer has found 

 this insect in plums and cherries in the 

 McKevitt orchard and at the Bucktown 

 ranch at Vacaville. 



T IFE History ov the .Adult — Foster§ 

 -L' states that the female sawfly ap- 

 pears in the spring alx>ut the time the 



early varieties of sweet cherries — Chapman, 

 Black Tartarian, etc.' — are beginning to 

 bloom. The adults are mostly black with 

 yellowish or reddish-brown appendages. 

 Thev are about one-eighth inch long, with 

 broad body and have two pairs of well 

 developed wings. They are usually quiet, 

 especially early in the morning, but as the 

 atmosphere becomes warmer toward noon, 

 they flutter about in the trees in search for 

 places to lay their eggs. 



The Egg — Egg laying (in the Suisun 

 Valley) begins about March 20. The eggs 

 are laid by the females in the sepals or 

 upper part of the caly.x cups of the expand- 

 ing blossoms. The sharp ovipositor or 

 "'saw" is used to make the incision in the 

 tissue and for placing the eggs. The eggs 



Above: Larvae of cherry-fruit sawfly feeding on 



cherry fruit. The kernel has been eaten. Below: 



Plums damaged by sawfly larvae. 



are usually deposited singly just before the 

 petals open. 



The Larva — The time of hatching of 

 the larva coincides closely with the falling 

 of the petals from the blossoms of the 

 \ariety attacked. Upon hatching it soon 

 finds it way to the bottom of the calyx cup 

 and cats directly into the newly formed 

 fruit and devours the kernel, which it 

 prefers. The fruit thus injured turns 

 yellow and withers. The larva then attacks 

 a second fruit, entering it any place on the 

 surface and, as in the first attack, eats out 

 the kernel if it has not hardened. 



The second fruit, being larger, usually 

 withstands the effects of feeding longer. 

 The growth, however, is checked and it 



gradually turns a pale green colot and 

 hangs on the tree (Fig. I) for some time. 

 .A third and sometimes a fourth fruit may 

 be attacked in this way. One larva usually 

 destroys three fruits while some attack four. 



When full grown the larva leaves the 

 fruit and makes it way to the ground, 

 where it pupates. 



The Pupa — Foster states the following, 

 relative to pupation; "The larva constructs 

 a small parchment-like cocoon which is 

 found three to seven inches below the sur- 

 face of the ground. The outer surface 

 of the cocoon is covered with fine particles 

 of soil, giving it the appearance of a small 

 clod of dirt. The larva remains as such 

 in the cocoon until the following w'inter. 

 Some time after the winter rains begin it 

 transforms to pupa and emerges the fol- 

 lowing March as an adult. The pupa has 

 not been observed. There is only one 

 brood each year." 



Control Experiments — P. J. O'Gara 

 ft of Medford, Oregon, had conducted 

 experiments for three years which led him 

 to state in 1913 that two to three applica- 

 tions of arsenate of lead would control this 

 insect. Mr. Foster recommended spraying 

 with a three per cent distillate-oil emul- 

 sion, to which had been added nicotine 

 sulfate at the rate of one part to 2000 

 parts of water, same to be applied in the 

 early mornings when the adults are on the 

 trees, but very sluggish. 



These are the only suggestions ever pub- 

 lished on control measures. 



A S HAS been stated, Mr. McKevitt of- 

 -^*- ferod the use of his plum orchard, 

 which was known to be infested with this 

 insect. The trees selected were about 25 

 years old and of the Diamond and Grand 

 Duke varieties. Nine blocks, of twenty 

 trees each, were selected, and each block 

 given a different spray treatment, (see 

 table). A power sprayer was used and the 

 spray applied with spray guns. 



Counts of infested and non infested 

 fruits were made throughout the different 

 blocks. Obviously, all the young fruits 

 on such a large number of trees could not 

 be counted in the time available, so careful 

 estimation was used to supplement the 

 actual counts. Casual observations of in- 

 terested persons coincided with the counts 

 iCi.ntiniied on page 24) 



"The writer is imUhtecI to Messrs. F. B. McKevitt. 



Jr., and George .Mlt-n for their hearty co-operation 



and assistance in conductinpr this investigation. 



'i'Essig. E. f).. Injurious and Beneficial Insects of 



California, Monthly Bulletin State Commission of 



Horticulture, X'olume I\'. No. 4, 191.'^. 



t Injurious Insects of Orchard and \'ineyard, pp. 



I.5/-138, 188.1. 



SBulletin 116, Part III, Bureau KntomoltiRy. Tie- 



nartment of .-XKricuIture, 1911. 



ttCalifornia State Commission of Horticulture, 



.Monthly Bulletin, Volume, III, No. 1, pp. ,11-35. 



