Polyphagous Pseudo-californian Scale Insect

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

The Californian scale insect damages not only all berry and fruit crops, but also many decorative and forest species. And it lives almost everywhere, often forming numerous colonies, which completely cover the bark of branches and trunks from the lower sides. Despite the fact that only one generation of these parasites develops throughout the year, this is quite enough to say goodbye to a significant part of the long-awaited harvest. As a result of the suction of juices, the branches of trees are strongly bent, the growth of tissues is noticeably disturbed, a general weakening of fruit crops is observed, and the volume of the harvest and its quality also decrease

Meet the pest

The short-oval body of females of the pseudo-Californian scabbard reaches a length of one and a half millimeters and is colored in yellow-green tones. Moreover, the size of their grayish-brownish rounded scutes ranges from 2 to 2.3 mm. And the shields of male nymphs, also painted in grayish-brownish tones, are characterized by a short oval shape and reach a length of only 1 mm. Males of the Californian scale insect are yellow-orange and winged.

Larvae of the second instar, and a little less often females, overwinter on the bark of branches and trunks under the shields. The development of harmful larvae continues in April, and already at the beginning of May they molt and transform into males. The development of females usually takes from thirty to forty-five days. During this period, they increase in size, and with the onset of June and early July, they begin to lay eggs. For fifteen to twenty-five days, each female manages to lay from twenty-five to eighty eggs.

The duration of the embryonic period in pseudo-Californian scale insects is relatively short and ranges from several minutes or hours to a day. The revived harmful larvae instantly crawl over the trees, stick to their bark and almost immediately begin to form shields. Towards the end of June or in July, after shedding, they reach the second century of their development and fall into diapause until the spring of the next year.

How to fight

When planting fruit crops, seedlings free from pseudo-Californian scale insects should be used, since most often the spread of these pests occurs with grafting and planting material.

Skeletal branches and tree trunks must be cleaned of dead bark, and drying branches must be promptly removed. If individual trees have been inhabited with pseudo-Californian scale insects for quite a long time, then they are uprooted, taken out of the gardens and burned.

If for each square meter of branches there are more than two hundred larvae of the Californian scale insect, in the early spring period, trees are sprayed with ovicides on dormant buds. And at the stage of larval migration, insecticide treatment will also be expedient. In this case, only those areas where these polyphagous parasites were found should be treated with insecticides, since they are characterized by the focal nature of the settlement. Preparations based on mineral oils have proven themselves quite well in the fight against pests. Treatments with all of the above means must be carried out at an increased expense of funds, up to washing the boles and skeletal branches, since they are often covered with shields of gluttonous parasites.

If necessary, repeat treatments with insecticides are carried out. Usually, such treatments coincide with the time of the larvae dispersal. By the way, processing data can be combined with treatments against various diseases and any other pests.

The Californian scale insect has quite a few natural enemies. It is often infected by horsemen belonging to the chalcid family, and the larvae are eagerly eaten by spiders, ticks and many other predatory insects.